Free Aquarium Calculators & Tools

Name: AquaLens
Author: AquaLens

Quick, free tools for everyday aquarium math — no sign-up needed. Sign in with your AquaLens account to run these against your real tanks.

Most used

Get your aquarium's volume in gallons and liters from its length, width, and height — rectangular and cylindrical tanks.

Convert gallons ↔ liters, °F ↔ °C, dGH ↔ ppm, and dKH ↔ meq/L — the everyday conversions every aquarist needs.

Work out what percentage water change brings nitrate, ammonia, or any parameter down to your target — accounting for your source water.

Enter your ammonia, nitrite, and nitrate readings to see where your cycle stands and what happens next.

Estimate dissolved CO₂ in a planted tank from pH and carbonate hardness, with safe target ranges.

Will that rock raise your pH? How common aquarium rocks and woods affect pH, KH, and GH.

Convert doses between mL, pumps, teaspoons, and grams, and scale any product label's “X mL per Y gallons” to your exact tank volume.

Check whether your filter's real-world flow gives your tank the turnover it needs — freshwater, planted, or reef.

Find the right heater wattage for your tank volume and the temperature rise you need above room temperature.

Estimate your tank's monthly electricity and water bill from your equipment wattage and water change routine.

Convert between specific gravity and ppt for saltwater and reef tanks, with the standard reef target range for reference.

How much salt mix to add to reach your target salinity — for new saltwater batches and top-ups.

Plan a stable community around adult size, social needs, swimming room, filtration, and maintenance—not an arbitrary fish count.