All Aquarium Calculators

Free, no-login aquarium calculators built on community-verified rules. Every number shows its source and confidence grade; disagreements are shown, not hidden.

• Fish Tank Substrate Calculator — Gravel and sand amount by weight, volume and bag count — with depth warnings for anaerobic risk.
• Aquarium Volume Calculator — Gallons, liters and true water volume for any tank shape, with footprint and full-weight readings.
• Water Change Calculator — Gallons to swap per change, and the change schedule that dilutes your nitrate reading to target.
• Aquarium Heater Calculator — Heater watts by tank size, with open-top and cold-room adjustments and dual-heater guidance.
• Aquarium Dosing Calculator — Milliliters, teaspoons or packets — from the manufacturer label, checked and dated.
• Aquarium Light Calculator — A lumens-and-watts ballpark with honest error bars — and the PAR targets that actually grow plants.