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EverydayCalc guides

EverydayCalc guides explain the assumptions, formulas, examples, and planning rules behind our calculators. Use these guides when you want to understand the numbers before making a purchase, planning a project, comparing options, or sharing an estimate.

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These broad guides are good first stops for common home, cost, moving, aquarium, finance, and classroom planning questions.

Home Air How to Choose a Dehumidifier Size Learn how room size, dampness, ceiling height, and cool basement conditions affect dehumidifier sizing. Costs Complete Electricity Cost Calculator Guide A complete guide to estimating electricity cost from watts, kWh, hours, rates, and monthly usage. Home Projects Complete Paint Coverage Guide A complete guide to estimating paint gallons, wall area, coats, coverage, waste, and beginner painting supplies. Moving Complete Moving Box and Supplies Guide A complete guide to moving boxes, truck size, storage units, tape, supplies, and moving cost planning. Finance How the Mortgage Payment Works Learn how the mortgage payment calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Aquarium Complete Aquarium Heater Sizing Guide A complete guide to aquarium heater wattage, tank gallons, temperature rise, placement, and safety checks. Education How the PBIS Reward Budget Works Learn how the pbis reward budget calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Moving How the Moving Cost Works Learn how the moving cost calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate.

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Moving Guides

Plan boxes, truck size, supplies, storage, and move-cost assumptions before packing starts.

Most useful

Moving How Many Moving Boxes Do You Need? Estimate moving boxes by bedrooms, occupants, storage, and packing style before ordering supplies. Moving How Many Moving Boxes for a 2 Bedroom Apartment? Estimate boxes for a 2 bedroom apartment by occupants, closets, kitchen items, books, storage, and packing style. Moving What Size Moving Truck for a 2 Bedroom Apartment? Choose a moving truck size for a 2 bedroom apartment by furniture volume, stairs, packing density, and trip distance. Moving Cross-Country Moving Cost Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the cross-country moving cost calculator. Moving How the Cross-Country Moving Cost Works Learn how the cross-country moving cost calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Moving First Apartment Moving Supplies Checklist Plan boxes, tape, packing paper, labels, cleaning supplies, and open-first essentials for a first apartment move. Moving How Many Boxes for a One Bedroom Apartment? Estimate moving boxes for a one bedroom apartment based on occupants, closets, books, kitchen items, and packing style. Moving How Many Boxes for a Three Bedroom House? Estimate moving boxes for a three bedroom house with closets, garage storage, kitchen items, books, and fragile packing.

More guides

Boxes and packing

Moving Box Chart and Examples How the Moving Box Works Moving Supplies Cost Chart and Examples How the Moving Supplies Cost Works Packing Paper Chart and Examples How the Packing Paper Works Packing Tape Chart and Examples How the Packing Tape Works

Trucks and containers

Moving Container Size Chart and Examples How the Moving Container Size Works Moving Truck Gas Cost Chart and Examples How the Moving Truck Gas Cost Works Moving Truck Size Chart and Examples How the Moving Truck Size Works Renting a Moving Truck vs Hiring Movers Chart and Examples How the Renting a Moving Truck vs Hiring Movers Works

Storage

Storage Unit Cost Chart and Examples How the Storage Unit Cost Works Storage Unit Duration Cost Chart and Examples How the Storage Unit Duration Cost Works Storage Unit Size Chart and Examples How Storage Unit Size Calculators Work

Labor, insurance, and supplies

Moving Insurance Chart and Examples How the Moving Insurance Works Moving Labor Cost Chart and Examples How the Moving Labor Cost Works

Other guides

Moving Cost Chart and Examples Moving Label Planner Chart and Examples How the Moving Label Planner Works

Home Air Guides

Understand humidity, dampness, room size, air purifier CADR, ventilation, and equipment sizing assumptions.

