Start with net water
Real capacity is lower than the number on the tank once glass, substrate and décor are included.
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Plan a healthier aquarium with clear numbers.
Twenty-four practical calculators for tank setup, maintenance, water preparation, equipment and running cost—built for litres and gallons.
24 live tools3 volume systems0 personal data stored
Calculator suite
Choose a tool. Get an answer.
Every result updates as you type. Switch tools without losing your place.
Live calculator
Updates instantlyAquarium volume calculator
Calculate gross tank capacity in litres, US gallons and UK gallons.
Gross volume182.3 L48.1 US gal · 40.1 UK gal
Gross volume does not subtract glass, substrate, rocks or equipment.
Tool 1 of 8
Built for real tanks
Useful estimates, without pretending every aquarium is the same.
Each tool shows its assumptions and keeps metric, US and UK units clear. Results are planning estimates—not a replacement for manufacturer guidance or experienced aquatic advice.
Size equipment conservatively
Filters and heaters lose performance in real setups. Use the result as a baseline, then check the product chart.
Check the final setup
Livestock, room temperature, maintenance and aquascape choices can all change what your aquarium needs.
Common questions
Before you fill the tank
How accurate is the aquarium volume calculator?+
It accurately calculates geometric volume from the dimensions entered. Actual water volume is lower because glass, substrate, rocks, wood and equipment occupy space.
Should I use US or UK gallons?+
Product labels in the United States normally use US gallons. UK gallons are larger. Our results show both and always include litres.
Can I use these results to choose fish?+
Use the tools to understand water volume and equipment capacity, then research the adult size, group needs, temperament and water requirements of every species before purchasing.
Does AquaRithmetic store my measurements?+
No. Calculations run in your browser and the current version does not save or transmit the numbers you enter.
About AquaRithmetic
Small tools for better aquarium decisions.
AquaRithmetic is an independent calculator library for freshwater, planted and marine aquarium planning. We focus on transparent formulas, clear units and practical caveats. Content is educational and results should be confirmed against equipment instructions and species-specific care guidance.