Guides
How Much Aquarium Substrate Do I Need?
Work out exactly how much gravel, sand or aqua soil your tank needs, the right depth, and how many bags to buy.
Read more →Fish Tank Water Volume Calculator
Volume
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Enter your tank dimensions to see the volume.
Did we solve your problem?
Calculate the water volume of your aquarium, not just its full capacity. Enter the dimensions and adjust for the space your substrate and decor take up.
Tank volume vs water volume
The calculated volume is the full capacity. The actual water volume is lower because substrate, rocks and decor displace water and you leave a gap at the top. Subtract about 10 to 15 percent for a realistic figure.
Volume at a glance
Drag to fill a 60 by 30 by 30 cm (54 L) tank and watch the volume change.
50% full = 27 L
Formula
V = length × width × height Related calculators
Frequently asked questions
How do I calculate water volume in a fish tank?
Calculate the full volume, then subtract roughly 10 to 15 percent for substrate, rocks and the top gap.
How much water does my tank actually hold?
Usually 85 to 90 percent of the calculated capacity, once substrate and decor are in place.
Why does water volume matter?
Medication and conditioner doses are based on the real water volume, so an accurate figure keeps treatments safe.
Does gravel reduce water volume?
Yes. A few centimetres of substrate across the base can displace several litres of water.
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.
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