Most useful

Home Air Complete Home Humidity Guide A complete guide to indoor humidity, dehumidifier sizing, humidifier sizing, basement moisture, and comfort ranges. Home Air What Size Dehumidifier Do I Need? Choose a dehumidifier pint size by room area, dampness, humidity level, and basement conditions. Home Air What Size Dehumidifier for 1,000 Sq Ft? Estimate dehumidifier pint size for a 1,000 square foot basement, open room, or large area. Home Air Best Humidity Level for a House Understand comfortable indoor humidity ranges and when a house may feel too dry, humid, or musty. Home Air CADR vs Room Size: How to Size an Air Purifier Understand CADR, room volume, and air changes per hour before choosing an air purifier, including when to round up for quieter filtration. Home Air What CADR Air Purifier for a 300 Sq Ft Room? Estimate CADR for a 300 square foot room using ceiling height, air changes per hour, allergies, pets, and noise needs. Home Air 30-Pint vs. 50-Pint Dehumidifier Compare 30-pint and 50-pint dehumidifiers for bedrooms, basements, laundry rooms, and damp spaces. Home Air Air Changes Per Hour Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the air changes per hour calculator.

More guides

Dehumidifiers & humidity

Basement Dehumidifier Drainage Checklist Basement Dehumidifier Size Chart and Examples How the Basement Dehumidifier Size Works Basement Humidity Chart and Examples How the Basement Humidity Works Best Dehumidifiers for Basements Best Dehumidifiers for Bedrooms Crawl Space Dehumidifier Size Chart and Examples How the Crawl Space Dehumidifier Size Works Dehumidifier Electricity Cost Chart and Examples How the Dehumidifier Electricity Cost Works Dehumidifier Pint Size by Room Type What Size Dehumidifier for a 1,000 Sq Ft Basement?What Size Dehumidifier for 1,500 Sq Ft?What Size Dehumidifier for 300 Sq Ft?What Size Dehumidifier for 500 Sq Ft?What Size Dehumidifier for 800 Sq Ft?Dehumidifier Size Chart and Examples How the Dehumidifier Size Works Dehumidifier vs Air Conditioner Cost Chart and Examples How the Dehumidifier vs Air Conditioner Cost Works Humidifier vs. Dehumidifier Humidity Comfort Chart and Examples How the Humidity Comfort Works Humidity Level Chart and Examples How the Humidity Level Works What Size Dehumidifier for 1000 Sq Ft Basement?What Size Dehumidifier for 500 Sq Ft Basement?Whole-House Dehumidifier Cost Chart and Examples How the Whole-House Dehumidifier Cost Works

Air purifiers & filters

Air Purifier Annual Ownership Cost Chart and Examples How the Air Purifier Annual Ownership Cost Works Air Purifier CADR vs. Room Size Air Purifier Filter Cost Comparison Guide Air Purifier Filter Replacement Cost Chart and Examples How the Air Purifier Filter Replacement Cost Works What Size Air Purifier for a Bedroom?Air Purifier Size Chart and Examples How the Air Purifier Size Works Air Purifier vs HVAC Filter Cost Chart and Examples How the Air Purifier vs HVAC Filter Cost Works Best Air Purifiers for Bedrooms Best Air Purifiers for Small Rooms MERV Filter Size/Replacement Cost Chart and Examples How the MERV Filter Size/Replacement Cost Works

Heating & cooling

BTU Air Conditioner Room Size Chart and Examples How the BTU Air Conditioner Room Size Works CFM to ACH Chart and Examples How the CFM to ACH Works Heat Pump Savings Chart and Examples How the Heat Pump Savings Works Heat Pump vs Furnace Cost Chart and Examples How the Heat Pump vs Furnace Cost Works Heater Size Chart and Examples How the Heater Size Works Window AC Electricity Cost Chart and Examples How the Window AC Electricity Cost Works Window AC Size Chart and Examples How the Window AC Size Works

Fans, ventilation, and room sizing

Bathroom Exhaust Fan CFM Chart and Examples How the Bathroom Exhaust Fan CFM Works Bathroom Exhaust Fan Runtime Cost Chart and Examples How the Bathroom Exhaust Fan Runtime Cost Works Ceiling Fan Size Chart and Examples How the Ceiling Fan Size Works

Other guides

How the Air Changes Per Hour Works Humidifier Size Chart and Examples How the Humidifier Size Works Mini Split Size Chart and Examples How the Mini Split Size Works

Electricity Cost Guides

Compare appliance watts, usage hours, rates, monthly totals, state averages, and common cost mistakes.

