How Much Does a Fish Tank Weigh, and Can Your Floor Take It? A 60 cm Tank Is About 73 kg, a 90 cm Tank Over 200 kg
Once filled with water, an aquarium is heavier than most people expect. Even a standard 60 cm tank passes 70 kg once you add water, substrate and glass, and a standard 90 cm tank passes 200 kg. This guide breaks down tank weight by size, explains how to compare it with Japan’s residential floor live-load standard (about 180 kg per m²), and covers what to watch for on an upper floor or in a rental, plus preparing for earthquakes and leaks.
A tank’s weight is mostly water + substrate + glass
One litre of water weighs almost exactly 1 kg, so the volume of water is its weight. Add the substrate and the glass on top. Glass weighs about 2.5 kg per m² for every 1 mm of thickness, so in a large tank with thick panes the glass alone can be tens of kilograms.
Take a standard 60 cm tank (60 × 30 × 36 cm, 5 mm glass) with 4 cm of Oiso gravel and the water 3 cm below the rim: the water is about 51.5 kg, the substrate about 11.0 kg and the glass about 10.4 kg, for a total of about 72.8 kg. On top of that come the stand, an external filter, lights, rocks and driftwood.
Weight by tank size
These weights assume 4 cm of Oiso gravel and the water 3 cm below the rim. The stand, equipment and rocks are not included. “Per m² of footprint” is the total weight divided by the area of the tank’s base (outer dimensions). Sizes are standard Japanese tank sizes.
| Size | Water | Substrate | Glass | Total | Per m² of footprint |
|---|---|---|---|---|---|
| 30 cm standard | 9.6 kg | 3.4 kg | 2.9 kg | 15.9 kg | about 281 kg |
| 30 cm cube | 20.3 kg | 5.4 kg | 5.6 kg | 31.3 kg | about 348 kg |
| 45 cm standard | 24.4 kg | 6.5 kg | 6.5 kg | 37.4 kg | about 346 kg |
| 45 cm cube | 74.8 kg | 12.3 kg | 15.2 kg | 102.3 kg | about 505 kg |
| 60 cm standard | 51.5 kg | 11.0 kg | 10.4 kg | 72.8 kg | about 404 kg |
| 60 cm wide | 100.4 kg | 16.5 kg | 18.2 kg | 135.1 kg | about 501 kg |
| 90 cm standard | 148.9 kg | 24.6 kg | 32.4 kg | 205.8 kg | about 508 kg |
| 120 cm standard | 195.9 kg | 32.5 kg | 50.6 kg | 279.0 kg | about 517 kg |
Even among “60 cm” tanks, the wide type with 45 cm depth and height weighs nearly twice as much as the standard size. Cube tanks and tall tanks are heavy for their small footprint, so their weight per m² is high.
Comparing with the floor live-load standard of “about 180 kg per m²”
In Japan, Article 85 of the Order for Enforcement of the Building Standards Act sets the live load for structural calculations of residential living-room floors at 1,800 N per m² (about 180 kg). Floors are built with a safety margin on top of this, so it doesn’t mean the floor fails as soon as you exceed 180 kg. But the standard assumes the weight is spread across the whole room.
An aquarium concentrates its weight on a small area. The base of a standard 60 cm tank is only 0.18 m², yet about 73 kg sits on it, or around 90 kg with the stand and equipment. Per m² that is more than twice the standard, but only those 0.18 m² of the room are loaded, which is why tanks up to the 60 cm standard are commonly kept on ordinary residential floors. The ones to be careful with are tanks of 90 cm and up, whose total weight alone exceeds 180 kg.
| Approximate total weight | Example sizes | How to think about it |
|---|---|---|
| 40 kg or less | Up to 45 cm standard | On sturdy furniture or a tank stand, the floor is hardly a concern |
| 70–140 kg | 60 cm standard, 45 cm cube, 60 cm wide | Use a dedicated aquarium stand and place it by a wall |
| Over 180 kg | 90 cm and 120 cm standard | Check the floor structure; if unsure, ask the builder or property manager |
- 1
Place it against a wall
Floors deflect less near walls and columns. Avoid the middle of the room.
- 2
Set it at right angles to the joists
Placing the tank so its long side crosses the floor joists at right angles lets several joists share the load. The direction of the floorboard seams is a good clue.
- 3
Spread the load with a board
If the stand has thin legs, put a thick board underneath to increase the area touching the floor.
Upper floors, rentals, earthquakes and leaks
- Some rental contracts forbid large aquariums. If you’re going over 60 cm, check with the property manager first
- On an upper floor, a leak is a bigger risk than floor deflection. Water reaching the flat below makes repairs expensive
- Check whether you have personal liability insurance (often an add-on to home or car insurance)
- Use a stand made for the size of your tank. Cube shelving and ordinary furniture may not hold the weight over the long term
- For earthquakes, put an anti-vibration mat under the tank and keep the water level a little lower so less spills when it shakes
Never move a tank with water in it. Even a standard 60 cm tank is over 70 kg, and lifting it puts stress on the glass seams that can cause cracks or leaks. To move it for cleaning or rearranging, transfer the fish to another container and drain the water first. Once a stand has water on it, even a slight tilt is hard to fix, so check it with a spirit level before you set up.
The easiest way to worry less about the floor is not to choose a bigger tank than you need. You can work back from the number of fish to the water you need in the real water volume of an aquarium, and see how weight changes with less substrate in calculating substrate amounts.
FAQ
- How much does a 60 cm fish tank weigh?
- A standard 60 cm tank (60 × 30 × 36 cm) with 4 cm of Oiso gravel and filled with water is about 51.5 kg of water, 11.0 kg of substrate and 10.4 kg of glass, about 73 kg in total. With the stand and equipment it is around 90 kg.
- Is it safe to put a 90 cm tank upstairs?
- A standard 90 cm tank with 4 cm of gravel is about 206 kg, exceeding the residential floor live-load standard (about 180 kg per m²) over a much smaller area. Place it against a wall and across the joists, and it is safest to consult the builder or property manager.
- What does a floor load of 180 kg mean?
- It is the live load (1,800 N per m²) that Japan’s Building Standards Act enforcement order specifies for designing residential living-room floors. It assumes the weight is spread over the whole room, and real floors have a safety margin.
- How do you calculate the weight of a fish tank?
- Add water at about 1 kg per litre, substrate at about 1.6 kg per litre for Oiso gravel, and glass at about 2.5 kg per m² per 1 mm of thickness. Use the water volume inside the glass up to the water line, not the outer dimensions.
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