🐠 Aquarium Volume Calculator
Measure the inside length, width and height of your tank in inches (or diameter and height for a cylinder).
How the Aquarium Volume Calculator works
Volume in cubic inches is divided by 231 to get US gallons. Water weighs about 8.34 lb per gallon, which matters when choosing a stand.
Step-by-step calculation
- 1Measure inside length, width and height.
- 2Multiply for cubic inches.
- 3Divide by 231 for US gallons.
Worked example
A 48 × 13 × 21 inch tank holds 13,104 ÷ 231 ≈ 56.7 US gallons (214.7 L) when filled to the brim; the water weighs about 473 lb.
Aquarium Volume Calculator examples
| Length or diameter (in) | Tank volume |
|---|---|
| 24 | 28.4 US gallons |
| 36 | 42.5 US gallons |
| 48 | 56.7 US gallons |
| 60 | 70.9 US gallons |
| 72 | 85.1 US gallons |
Other inputs kept at the calculator's default values. Results calculated by this calculator.
Why use an Aquarium Volume Calculator?
Dose medicine, size filters and choose a safe stand.
Important factors that can affect your results
- Substrate and decor reduce water volume.
- Inside vs outside measurements.
- Water weight on the stand.
Frequently asked questions
Why is my "55 gallon" tank less?
Substrate, decorations and the gap below the rim reduce the real water volume by roughly 10–20%.
Does the stand need to hold the full weight?
Yes — plus the tank, rocks and equipment. A filled tank weighs roughly 10 lb per gallon in total.
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Last reviewed November 2026 · How we build and check our tools · Report a problem