Most useful

Costs How to Estimate Electricity Cost for an Appliance Use watts, hours, and your kWh rate to estimate daily, monthly, and yearly appliance electricity costs. Costs Average Electricity Cost by State Learn how average electricity cost varies by state and why your all-in kWh rate may differ from published averages. Costs Electricity Cost Calculator by State Use state electricity averages as a starting point, then estimate monthly cost with your actual watts and hours. Costs How Much Does It Cost to Run a Space Heater? Estimate space heater electricity cost from wattage, hours used, days used, and kWh rate, with notes on runtime, safety, and heating one room. Costs How Much Does It Cost to Run a 1500W Space Heater for 8 Hours? Estimate the daily and monthly cost of running a 1,500 watt space heater for 8 hours at common electricity rates. Costs How Much Does a Window AC Cost per Month? Estimate monthly window AC cost from watts, runtime, duty cycle, electricity rate, room size, and seasonal use. Costs How Much Does It Cost to Run an AC in Indiana? Estimate Indiana air conditioner cost using wattage, hours, season length, and your local electricity rate. Costs Appliance Replacement Savings Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the appliance replacement savings calculator.

More guides

Appliance costs

How the Appliance Replacement Savings Works Appliance Wattage Cost Chart and Examples How the Appliance Wattage Cost Works Ceiling Fan Electricity Cost Chart and Examples How the Ceiling Fan Electricity Cost Works Christmas Lights Electricity Cost Chart and Examples How the Christmas Lights Electricity Cost Works Cost to Run a 1500 Watt Space Heater Electricity Cost Chart and Examples How the Electricity Cost Works Gaming PC Electricity Cost Chart and Examples How the Gaming PC Electricity Cost Works Heat Lamp Electricity Cost Chart and Examples How the Heat Lamp Electricity Cost Works Home Office Electricity Cost Chart and Examples How the Home Office Electricity Cost Works Hot Tub Electricity Cost Chart and Examples How the Hot Tub Electricity Cost Works How Many Watts Does a Gaming PC Use?Laundry Cost Chart and Examples How the Laundry Cost Works Oven vs Air Fryer Electricity Cost Chart and Examples How the Oven vs Air Fryer Electricity Cost Works Pool Pump Electricity Cost Chart and Examples How the Pool Pump Electricity Cost Works Portable AC Electricity Cost Chart and Examples How the Portable AC Electricity Cost Works Refrigerator Electricity Cost Chart and Examples How the Refrigerator Electricity Cost Works

Heating and cooling costs

Best Space Heaters for Bedrooms Cost to Run a Window AC Pool Heater Cost Chart and Examples How the Pool Heater Cost Works Space Heater Electricity Cost Chart and Examples How the Space Heater Electricity Cost Works How Much Does It Cost to Run a Space Heater in Indiana?Space Heater vs. Central Heat Cost Space Heater vs Central Heat Cost Chart and Examples How the Space Heater vs Central Heat Cost Works

Fuel, generator, and backup power

Battery Backup Runtime Chart and Examples How the Battery Backup Runtime Works EV Charging Cost Chart and Examples How the EV Charging Cost Works Generator Fuel Cost Chart and Examples How the Generator Fuel Cost Works Generator Fuel Cost Comparison Chart and Examples How the Generator Fuel Cost Comparison Works Generator Size Chart and Examples How the Generator Size Works Portable Power Station Runtime Chart and Examples How the Portable Power Station Runtime Works

Subscriptions, internet, and everyday bills

Commute Cost Chart and Examples How the Commute Cost Works Gas Cost Chart and Examples How the Gas Cost Works Internet Cost Comparison Chart and Examples How the Internet Cost Comparison Works Monthly Subscription Cost Chart and Examples How the Monthly Subscription Cost Works Streaming Service Yearly Cost Chart and Examples How the Streaming Service Yearly Cost Works Water Bill Cost Chart and Examples How the Water Bill Cost Works

Solar and savings

Solar Panel Savings Chart and Examples How the Solar Panel Savings Works Solar Payback Chart and Examples How the Solar Payback Works

Other guides

How Much Does It Cost to Run a Dehumidifier?Dishwasher Electricity and Water Cost Chart and Examples How the Dishwasher Electricity and Water Cost Works Electric Bill Estimator by State Chart and Examples How the Electric Bill Estimator by State Works LED vs Incandescent Bulb Cost Chart and Examples How the LED vs Incandescent Bulb Cost Works Reverse Osmosis Filter Cost Chart and Examples How the Reverse Osmosis Filter Cost Works

Aquarium Guides

Use these guides to check tank volume, heater watts, filter flow, substrate, water changes, and livestock-safe assumptions.

