Aquarium Volume Calculator
Tank volume, stocking level and water changes.
Enter your values
Enter the length in in.
Enter the width in in.
Enter the height in in.
Enter the weekly water change in %.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- 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
At a glance
| What it does | Tank volume, stocking level and water changes. |
|---|---|
| Category | Pets |
| Inputs needed | Length, Width, Height, Weekly water change |
| Main output | Gross volume |
| Formula | Gallons = L × W × H (in) ÷ 231 |
| Cost | Free — no sign-up, no download |
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.
Inputs explained
- Length(in)
- Enter the length in in.
- Width(in)
- Enter the width in in.
- Height(in)
- Enter the height in in.
- Weekly water change(%)
- Enter the weekly water change in %.
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.
What do I need to enter into the Aquarium Volume Calculator?
Just 4 values: length, width, height, weekly water change. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Aquarium Volume Calculator work out the answer?
Tank gallons equal length × width × height in inches divided by 231, minus roughly 10% for substrate and decor. It applies the formula Gallons = L × W × H (in) ÷ 231 and shows the working so you can check each step by hand.
Is the Aquarium Volume Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.