You are estimating an aquarium, water tank, planter, bucket, bin, or other simple container before filling or buying material.
Tank and Container Volume Calculator
Estimate rectangular, cylindrical, or tapered tank capacity, fill volume, water weight, and soil-bag equivalents in metric or US customary units.
Start here
Choose rectangular, cylindrical, or tapered shape and select a dimension unit.
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Your dimensions and volume estimates are calculated locally in your browser and are not uploaded to a server.
Useful for
Estimate aquarium or water-tank capacity
Estimated filled volume15.71 US galAfter fill-level adjustment
Liters59.47 L
Cubic feet2.1 ft³
Imperial gallons13.08 Imp gal
Water weighs about 131.1 lb (59.47 kg)
Water only; add the tank, substrate, rock, equipment, and stand separately.
Calculation
length × width × height, multiplied by a 90% fill level and 1 container(s).
Quick answer
Estimate tank or container capacity from its dimensions
Choose a rectangular, cylindrical, or tapered shape, enter dimensions and fill level, and convert the result to liters, gallons, or cubic units.
Real usable capacity may be lower because of wall thickness, rounded corners, fittings, freeboard, displacement, or an irregular interior shape.
Unit Converter: Convert common length, weight, area, and volume units for everyday measurements, recipes, room size, packages, and metric-imperial checks.
About this tool
Estimate rectangular, cylindrical, or tapered tank capacity, fill volume, water weight, and soil-bag equivalents in metric or US customary units.
Your dimensions and volume estimates are calculated locally in your browser and are not uploaded to a server.
Reminder
Use inside dimensions for usable capacity. Rounded corners, wall thickness, taper, displacement, freeboard, and irregular shapes can reduce real volume. Water weight is an approximation and does not confirm structural safety.
How to use it
- Choose rectangular, cylindrical, or tapered shape and select a dimension unit.
- Enter the inside dimensions, fill percentage, and number of containers.
- Review capacity, filled volume, water-weight estimate, and optional soil-bag equivalents.
Common use cases
- Estimate aquarium or water-tank capacity
- Calculate a planter or raised-container volume
- Estimate liquid at a partial fill level
- Convert dimensions to liters, US gallons, cubic feet, or cubic meters
Volume Formulas by Container Shape
Measure inside dimensions when you need usable capacity. The tool converts the selected input unit to a common internal volume, then reports several familiar output units.
| Shape | Formula | Input reminder |
|---|---|---|
| Rectangular | length × width × height | Use inside length, width, and filled height |
| Cylinder | π × radius² × height | Enter inside diameter; radius is half |
| Tapered rectangular | frustum formula | Measure both top and bottom inside dimensions |
Capacity, Fill Level, and Water Weight
A fill percentage scales the geometric capacity. A 50 US gal tank at 80% contains an estimated 40 US gal. Water weight is only an approximation and changes slightly with temperature and dissolved material.
- Leave freeboard where splashing, expansion, or overflow is possible.
- Subtract rocks, pumps, soil, plants, or other displaced volume when precision matters.
- Ask a qualified professional to verify stands, floors, walls, and other load-bearing structures.
FAQ
Should I enter inside or outside dimensions?
Use inside dimensions when estimating usable capacity. Outside dimensions can overstate volume because they include wall thickness.
How do I calculate a cylindrical tank?
Volume equals pi times radius squared times length or height. Enter diameter rather than radius when the field requests diameter.
Does the calculator support gallons?
Yes. Results include US gallons along with liters and cubic units. Input dimensions can use inches, feet, centimeters, or meters.
Is the water-weight result a load rating?
No. It is an approximate mass or weight conversion and does not verify that a floor, shelf, stand, or container is structurally safe.