Most useful

Aquarium What Size Heater Do I Need for My Aquarium? Choose aquarium heater wattage from tank gallons, room temperature, target water temperature, and safety margin. Aquarium What Size Aquarium Heater for a 75 Gallon Tank? Estimate heater wattage for a 75 gallon aquarium and decide whether one heater or two smaller heaters makes more sense. Aquarium Aquarium Filter GPH for a 20 Gallon Tank Estimate filter GPH for a 20 gallon aquarium and understand how media, flow loss, stocking, and plants change the target. Aquarium Aquarium Water Change Schedule Guide Plan aquarium water changes by tank size, stocking level, change percentage, replacement-water temperature, and dechlorinator needs. Aquarium How Many Gallons Is My Fish Tank? Calculate aquarium gallons from tank length, width, height, and displacement from substrate or decor. Aquarium Aquarium Canister Filter Size Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the aquarium canister filter size calculator. Aquarium How the Aquarium Canister Filter Size Works Learn how the aquarium canister filter size calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Aquarium Aquarium CO2 Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the aquarium co2 calculator.

More guides

Heater sizing

Aquarium Heater Electricity Cost Chart and Examples How the Aquarium Heater Electricity Cost Works Aquarium Heater Size for 10 Gallon Tank.What Size Heater for a 20 Gallon Aquarium?Aquarium Heater Size for 20 Gallon Tank.Aquarium Heater Size for 40 Gallon Tank.Aquarium Heater Size for 55 Gallon Tank.What Size Heater for a 75 Gallon Aquarium?Aquarium Heater Size for 75 Gallon Tank.Aquarium Heater Size Chart and Examples How the Aquarium Heater Size Works Best Aquarium Heaters by Tank Size Heater Size for 10 Gallon Aquarium Heater Size for 20 Gallon Aquarium

Tank volume and dimensions

Aquarium Stand Weight Chart and Examples How the Aquarium Stand Weight Works Aquarium Volume Chart and Examples How the Aquarium Volume Works Aquarium Weight Chart and Examples How the Aquarium Weight Works Best Aquarium Filters for 20, 40, and 75 Gallon Tanks

Filters and flow

Aquarium Filter Flow Chart and Examples How the Aquarium Filter Flow Works Canister Filter vs. Hang-on-Back Filter

Water changes and care

Aquarium Cycle Ammonia Chart and Examples How the Aquarium Cycle Ammonia Works Aquarium Medication Dosage Chart and Examples How the Aquarium Medication Dosage Works Aquarium Salt Dosage Chart and Examples How the Aquarium Salt Dosage Works Aquarium Water Change Chart and Examples How the Aquarium Water Change Works Aquarium Water Conditioner Dosage Chart and Examples How the Aquarium Water Conditioner Dosage Works

Substrate, stocking, and CO2

How the Aquarium CO2 Works Aquarium Fertilizer Dosing Chart and Examples How the Aquarium Fertilizer Dosing Works Aquarium Lighting Chart and Examples How the Aquarium Lighting Works Aquarium Stocking by Fish Type Chart and Examples How the Aquarium Stocking by Fish Type Works Aquarium Stocking Estimate Chart and Examples How the Aquarium Stocking Estimate Works How Much Gravel or Substrate Does an Aquarium Need?Aquarium Substrate Chart and Examples How the Aquarium Substrate Works

Other guides

Glass Aquarium vs. Acrylic Aquarium

Home Project Guides

Review paint, primer, drywall, flooring, mulch, surface prep, waste, and measurement examples before buying materials.

