This aquarium weight calculator adds up water, tank, substrate, rock, sump and stand to estimate the total weight of a filled tank. As a quick check, freshwater weighs about 8.35 lb per gallon and saltwater about 8.55 lb. A complete setup comes out heavier than the water alone. Top Shelf Aquatics puts a typical 55-gallon setup at 600–700 lb, and says a filled reef runs closer to 10–11 lb per gallon.
Guide: about 1 lb per gallon, up to twice that for sand.
Aquarium Weight Chart by Tank Size
The figures below are published estimates for standard glass tanks, and real weights vary by maker and glass thickness. Water weight is calculated at 8.345 lb per gallon.
| Tank | Empty glass (lb) | Water only (lb) | Typical filled system (lb) |
|---|---|---|---|
| 10 gal | 11 | 83 | 110–130 |
| 20 gal | 25 | 167 | 215–250 |
| 29 gal | 40 | 242 | 310–360 |
| 40 gal breeder | 58 | 334 | 430–500 |
| 55 gal | 78 | 459 | 600–700 |
| 75 gal | 140 | 626 | 850–1,000 |
| 90 gal | 160 | 751 | 1,000–1,200 |
| 125 gal | 206 | 1,043 | 1,400–1,650 |
| 180 gal | 430 | 1,502 | 2,000–2,300 |
How the Aquarium Weight Calculator Works
- Water: volume plus any sump water, multiplied by 8.345 lb per gallon for fresh or 8.554 lb for salt. It assumes a completely full tank, which overstates water slightly and errs on the safe side.
- Empty tank: interpolated from published weights for standard glass tanks. The acrylic option halves that figure. This is our rough assumption, because thick acrylic tanks vary widely, so use the maker's weight if you have it.
- Everything else: the substrate, rock and stand weights you enter. Sand and gravel run about 85–105 lb per cubic foot.
Aquarium Weight and Floor Safety
This calculator can't tell you what your floor will hold, since that depends on the joists, span and condition of the building. Top Shelf Aquatics suggests that tanks up to about 55 gallons usually sit fine on a solid floor near a load-bearing wall, while 75 gallons and up should run across the joists, with a professional consulted when in doubt.
- Check that the stand is rated for your total and sits level.
- Remember the weight sits on a small footprint, so it concentrates the load.
- Take extra care upstairs, over a crawl space or on an old floor.
- Move a tank only when it's empty. Water and sand are what make it dangerous.
When you are planning the whole setup, the aquarium size calculator gives you the volume from the tank's dimensions.
Aquarium Weight FAQ
How much does a 55 gallon fish tank weigh?
About 459 lb of fresh water plus about 78 lb for the empty glass tank, or roughly 540 lb before substrate and decor. A complete system is commonly estimated at 600 to 700 lb.
How much does a 75 gallon fish tank weigh?
About 626 lb of fresh water plus about 140 lb of glass, or roughly 770 lb. With substrate, decor and equipment, a common estimate is 850 to 1,000 lb.
Is saltwater heavier than freshwater?
Yes, slightly. Saltwater is about 8.55 lb per gallon compared with 8.35 lb for fresh, but rock and sand are usually what make a reef noticeably heavier.
Can I put a 55 gallon tank on the second floor?
Many people do, but it depends on the building. Place it near a load-bearing wall and across the joists, and ask a professional if you are unsure.
How much does a gallon of water weigh?
About 8.35 lb for a US gallon of fresh water and about 8.55 lb for salt water.
How Accurate Is This Aquarium Weight Estimate?
It's an estimate for planning, using published empty-tank weights, standard water weights and the numbers you enter. Published figures disagree, so we favor conservative totals and show the ranges. This tool isn't a structural assessment. FishCare AI didn't weigh tanks for this page.