Tank Capacity Calculator
Tank Volume Calculator works out Total capacity and Volume at the measured depth from Tank shape, Length and Width. The default figures on this page give total capacity of 44.88 US gal; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
4 steps
- Shape: 0.9144 x 0.4572 x 0.4064 m.
- Capacity = 0.169901 m3 = 169.9 L = 44.88 US gal = 6 cu ft.
- No fill depth was given, so only the full capacity is reported.
- Full, the contents weigh 0.169901 m3 x 1000 kg/m3 = 169.9 kg (374.6 lb), before the weight of the tank, substrate or rock.
Its 4 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
Keep this result
Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the Tank Volume Calculator calculates
Computes the capacity of a tank, cistern or aquarium in litres, US and imperial gallons, cubic feet and cubic metres for eight shapes, and the volume actually held at a measured fill depth.
How to use this Tank Volume Calculator
Enter Tank shape, Length, Width and Height (straight side). Total capacity updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Total capacity, Volume at the measured depth and Space still free.
The method follows Closed-form solid geometry: prism, cylinder, sphere, spherical cap and circular segment, NIST Special Publication 811, Guide for the Use of the International System of Units and Researched engineering contract R1767 (aquarium volume, V = L x W x H).
Rectangular aquarium 36 x 18 x 16 inches example
With Tank shape: rectangular, Length: 36, Width: 18, Height (straight side): 16, the calculator returns Total capacity: 44.8831169, Total capacity: 6. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Total capacity, Volume at the measured depth and Space still free. The inputs you can vary are Tank shape, Length, Width, Height (straight side), Diameter and Cone height.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How to calculate tank volume?
Computes the capacity of a tank, cistern or aquarium in litres, US and imperial gallons, cubic feet and cubic metres for eight shapes, and the volume actually held at a measured fill depth. Open “How this is worked out” beside the result to see each step for your own figures.
How many gallons is my tank calculator?
It needs Tank shape, Length, Width, Height (straight side), Diameter and Cone height. Nothing else is required, and the figures stay in your browser.
How to calculate aquarium tank volume?
The result gives Total capacity, Volume at the measured depth, Space still free, Fill level and Weight of the contents when full, each labelled with its unit so the figure can be read on its own.
How to figure tank volume in gallons?
The page opens with worked default figures: total capacity of 44.88 US gal. Replace them with your own and every figure updates as you type.
What information do I need for the Tank Volume Calculator?
You need Tank shape, Length, Width, Height (straight side), Diameter, Cone height, Measured fill depth and Unit for the dimensions. The page opens with default figures that give total capacity of 44.88 US gal, so you can see the scale before entering your own.
What does this Tank Volume Calculator show?
It shows Total capacity, Volume at the measured depth, Space still free, Fill level and Weight of the contents when full, with the working and any warnings for your entries.