Most useful

Home Projects How to Calculate Paintable Wall Area Estimate paintable wall area by measuring walls, subtracting large openings, planning coats, and adding a waste allowance before buying paint. Home Projects How Many Gallons of Paint for a 12x12 Room? Estimate paint gallons for a 12x12 room by wall height, coats, openings, paint coverage, and waste allowance. Home Projects Paint for a 12x12 Room: Gallons, Coats, and Buffer Plan paint for a 12 by 12 room using wall height, openings, coats, coverage, primer needs, and touch-up buffer. Home Projects Flooring Waste Factor Guide Learn how much extra flooring to order for simple rooms, closets, diagonal layouts, and patterned material. Home Projects How Many Sheets of Drywall Do I Need? Estimate drywall sheet count from wall and ceiling area, sheet size, waste, and project layout. Home Projects Mulch Depth and Bag Guide Choose a mulch depth and convert landscape area into bags, cubic feet, or cubic yards, with notes on bulk mulch, top-ups, and avoiding excess depth. Home Projects Basement Waterproofing Cost Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the basement waterproofing cost calculator. Home Projects How the Basement Waterproofing Cost Works Learn how the basement waterproofing cost calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate.

More guides

Paint

Best Painting Supplies for Beginners Cabinet Paint Chart and Examples How the Cabinet Paint Works How Much Paint for a 12x12 Room?Paint Coverage Chart and Examples How the Paint Coverage Works Primer Chart and Examples How the Primer Works

Flooring

Flooring Cost Chart and Examples How the Flooring Cost Works How Much Flooring for a 10x12 Room?Stair Carpet Chart and Examples How the Stair Carpet Works Tile Chart and Examples How the Tile Works Wallpaper Chart and Examples How the Wallpaper Works

Drywall

Drywall Sheet Chart and Examples How the Drywall Sheet Works Insulation Chart and Examples How the Insulation Works Spray Foam Cost Chart and Examples How the Spray Foam Cost Works

Concrete

Concrete Chart and Examples How the Concrete Works Gravel Chart and Examples How the Gravel Works Paver Sand Chart and Examples How the Paver Sand Works

Other guides

Closet Shelving Material Chart and Examples How the Closet Shelving Material Works Driveway Sealer Chart and Examples How the Driveway Sealer Works Garden Soil Mix Chart and Examples How the Garden Soil Mix Works Grass Seed Chart and Examples How the Grass Seed Works Leaf Bag Chart and Examples How the Leaf Bag Works Pressure Washer Time and Water Estimate Chart and Examples How the Pressure Washer Time and Water Estimate Works

Finance Guides

Compare payment, payoff, affordability, subscription, and household-budget assumptions before making a money decision.

Most useful

Finance Mortgage Payment Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the mortgage payment calculator. Finance How the Home Affordability Works Learn how the home affordability calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Finance How the Loan Payment Works Learn how the loan payment calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Finance How the Credit Card Payoff Works Learn how the credit card payoff calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Finance Auto Insurance Cost Estimator Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the auto insurance cost estimator. Finance How the Auto Insurance Cost Estimator Works Learn how the auto insurance cost estimator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Finance Car Affordability Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the car affordability calculator. Finance How the Car Affordability Works Learn how the car affordability calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate.

More guides

Mortgage and loans

Home Affordability Chart and Examples Loan Payment Chart and Examples Mortgage Refinance Chart and Examples How the Mortgage Refinance Works Rent vs Buy Chart and Examples How the Rent vs Buy Works

Debt and savings

Credit Card Interest Chart and Examples How the Credit Card Interest Works Credit Card Payoff Chart and Examples Debt Snowball Chart and Examples How the Debt Snowball Works

Cost comparisons

Car Payment Chart and Examples How the Car Payment Works Home Insurance Estimate Chart and Examples How the Home Insurance Estimate Works

Teacher Tool Guides

Plan classroom rewards, behavior systems, fluency checks, grades, attendance, and teacher routines with clearer assumptions.

Most useful

Education PBIS Reward Budget Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the pbis reward budget calculator. Education How the Behavior Reward Cost Works Learn how the behavior reward cost calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Education How the Behavior Incident Rate Works Learn how the behavior incident rate calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Education How the Reading Fluency WPM Works Learn how the reading fluency wpm calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Education How the Grade Percentage Calculator for Teachers Works Learn how the grade percentage calculator for teachers uses its inputs, formula, assumptions, and examples to produce a practical estimate. Education Attendance Percentage Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the attendance percentage calculator. Education How the Attendance Percentage Works Learn how the attendance percentage calculator uses its inputs, formula, assumptions, and examples to produce a practical estimate. Education Behavior Data Trend Chart and Examples See practical examples, chart-style checkpoints, and common mistakes for the behavior data trend calculator.

