Aquarium weight calculator
Add up water, glass, wet substrate, rock and the stand to see what a set-up tank really weighs — and how hard it presses on your floor.
How the weight is calculated
A set-up aquarium weighs much more than its water. This calculator adds five parts:
- Water — the real water volume (inside the glass, below the water line and above the substrate) × 8.34 lb per gallon for fresh water or 8.55 lb for saltwater at a specific gravity of 1.025.
- Empty tank — the area of the bottom and four walls × glass thickness × the density of glass (2.5 kg per liter), plus 10% for the frame, silicone and braces. Acrylic is about half as dense as glass.
- Substrate — weighed wet: dry gravel or sand plus the water held between the grains, roughly 35% of the bed's volume.
- Rock, decor, stand and equipment — whatever you enter. Live rock in a reef is often 1–1.5 lb per gallon; a wooden cabinet stand is typically 40–120 lb.
Floor load
The floor load is the total weight divided by the stand's footprint, in pounds per square foot. US homes are typically designed for a live load of about 40 lb/ft² averaged over a room, but an aquarium is a concentrated load: a set-up 55-gallon tank on a 48 × 13 inch stand presses down at well over 100 lb/ft². Floors handle this when the stand spans several joists and sits close to a load-bearing wall. For tanks over about 125 gallons, upstairs rooms or older houses, ask a structural engineer or contractor.
Typical weights
As a rule of thumb, a freshwater tank with gravel weighs about 10 lb per gallon once set up. See the tank size chart for every standard size, or read how much does a fish tank weigh for a detailed breakdown.
FAQ
How much does a 55-gallon fish tank weigh?
About 80 lb empty and roughly 545 lb set up with water filled to an inch below the rim and 2 inches of gravel, before rock, decor and the stand.
How much does water weigh per gallon?
Fresh water weighs 8.34 lb per US gallon. Saltwater at specific gravity 1.025 weighs about 8.55 lb per gallon.
Can my floor hold a fish tank?
Most modern floors handle tanks up to about 55–75 gallons when placed across the joists near a load-bearing wall. Larger tanks, upstairs rooms and older homes deserve a professional check.