Aquarium Volume: worked example
| Length (in) | 48 |
|---|---|
| Width (in) | 13 |
| Water height (in) | 20 |
| Volume (US gallons) | 54 |
| Water weight (lb) | 450.6 |
| Volume (liters) | 204.5 |
Aquarium Volume: formula
Enter the inside length, width and water height of the tank in inches. Measure the inside dimensions to the actual waterline, not the full glass height, since water sits below the top rim, and the substrate and decorations reduce it. The calculator divides cubic inches by 231, the number of cubic inches in a US gallon, and also gives liters and the weight of the water at 8.34 pounds per gallon.
Aquarium Volume: changing Length (in)
| Length (in) | Volume (US gallons) | Water weight (lb) | Volume (liters) |
|---|---|---|---|
| 38 | 42.8 | 356.7 | 161.9 |
| 43 | 48.4 | 403.6 | 183.2 |
| 48 (example) | 54 | 450.6 | 204.5 |
| 53 | 59.7 | 497.5 | 225.8 |
| 58 | 65.3 | 544.4 | 247.1 |
Aquarium Volume: compare input ranges
| Input | Tested from | To | Volume (US gallons): low input | Volume (US gallons): high input | Swing |
|---|---|---|---|---|---|
| Length (in) | 43 | 53 | 48.4 | 59.7 | 11.3 (21%) |
| Water height (in) | 18 | 22 | 48.6 | 59.4 | 10.8 (20%) |
| Width (in) | 12 | 14 | 49.9 | 58.2 | 8.3 (15%) |
Aquarium Volume: individual input comparisons
| Input | Value | Volume (US gallons) | Water weight (lb) | Volume (liters) |
|---|---|---|---|---|
| Length (in) | 38 | 42.8 | 356.7 | 161.9 |
| 43 | 48.4 | 403.6 | 183.2 | |
| 48 | 54 | 450.6 | 204.5 | |
| 53 | 59.7 | 497.5 | 225.8 | |
| 58 | 65.3 | 544.4 | 247.1 | |
| Width (in) | 10 | 41.6 | 346.6 | 157.3 |
| 12 | 49.9 | 415.9 | 188.8 | |
| 13 | 54 | 450.6 | 204.5 | |
| 14 | 58.2 | 485.2 | 220.2 | |
| 16 | 66.5 | 554.6 | 251.7 | |
| Water height (in) | 16 | 43.2 | 360.5 | 163.6 |
| 18 | 48.6 | 405.5 | 184.1 | |
| 20 | 54 | 450.6 | 204.5 | |
| 22 | 59.4 | 495.6 | 225 | |
| 24 | 64.8 | 540.7 | 245.4 |
Aquarium Volume: combined input changes
| Length (in) / Width (in) | 10 | 13 | 16 |
|---|---|---|---|
| 38 | 32.9 | 42.8 | 52.6 |
| 43 | 37.2 | 48.4 | 59.6 |
| 48 | 41.6 | 54 | 66.5 |
| 53 | 45.9 | 59.7 | 73.4 |
| 58 | 50.2 | 65.3 | 80.3 |
Aquarium Volume: which assumptions move the result?
Aquarium Volume: values and definitions
| Quantity and definition | Value used |
|---|---|
| Length (in) | 48 |
| Width (in) | 13 |
| Water height (in) — Measure the water level, not the top of the glass. | 20 |
| Volume (US gallons) | 54 |
| Water weight (lb) | 450.6 |
| Volume (liters) | 204.5 |
Aquarium Volume: half and double Length (in)
| Length (in) | Volume (US gallons) |
|---|---|
| 24 | 27 |
| 48 | 54 |
| 96 | 108.1 |
Common error: Trusting the gallon number printed on the box. Glass thickness and the water line change the real volume, and a measured figure is more reliable.
Displacement by sand, rock and decorations means the real water volume is 10% to 20% less than the geometric figure. Rimless tanks and curved glass follow different dimensions. Salt water is slightly heavier than fresh.
Always check that the floor and stand can carry the weight.
Geometry calculators: Annulus Area Calculator, Regular Polygon Calculator, Rhombus Area Calculator, Hemisphere Volume Calculator, Cone Frustum Calculator, Capsule Volume Calculator.
Tank size drives everything you buy for it, from the heater to the filter to the stand. A 48 by 13 by 20 inch tank holds about 54 gallons when filled to the top of that height. Water weighs 8.34 pounds a gallon, so the water alone is over 450 pounds, before the glass, the gravel and the stand.
That weight is why the floor under a large tank matters.
Measure the water height, not the outside height of the glass. A tank filled to two inches below the rim holds noticeably less than its label says.
See the rectangular prism calculator for the same volume math, the cylinder and sphere pages for round tanks and the unit conversion calculators for gallons, liters and pounds. The weight matters for the trades categories, where floor loading is part of planning. The percent and proportion calculators help with dosing.
How many gallons are in a cubic foot?
About 7.48 US gallons, since a cubic foot is 1,728 cubic inches and a gallon is 231.
How much does a filled aquarium weigh?
Water weighs about 8.34 pounds per gallon, so a 54-gallon tank holds about 450 pounds of water, plus the tank, stand and decorations.
Why is my actual water volume less than the calculated volume?
Substrate, rocks and decorations displace water, and the waterline sits below the top of the glass.