Aquarium Volume Calculator
Tank volume, stocking level and water changes.
Enter your values
ⓘ Live results
Results
- Gross volume
- 78.5 US gallons
- Actual water volume
- 70.7 gallons (268 L)
- Weekly water change
- 17.7 gallons
- Filter turnover target
- 353 gph (5× per hour)
- Approximate filled weight
- 747 lb
Quick answer
Tank gallons equal length × width × height in inches divided by 231, minus roughly 10% for substrate and decor.
Gallons = L × W × H (in) ÷ 231
How to use the Aquarium Volume Calculator
- 1Measure the tank's inside dimensions in inches.
- 2Enter your weekly water change percentage.
- 3Read volume, turnover and weight.
Worked example
Using the values the calculator loads with:
Inputs
- Length48 in
- Width18 in
- Height21 in
- Weekly water change25 %
Results
- Gross volume78.5 US gallons
- Actual water volume70.7 gallons (268 L)
- Weekly water change17.7 gallons
- Filter turnover target353 gph (5× per hour)
- Approximate filled weight747 lb
Frequently asked questions
Why is actual volume lower?
Substrate, rock, decor and the gap below the rim typically take 10–15% of the nominal volume.
How strong should my filter be?
Aim for 4–6× tank volume per hour for community tanks, higher for messy or heavily stocked setups.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.