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Tank Weight Calculator

Add up water, substrate, decor and the empty tank itself to get the total weight your floor or stand needs to support once everything is filled.

Your numbers
Gallons — use the Tank Volume Calculator if you don't know this
From the manufacturer spec sheet; leave blank to estimate
Use the Substrate Calculator if unsure
Water
Empty tank
Substrate
Decor

Fill the tank in place, never before moving it

Fill the tank in place, not before moving it — even a partially filled tank is far too heavy and unstable to move safely.

How this calculator works

Total setup weight is simply the sum of everything in and around the tank once it's full: the empty glass or acrylic tank itself, the water (fresh water weighs about 8.34 lb per gallon; saltwater is slightly denser at roughly 8.56 lb per gallon because of the dissolved salt), the substrate, and any rock, driftwood or heavy decor.

If you don't know your empty tank weight

Manufacturer spec sheets list this for most standard glass tanks, and it's worth looking up for anything over 40 gallons. If you can't find it, this calculator estimates roughly 1.4 lb of glass per gallon of capacity as a placeholder — a reasonable ballpark for a standard-thickness glass tank, but acrylic tanks and thick-glass or euro-braced tanks can weigh meaningfully more or less.

What to do with the total

Once you have a total weight, run it through the Stand & Floor Load Calculator along with your tank's footprint to check it against a typical residential floor load allowance, especially for anything above 75–90 gallons or on an upper floor.

Source: Water density figures (8.34 lb/gal fresh, 8.56 lb/gal saltwater) are standard physical reference values for water at typical room/aquarium temperature.

Frequently asked questions

Is saltwater really heavier than freshwater?

Yes, slightly — about 8.56 lb per gallon versus 8.34 lb per gallon for fresh water, a roughly 2.6% difference from the dissolved salts. It's a small difference per gallon but adds up on a large reef system.

Does the stand's own weight matter?

For floor-load purposes, yes — add the stand's weight to the total if you're checking against a floor rating. For checking whether the stand itself can hold the tank, check the stand's rated capacity separately against the tank+water+substrate+decor total from this calculator.

Why does my calculated weight seem lower than the tank's spec sheet?

Spec sheets sometimes quote a rounder, more conservative number, or include the stand. If you have the exact manufacturer figure for your tank, always use that over this calculator's estimate.

More Tank Setup & Sizing calculators

Aquarium Glass Thickness Calculator Aquarium Substrate Calculator Fish Tank Dimensions & Size Chart Calculator

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