Result
19.9 gallons
A 24 x 12 x 16 inch rectangular tank holds about 19.9 gallons before displacement.
- Gallons
- 19.9 gal
- Liters
- 75.5 L
Use inside dimensions when possible
Glass thickness, substrate, rock, and decorations reduce actual water volume. For dosing, a slightly conservative estimate is safer.
Rectangular tanks only in V1
This launch calculator is designed for standard rectangular aquariums. Bow-front and cylinder tanks need different formulas.
Formula and assumptions
This calculator uses the inputs above to turn a practical planning question into a usable estimate. The result should be treated as a starting point, because product ratings, room conditions, material waste, and real-world use can vary.
Example calculation
Example inputs: Tank length: 24 inches; Tank width: 12 inches; Tank height: 16 inches. With those values, the calculator returns 19.9 gallons. A 24 x 12 x 16 inch rectangular tank holds about 19.9 gallons before displacement.
Common planning mistakes
Avoid using rough guesses for every input, forgetting waste or safety margin, and treating the estimate as a guaranteed final number. Measure the space, round up when buying materials or equipment, and compare the result with product labels or project instructions.
FAQs
Aquarium Volume Calculator questions
Why divide by 231?
One US gallon contains 231 cubic inches.
Is this exact water volume?
No. It estimates empty tank capacity before displacement from substrate, hardscape, and equipment.