Every component counts
Include the empty aquarium, dry substrate, rocks, equipment and cabinet instead of treating water weight as the total.
Tools
Aquarium weight calculator
Estimate the weight of your filled fish tank, from the water and glass to the substrate, rocks and stand. See the whole setup in kilograms and pounds.
Estimated setup weight
Calculate to see total kilograms and pounds, plus a breakdown of everything you included.
Total = water + empty tank + dry substrate + decorations + equipment + stand. A zero weight excludes that item. Do not count water again in wet substrate or filled equipment.
This estimates mass only. It does not certify a stand or floor: support layout, construction and load distribution need a separate assessment. Saltwater density is an approximation, not a temperature or salinity measurement.
Kilograms and pounds
Convert inputs without changing the physical amount. Results show both kg and lb, with separate US and UK gallon inputs.
Actual water volume
Account for the space taken by solid materials and the gap above the waterline before entering liters or gallons.
Fish tank weight chart
How much does a full aquarium weigh?
Water is only part of the load. Two tanks with the same gallon rating can have different glass, frames, rockwork and stands. Use actual water volume and your own component weights for the total.
Water weight for popular aquarium sizes
Freshwater only at approximately 1 kg/L, using nominal US gallons. These are not filled-system weights or manufacturer tank specifications. Add the empty tank and all other components, and reduce water volume for displacement.
| Nominal size (US gal) | Water (L) | Water weight (kg) | Water weight (lb) |
|---|---|---|---|
| 10 | 37.9 | 37.9 | 83.5 |
| 20 | 75.7 | 75.7 | 166.9 |
| 29 | 109.8 | 109.8 | 242.0 |
| 40 | 151.4 | 151.4 | 333.8 |
| 55 | 208.2 | 208.2 | 459.0 |
| 75 | 283.9 | 283.9 | 625.9 |
| 125 | 473.2 | 473.2 | 1043.2 |
The aquarium weight formula
Water weight in kg = actual water volume in liters × water density in kg/L. Add the empty tank, dry substrate, decorations, equipment and stand. Freshwater is approximated as 1 kg/L; saltwater as 1.025 kg/L. Temperature and salinity affect real density.
One US gallon is 3.785411784 L, one UK gallon is 4.54609 L, and one pound is 0.45359237 kg. The calculator converts units before adding weights. It does not infer the empty tank weight from its gallon rating.
Worked example: a 100 L aquarium
With 100 L of actual freshwater, a 20 kg empty tank, 10 kg of dry substrate, 5 kg of rocks and 5 kg of equipment, the estimate is 140 kg (308.65 lb), excluding the stand. A 25 kg cabinet would bring that setup to 165 kg (363.76 lb).
The example component weights are illustrative. Use the manufacturer’s empty-tank specification or a measured weight. Include sump water in actual water volume and the empty sump in component weights when calculating a complete system.
How much does a 55 or 75 gallon fish tank weigh?
55 US gallons of freshwater alone weigh about 208.2 kg (459 lb); 75 US gallons weigh about 283.9 kg (625.9 lb). The filled aquarium also contains the tank itself and any substrate, rocks and equipment. There is no single universal total for either size.
A 10 gallon water fill adds approximately 37.9 kg (83.5 lb), while 20 gallons adds 75.7 kg (166.9 lb). Nominal capacity is a starting point: decorations and unfilled headspace usually reduce actual water volume.
Avoid counting displaced water twice
Use the water actually held after allowing for substrate, rocks and headspace. Then add dry solid weights separately. Do not add a full nominal tank of water and wet substrate as if neither displaced water.
The result is not a floor-load or stand-safety verdict. Joist spans, support positions, cabinet feet and construction affect how the load is carried. Consult the tank and stand manufacturer, or a qualified structural professional where needed.
FAQ
Aquarium Weight Calculator FAQ
Does the calculator include the stand?
Only if you enter its weight. The example starts at zero for the stand. Add the cabinet and stored supplies if they contribute to the load you want to estimate.
Can I use this for a glass or acrylic tank?
Yes. Enter the actual empty weight of either tank. The calculator does not assume a material density or recommend panel thickness.
Why are US and UK gallons different?
A US gallon is 3.785411784 liters and a UK imperial gallon is 4.54609 liters. Select the convention used by your tank or measuring container.
Will this tell me whether my floor can support the aquarium?
No. It estimates mass, not structural capacity. The same mass can create different loads depending on the stand and building structure.
Related aquarium planning
Continue with the next aquarium decision.
Use the calculator result with logs, guides, and maintenance tools so one number becomes part of a repeatable aquarium care routine.