Aquarium Weight Calculator
The aquarium weight calculator estimates how much your tank weighs when filled. Enter your water volume to get the weight of the water plus an approximate total filled weight including the tank, rock and substrate. It’s an essential check before you set up a new build on a stand, floor or piece of furniture.
Water is heavier than most people expect at 8.34 pounds per gallon, and a filled reef system typically runs closer to 10 to 11 pounds per gallon once glass, rock and sand are added. Confirm your floor and stand can safely carry the load, especially for tanks of 75 gallons or more.
Formula: Water weight (lb) = gallons × 8.34
Filled aquarium weight chart
Water weighs 8.34 pounds per US gallon before you add the tank, stand, substrate, rock and equipment. Use the ranges below for early floor and stand planning, then enter your measured water volume and substrate weight in the calculator above. Actual tank weight varies by glass thickness, acrylic construction, cabinetry and aquascape.
| Tank size | Water only | Typical empty tank | Typical filled setup |
|---|---|---|---|
| 10 gallon | 83 lb | 10–15 lb | 110–130 lb |
| 20 gallon | 167 lb | 25–30 lb | 215–250 lb |
| 29 gallon | 242 lb | 40–45 lb | 310–360 lb |
| 40 gallon | 334 lb | 55–60 lb | 430–500 lb |
| 55 gallon | 459 lb | 75–80 lb | 600–700 lb |
| 75 gallon | 626 lb | 140–150 lb | 850–1,000 lb |
| 90 gallon | 751 lb | 160–180 lb | 1,000–1,200 lb |
| 100 gallon | 834 lb | 180–220 lb | 1,150–1,350 lb |
| 125 gallon | 1,043 lb | 200–250 lb | 1,400–1,650 lb |
| 180 gallon | 1,501 lb | 300–350 lb | 2,000–2,300 lb |
How much do common fish tank sizes weigh?
How much does a 10 gallon fish tank weigh with water?
Ten gallons of water weigh about 83 pounds. After adding the empty aquarium, substrate and basic equipment, a typical 10 gallon fish tank weighs roughly 110 to 130 pounds.
How much does a 20 gallon aquarium weigh when filled?
Twenty gallons of water weigh about 167 pounds. A filled 20 gallon aquarium usually weighs about 215 to 250 pounds once the tank, substrate, decor and equipment are included.
How much does a 55 gallon fish tank weigh?
A 55 gallon aquarium contains about 459 pounds of water. A complete setup commonly weighs 600 to 700 pounds, depending on the tank, stand, rock and substrate.
How much does a 75 gallon aquarium weigh?
Seventy-five gallons of water weigh about 626 pounds. With a typical glass tank, stand, substrate, rock and equipment, plan for a total of roughly 850 to 1,000 pounds.
How much does a 100 gallon fish tank weigh?
One hundred gallons of water weigh about 834 pounds. A complete 100 gallon aquarium commonly weighs about 1,150 to 1,350 pounds and should be evaluated carefully for floor and stand support.
These are planning estimates, not structural-engineering advice. Large aquariums concentrate substantial loads in a small footprint; consult a qualified professional when floor capacity is uncertain.
Frequently Asked Questions
How much does a filled aquarium weigh?
Water weighs about 8.34 pounds per gallon, so the water alone in a 55 gallon tank is about 460 pounds. Add the tank, rock and substrate and the real filled weight is higher, often around 10 to 11 pounds per gallon. Enter your volume above for an estimate.
Can my floor hold a fish tank?
Most tanks up to about 55 gallons are fine on a solid floor near a load-bearing wall. Larger tanks of 75 gallons and up concentrate a lot of weight, so place them over floor joists, ideally perpendicular to them, and consult a professional if you are unsure. A 180 gallon system can exceed a ton fully set up.
Does substrate add much weight?
Yes. Sand and gravel are dense, adding roughly 85 to 105 pounds per cubic foot. A few inches across a large footprint can add a hundred pounds or more. Use our substrate calculator to estimate it, then add it in the field above.