More guides

PBIS and rewards

Behavior Reward Cost Chart and Examples Classroom Economy Cost Chart and Examples How the Classroom Economy Cost Works PBIS Reward Ideas Under a Budget Sticker/Reward Supply Chart and Examples How the Sticker/Reward Supply Works Token Economy Reward Rate Chart and Examples How the Token Economy Reward Rate Works

Behavior tracking

How the Behavior Data Trend Works Behavior Incident Rate Chart and Examples

Parent contact

Parent Contact Log Frequency Chart and Examples How the Parent Contact Log Frequency Works

Intervention planning

IEP/Intervention Minutes Chart and Examples How the IEP/Intervention Minutes Works Progress Monitoring Growth Chart and Examples How the Progress Monitoring Growth Works Reading Fluency WPM Chart and Examples Reading WCPM Growth Chart and Examples How the Reading WCPM Growth Works Small Group Intervention Schedule Chart and Examples How the Small Group Intervention Schedule Works

Classroom systems

Classroom Donation Wish List Chart and Examples How the Classroom Donation Wish List Works Classroom Seating Group Chart and Examples How the Classroom Seating Group Works Classroom Supply Budget Chart and Examples How the Classroom Supply Budget Works Grade Percentage Calculator for Teachers Chart and Examples

Other guides

Missing Assignment Rate Chart and Examples How the Missing Assignment Rate Works

Charts

Printable charts and example pages are useful when you need a quick visual reference before opening a calculator.

Most useful

Home Air chart Dehumidifier Size Chart by Room Size & Dampness Use this dehumidifier size chart to compare room square footage, dampness level, and estimated pint capacity before opening the calculator. Aquarium chart Aquarium Heater Wattage Chart by Tank Size Use this aquarium heater wattage chart to compare tank gallons, temperature rise, and suggested heater watts before opening the calculator. Home Air chart Air Purifier Room Size Chart Use this air purifier room size chart to compare room volume, CADR, air changes per hour, and related sizing calculators before choosing a purifier. Home Air chart Air Purifier CADR Chart Use this air purifier CADR chart to compare room size, clean air delivery rate, and air changes per hour. Home Projects chart Paint Coverage Chart by Room Size Use this paint coverage chart to estimate paintable wall area, two-coat coverage, and gallons to buy for common room sizes. Costs chart Space Heater Electricity Cost Chart Use this space heater electricity cost chart to compare heater wattage, daily runtime, kWh use, and monthly cost at an example electric rate. Costs chart Electricity Cost per Appliance Chart Use this electricity cost per appliance chart to compare common wattages, run times, and monthly cost ranges. Education chart Grade Percentage Chart Use this grade percentage chart to compare points earned, points possible, extra credit, and common gradebook checks.

More charts

Calculator Explanations

Use these how-it-works pages when you want the formula, assumptions, examples, and common mistakes behind a specific calculator.

How the Air Changes Per Hour Works How the Air Purifier Annual Ownership Cost Works How the Air Purifier Filter Replacement Cost Works How the Air Purifier Size Works How the Air Purifier vs HVAC Filter Cost Works How the Appliance Replacement Savings Works How the Appliance Wattage Cost Works How the Aquarium Canister Filter Size Works How the Aquarium CO2 Works How the Aquarium Cycle Ammonia Works How the Aquarium Fertilizer Dosing Works How the Aquarium Filter Flow Works How the Aquarium Heater Electricity Cost Works How the Aquarium Heater Size Works How the Aquarium Lighting Works How the Aquarium Medication Dosage Works How the Aquarium Salt Dosage Works How the Aquarium Stand Weight Works How the Aquarium Stocking by Fish Type Works How the Aquarium Stocking Estimate Works How the Aquarium Substrate Works How the Aquarium Volume Works How the Aquarium Water Change Works How the Aquarium Water Conditioner Dosage Works