Aquarium Volume Calculator

Rectangular tanks: volume (L) = length × width × height ÷ 1000 when dimensions are in centimeters (inches are converted first). Cylindrical tanks: volume = π × radius² × height ÷ 1000.

Actual water volume is less than total volume once you account for substrate, rocks, and equipment displacement. Use this as a gross tank size estimate.

Example: 60 cm × 30 cm × 40 cm = 72 liters (about 19 US gallons). In US units, a 24 × 12 × 16 in tank is about the same size.

Sump and refugium water adds to total system volume for dosing and evaporation top-off even though fish stocking rules usually count display gallons only.

Bow-front and hex tanks curve — rectangular L×W×H overestimates volume; use manufacturer spec sheets for bowed glass profiles.

Freshwater stocking rules cite roughly one inch of adult fish per net gallon — subtract rock and substrate displacement from the 19 gal default rectangle before applying inch-per-gallon heuristics.

Cylinder mode uses radius and height — measure inside diameter halved for radius, not outer trim ring dimensions printed on retail packaging.

Marine systems often need 20–30% less fish biomass than freshwater rules suggest — salinity and filtration change acceptable bioload beyond gross gallon count.

Switching the unit toggle remaps length fields between inches and centimeters without changing underlying volume — match the tape measure you actually used on the tank.

Compare gross volume here against net fill after substrate — many aquarists subtract 10–15% displacement before applying inch-per-gallon stocking heuristics.

Retail tank labels sometimes round gallons marketing-up — measuring inside length, width, and height yourself beats trusting a sticker volume on the box.

Protein skimmers and hang-on-back filters displace little volume compared to deep sand beds — subtract displacement mentally when stocking sensitive reef fish.

Heater and canister filter chambers hold water outside the display tank — include sump volume only when calculating total system water for dosing pumps.