How Much Does a Fish Tank Weigh? 10, 20, 40, 55 and 75 Gallon Weights

Water is much heavier than most people expect. A tank that looks like a piece of furniture when it is empty can weigh as much as a small car engine once it is filled, decorated and running. Before you put an aquarium on a stand, a dresser or an upstairs floor, it is worth knowing exactly how much it will weigh.

This guide gives you the full weight of the most common tank sizes, shows how that figure is built up from the water, the glass and the substrate, and explains how to calculate the weight of any tank, including saltwater setups.

The quick answer

A filled freshwater aquarium weighs roughly 10 pounds per US gallon once you include the water, the glass and a normal gravel bed. The water alone is the biggest part:

• 1 US gallon of fresh water weighs 8.34 lb (3.79 kg)
• 1 litre of fresh water weighs 1 kg (2.2 lb)

So a 55 gallon tank holds about 459 lb of water before you add anything else, and the whole setup comes to roughly 600 lb.

Fish tank weight chart

The table below uses the standard glass tank dimensions for each size, the weight of the rated gallons of fresh water, a typical empty weight for a standard glass tank, and a 2 inch gravel bed calculated from the tank footprint. Empty weights vary by brand and glass thickness, so treat the totals as close estimates, not exact figures.

Tank size	Dimensions (in)	Water	Empty glass tank	2 in gravel	Approx. total
10 gallon	20 x 10 x 12	83 lb	11 lb	22 lb	116 lb (53 kg)
20 gallon high	24 x 12 x 16	167 lb	25 lb	31 lb	223 lb (101 kg)
20 gallon long	30 x 12 x 12	167 lb	25 lb	39 lb	231 lb (105 kg)
29 gallon	30 x 12 x 18	242 lb	40 lb	39 lb	321 lb (146 kg)
40 gallon breeder	36 x 18 x 16	334 lb	58 lb	70 lb	462 lb (209 kg)
55 gallon	48 x 13 x 21	459 lb	78 lb	68 lb	604 lb (274 kg)
75 gallon	48 x 18 x 21	626 lb	140 lb	94 lb	859 lb (390 kg)
125 gallon	72 x 18 x 21	1,042 lb	206 lb	140 lb	1,389 lb (630 kg)

Rocks, driftwood, a canopy and equipment add more on top. Large rockwork in particular can add 20 to 50 lb to a mid-size tank.

How much does a 10 gallon fish tank weigh?

A 10 gallon tank holds about 83 lb of water. The empty glass tank weighs around 11 lb, and a 2 inch layer of gravel over its 20 x 10 inch footprint adds about 22 lb. All together, a filled 10 gallon tank weighs roughly 116 lb (53 kg). That is light enough for a sturdy desk or dresser, but it is still far more than most shelves are built to hold, so check the furniture rating before you fill it.

How much does a 20 gallon fish tank weigh?

Both 20 gallon shapes hold about 167 lb of water. The difference is the footprint. A 20 gallon high (24 x 12 inches) needs about 31 lb of gravel for a 2 inch bed and comes to roughly 223 lb (101 kg) in total. A 20 gallon long (30 x 12 inches) has a larger base, so it takes about 39 lb of gravel and weighs around 231 lb (105 kg). Either way, a filled 20 gallon tank weighs more than an adult person, which is why it needs a proper aquarium stand rather than a bookshelf.

How much does a 40 gallon fish tank weigh?

A 40 gallon breeder is wide and deep (36 x 18 inches), so it holds a lot of substrate as well as water. Expect around 334 lb of water, 58 lb of glass and 70 lb of gravel, for a total of about 462 lb (209 kg). A 40 gallon long (48 x 12 x 16 inches) has a similar water weight but a narrower base.

How much does a 55 gallon fish tank weigh?

The 55 gallon is one of the most popular sizes, and one of the most underestimated. It holds about 459 lb of water. With a typical 78 lb glass tank and about 68 lb of gravel, a filled 55 gallon weighs roughly 604 lb (274 kg). Spread over a 48 x 13 inch footprint, that is a heavy, concentrated load, so a dedicated aquarium stand is essential.

How much does a 75 gallon fish tank weigh?

A 75 gallon tank shares the 4 foot length of a 55 but is 18 inches deep, so it holds much more. The water alone weighs about 626 lb, the glass around 140 lb and a 2 inch gravel bed about 94 lb, for a total close to 859 lb (390 kg). With rockwork and a stand, a 75 gallon setup can approach half a ton.

How much does a 125 gallon fish tank weigh?

A 125 gallon tank (72 x 18 x 21 inches) holds about 1,042 lb of water. Add roughly 206 lb of glass and 140 lb of gravel, and the filled tank weighs around 1,389 lb (630 kg). At this size you should plan the position carefully and consider asking a builder about the floor.

How to calculate the weight of any fish tank

You can work out the weight of a tank of any size or shape in three steps:

1. Find the water volume. Use the fish tank volume calculator to get the volume in gallons or litres from your tank’s measurements and shape.
2. Convert the volume to weight. Multiply US gallons by 8.34 to get pounds, or litres by 1 to get kilograms.
3. Add the tank and everything in it. Add the empty tank weight (check the manufacturer’s listing), the substrate and any rock or wood.

The fish tank weight calculator does all three steps for you and also gives the result in kilograms and pounds.

For the substrate, the aquarium substrate calculator turns your tank footprint and bed depth into an exact weight of gravel or sand.

Saltwater tanks weigh more

Salt water is slightly denser than fresh water, at about 1.025 kg per litre. That adds around 2.5 percent to the water weight, so a 55 gallon reef tank holds about 470 lb of water instead of 459 lb. Reef tanks also tend to carry much more rock and sand than freshwater tanks, so the real difference is usually larger than the water alone suggests.

Will my stand and floor hold it?

• Use a stand rated for the full weight. A stand designed for your tank size spreads the load evenly under the glass frame. Furniture that was not built for it can sag over time, which stresses the seams.
• Level the stand first. An uneven base concentrates the load on one corner of the glass. Check it with a spirit level before you add water.
• Think about the floor for larger tanks. Residential floors in the US are typically designed for about 40 lb per square foot of live load spread across a room. A filled 55 gallon tank puts around 600 lb on a footprint of about 4.3 square feet, so place large tanks across the floor joists and close to a load-bearing wall. For tanks of 75 gallons and up, especially on an upper floor, it is worth asking a builder or structural engineer.

Frequently asked questions

How much does a gallon of water weigh? One US gallon of fresh water weighs 8.34 lb (3.79 kg). One UK gallon weighs about 10 lb (4.55 kg), because a UK gallon is larger.

How much does a 20 gallon fish tank weigh empty? A standard glass 20 gallon tank weighs roughly 25 lb empty. Rimless and thicker-glass tanks can weigh more.

Why does my tank weigh less than the chart? The chart uses the tank’s rated gallons. Most tanks hold slightly less water than their rated size once you allow for glass thickness, substrate and the gap at the top, so the real water weight is usually a little lower.

Can I put a fish tank on a dresser? Small tanks of 5 to 10 gallons can sit on a solid dresser that is rated for the weight. From 20 gallons upwards, use a purpose-built aquarium stand.

Knowing the weight before you fill the tank keeps your fish, your furniture and your floor safe.