Aquarium Unit Converter
Four two-way converters for the units the hobby mixes constantly: volume, temperature, general hardness, and carbonate hardness. Type in either box of a pair and the other updates.
Type in either side of any pair and its partner updates. Conversions: 1 US gallon = 3.78541 L, °C = (°F − 32) × 5⁄9, 1 dGH = 17.848 ppm CaCO₃, and 1 meq/L = 2.8 dKH.
Where each unit shows up
Gallons and liters collide the moment you buy equipment: American tanks and dosing labels use US gallons, while European gear, medication instructions, and most fertilizer math use liters. Temperature splits the same way — heater dials and forum advice from the US read in °F, but species care sheets and scientific references usually quote °C. Having both on hand avoids the classic mistake of setting a heater to a number from the wrong scale.
The hardness pairs are where test kits and articles genuinely disagree. Liquid GH kits usually count degrees (dGH), while strip tests and water utility reports use ppm CaCO₃ — the same measurement at 17.848 ppm per degree. For buffering capacity, freshwater keepers talk in dKH, but reef alkalinity discussions and some kits report meq/L, where 1 meq/L equals 2.8 dKH. Livestock requirements are published in all four, so converting before comparing keeps you from chasing a mismatch that was never real.