Aquarium Volume Calculator
Calculate real water volume in an aquarium after substrate, with the filter turnover it needs.
Your tank holds less than it says
A '200 litre' tank filled to 5 cm below the rim with 5 cm of substrate holds closer to 165 litres. Every dosing instruction — medication, fertiliser, water conditioner — is per litre of actual water, so overdosing by 20% is easy and, with some medications, dangerous for fish.
The formula
Water = length × width × (height − substrate depth)
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Aquarium Volume Calculator
- Fill in each field with your own figures — the defaults are only there as an example.
- The result updates as you type, so there is no button to press.
- Check the breakdown under the main result for the supporting numbers.
- Use the copy button to take the result with you, or share the link to reload the same inputs.
Aquarium Volume Calculator — frequently asked questions
Is this aquarium volume calculator free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
How accurate is the result?
The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.
Can I use it on my phone?
Yes. The page is responsive, weighs a few kilobytes and works offline once loaded, so it behaves the same on a phone as on a desktop.
What people search for
This page answers each of these searches. They are the exact phrases visitors use to find the aquarium volume calculator.
- aquarium volume calculator
- aquarium capacity
- tank water volume
- how many gallons is my tank
- fish tank litres
About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 23, 2026 · Calculation runs client-side · No data collected · Report an error