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The total water volume of the aquarium tank.
Use the tank's rated water volume from the manufacturer's spec sheet, or calculate it as length x width x height for a rectangular tank.
Total water weight
1,080 lb
This calculates water weight only (add the tank/stand/substrate/rock weight separately for a full load total) — it does NOT verify structural adequacy of the supporting floor, stand, or wall, which must be confirmed by a qualified structural engineer for any large or built-in aquarium installation. Saltwater is about 2.5% denser than fresh water.
They open the calculator with your figures already in it
Aquarium Display Tank Water Weight Calculator: 1,085 lb — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Water weight (kg) = Tank Volume (L) × 1.0 kg/L (fresh water density ≈ 1.0 kg/L at typical aquarium temperatures; saltwater is slightly denser, ≈1.025 kg/L). This is a load QUANTITY calculation only — actual structural adequacy of the supporting stand, floor, or wall must be verified by a qualified structural engineer, especially for large built-in or wall-mounted aquariums.
Inputs used
- Aquarium Tank Volume
- 130 gal
Confidence note: This calculates water weight only (add the tank/stand/substrate/rock weight separately for a full load total) — it does NOT verify structural adequacy of the supporting floor, stand, or wall, which must be confirmed by a qualified structural engineer for any large or built-in aquarium installation. Saltwater is about 2.5% denser than fresh water.
What this calculation does not cover
- A total weight is not what a floor feels. What matters is that weight over the stand's actual footprint and how that footprint sits relative to the joists below. 500 kg (1,102 lb) on a 1.2 by 0.4 m (1.3 ft) stand is over 1,000 kg (2,205 lb) per square meter concentrated on a strip — several times the uniform live load a residential floor is designed for — and a stand running parallel between two joists loads them very differently from one set across four. This figure is the input to that check, not the check.
- The rated volume is not the water volume, and correcting it does not lighten the tank. Tanks fill below the rim, and substrate, rock and hardscape displace water — but every one of those materials is denser than the water it pushes out, so swapping 40 liters (10.5 gal) of water for 40 liters (10.5 gal) of saturated live rock makes the installation heavier, not lighter. Take rock and sand from their own wet weights rather than assuming the displaced water cancels them.
- A marine system holds water in more places than the display. Sump, refugium, plumbing and an auto-topoff reservoir commonly add 20 to 30 percent more volume, and almost all of it sits in the cabinet directly under the tank — on the same square meter of floor already carrying the display. A freshwater canister setup adds less, but it is not nothing.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Water weight (kg) = Tank Volume (L) × 1.0 kg/L (fresh water density ≈ 1.0 kg/L at typical aquarium temperatures; saltwater is slightly denser, ≈1.025 kg/L). This is a load QUANTITY calculation only — actual structural adequacy of the supporting stand, floor, or wall must be verified by a qualified structural engineer, especially for large built-in or wall-mounted aquariums.
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