TOOL 10
Aquarium Weight
Calculator.
A filled tank is far heavier than most people expect. Add up water, substrate, glass and decor so you know what your floor and stand really have to carry.
Water ≈ 1 kg per litre. Glass ≈ 2.5 kg per cm³ (density 2.5 g/cm³). Substrate weight uses density × volume — gravel and sand typically run 1.4–1.7 kg/L, aquasoil around 0.9–1.1 kg/L.
ABOUT THIS TOOL
Aquarium Weight
Calculator.
An aquarium is a heavy, static load, and underestimating it is one of the most common and most dangerous mistakes in the hobby. A modest 120 cm tank can weigh well over 250 kilograms once water, substrate, glass and hardscape are counted. Repeatedly putting that load on a piece of furniture that was never designed for it is a recipe for a sudden, catastrophic failure.
This calculator adds the major components — water, substrate, glass and decor — into a realistic total. Water is estimated at roughly one kilogram per litre, adjusted for the space the substrate occupies and a small rim allowance. Glass weight is estimated from the tank dimensions and a thickness chosen to fit the tank height, since taller tanks use thicker, heavier panels.
Use the result to check that your stand is rated for the load, that the floor can take the concentrated weight, and that you have a safety margin. As a rule, choose a stand rated comfortably above the calculated figure — never right at the edge — and place large tanks across floor joists rather than between them.
HOW TO USE
Using the
Calculator.
- Enter tank dimensionsMeasure the external length, width and height of the tank in centimetres. Height should be the glass height, not including a hood or rim.
- Set the substrate depthEstimate the average depth of your substrate in centimetres. A typical planted tank runs 3–6 cm.
- Choose the substrate densityPick gravel, sand, or aquasoil. If you know your material, enter its density directly for a closer estimate.
- Add your decor weightWeigh or estimate the total weight of rocks and driftwood in kilograms. Large stones can be surprisingly heavy.
- Read the total weightThe primary result is the estimated filled weight in kilograms, with pounds shown alongside for reference.
- Check your stand ratingCompare the total with your stand and floor capacity. Choose a safety margin and, for large tanks, place across joists.
FAQ
Weight
Questions.
How much does a 100 litre tank weigh filled?
A 100 litre tank typically weighs around 110–130 kg filled once substrate, glass and decor are included — often more than people assume. Larger tanks scale faster than intuition suggests because glass gets thicker as tanks get bigger.
Can my furniture hold an aquarium?
Most household furniture is not rated for aquarium loads and will deform or collapse. Use a stand specifically built or rated for the tank volume, and never a shelf, cabinet or table designed for general storage.
Should I place the tank across floor joists?
For larger tanks, yes. Setting the tank perpendicular to the joists (across them) spreads the load over more structure. Placing a heavy tank between joists can bow the floor over time. On a concrete slab, placement is much less of a concern.
How accurate is the glass weight estimate?
It is a reasonable approximation based on typical glass thickness for the tank height. Rimless tanks, bracing, and thicker custom glass will shift the figure. For critical load planning, weigh your actual tank if possible.
Does substrate really matter that much?
Yes. A deep gravel bed in a large tank can add 50–100 kg. Using a lighter aquasoil instead of dense gravel can meaningfully reduce the total, and aquasoil is often better for plants anyway.
What safety margin should I leave?
Choose a stand and floor arrangement rated well above the calculated weight — a 50% overhead is a sensible target. Safety margins absorb dynamic loads from water changes, accidental bumps, and imperfect leveling.