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Fish Tank Volume Calculator

Fish Tank Surface Area Calculator

Surface area

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Enter your tank dimensions to see the volume.

Did we solve your problem?

Work out the water surface area of your aquarium, which affects oxygen exchange. Enter the dimensions to see the surface area and the full volume.

Why surface area matters

The water surface is where oxygen enters and carbon dioxide leaves, so it is length times width for a rectangular tank. A wide, shallow tank holds more oxygen than a tall, narrow one of the same volume.

Water surface area of common tanks

Length × Width (cm)Water surface area (cm²)in²ft²
30 × 309001400.97
40 × 251,0001551.08
45 × 301,3502091.45
60 × 301,8002791.94
60 × 301,8002791.94
80 × 352,8004343.01
100 × 404,0006204.31
120 × 404,8007445.17
120 × 506,0009306.46
150 × 507,5001,1638.07

Calculated with the same formula as the calculator above. Values are rounded.

Water surface area

length width

The water surface is length times width. Adjust the sides to see the area.

Surface area = 1,800 cm²

Formula

V = length × width × height

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Frequently asked questions

How do I calculate fish tank surface area?
For a rectangular tank, multiply length by width. That is the top opening where gas exchange happens.
Why is surface area important for fish?
A larger surface lets more oxygen dissolve, which supports more fish and healthier water.
Is a tall tank worse for oxygen?
A tall, narrow tank has less surface for its volume, so it holds less oxygen than a wide tank of the same size.
How does surface area relate to stocking?
Some aquarists stock by surface area rather than volume, allowing roughly a set length of fish per area of surface.
What units can I use in this calculator?
You can switch between centimetres, millimetres, inches, feet and metres at any time. Enter all dimensions in the same unit and the result updates instantly.
Does the result include substrate and decoration?
The figure is the full internal capacity. Subtract roughly 10 to 15 percent for substrate, rocks and the gap you leave at the top to estimate the real water volume.
How accurate is this fish tank calculator?
It uses the exact geometric formula for each shape, so the result is accurate for the dimensions you enter. Measure the inside of the tank for the best accuracy.
Is this calculator free to use?
Yes. It is completely free, needs no sign-up, and works on phones, tablets and desktops.

Related guides

Learn the core ideas behind fish tank volume before or after using the calculator.