Aquarium Calculators & Tools
Tank volume, pond gallons, substrate weight, heater wattage, and fish compatibility — everything you need to plan and maintain a healthy aquarium or pond.
5 free calculators — no sign-up required
Why Use Our Calculators?
Accurate Calculations
Industry-standard formulas verified by aquarium professionals.
Easy to Use
Simple interfaces designed for beginners and experienced aquarists alike.
Mobile Friendly
Fully responsive — use at the store, next to your tank, or anywhere.
100% Free
No sign-up, no limits, no hidden fees. Just open and calculate.
Frequently Asked Questions
What aquarium calculators are available?
FishStores.org offers five free calculators: a Fish Tank Volume Calculator for rectangular, bow front, and cylinder aquariums; a Pond Volume Calculator for koi ponds and water features; a Fish Compatibility Checker with a visual matrix for freshwater species; a Substrate Calculator for sand, gravel, and aqua soil amounts; and a Heater Size Calculator that recommends the right wattage based on your tank volume and room temperature.
Are these aquarium calculators free to use?
Yes, all five calculators are completely free with no sign-up, no account creation, and no usage limits. Just open the tool and start calculating — results appear instantly.
How accurate are the aquarium calculations?
Our calculators use industry-standard formulas trusted by aquarium professionals and hobbyists alike. Tank volume formulas account for different shapes, substrate calculations factor in material density, and heater sizing follows widely accepted wattage-per-gallon guidelines adjusted for the temperature differential between your room and target water temperature.
Can I use these tools on my phone?
Absolutely. Every calculator is fully responsive and works on phones, tablets, and desktops. The interfaces are optimized for touch input so you can use them at the store, next to your tank, or anywhere you have a browser.