Volume Calculator
Choose a shape, enter the dimensions, and get the volume in cubic metres, litres, US gallons and cubic feet at once. Select an estimated fill density or enter your supplier’s density, then set the bag weight to turn that volume into a material order.
Your measurements
Check your order
Your fill-material order
- Confirm the fill shape and specified depth. Check any settlement or compaction allowance separately; this calculator does not add it.
- Use the supplier’s density for a weight estimate; the preset densities are approximate.
- Match the quantity to the actual bag weight or delivery unit. Confirm any extra allowance with the supplier before rounding the final order.
Tools for this job
Measure length, width and depth separately before calculating volume. A longer tape is useful for outdoor footprints, while a short tape checks depth.
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- Check room dimensions and cuts
Short tape measure
STANLEY 25-foot tape measure
For checking lengths, widths and short runs before ordering. This is a 25-foot tape; use matching units in the calculator and check the scale on the selected model.
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Long tape measure
Komelon 6611 100-foot open-reel tape
For measuring longer outdoor runs and marking out areas. Keep the tape straight and use the same units throughout; this listing is for the 100-foot model.
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Volume formulas
Volume units and how they relate
| Unit | Value of 1 m³ | Notes |
|---|---|---|
| Litres | 1,000 | 1 litre is exactly one cubic decimetre |
| US gallons | 264.17 | Used for US tank and pool capacity |
| Imperial gallons | 219.97 | UK, about 20% larger than a US gallon |
| Cubic feet | 35.31 | Common for shipping and loft volume |
| Cubic yards | 1.308 | How ready-mix concrete and topsoil are sold in the US |
| Kilograms of water | 1,000 | Water is the reference: 1 litre = 1 kg |
Worked example: a garden bed
A raised bed 2 m long, 1 m wide and 0.5 m deep. V = 2 × 1 × 0.5 = 1 m³, which is 1,000 litres or 35.3 cubic feet.
Using the illustrative topsoil density of 1,500 kg/m³ gives 1.5 tonnes. If that supplier sells 800 kg bags, round 1,500 ÷ 800 up to two bags. These are explicit assumptions: check the actual product’s density, bag volume and settlement guidance before ordering.
Worked example: a cylindrical tank
A water butt 0.6 m in diameter and 1.2 m tall. Radius = 0.3 m. V = π × 0.3² × 1.2 = 0.339 m³ = 339 litres, or 90 US gallons.
Using the water estimate of 1,000 kg/m³ gives about 339 kg, plus the empty tank. Check the tank manufacturer’s support and installation requirements for that full load.
Estimating a partly filled tank
- Vertical cylinder or box: the volume is proportional to the depth. Half full is half the volume. Just enter the fill depth instead of the full height.
- Horizontal cylinder: it is not proportional, because the cross-section is a circular segment. Half full is exactly half, but a quarter of the depth is only about 19% of the volume.
- Sphere: a partly filled sphere follows V = π h² (3r − h) ÷ 3, where h is the fill depth.
Loose material: volume versus weight
Aggregates are ordered by weight but used by volume, and the bridge between them is the bulk density, which is not the density of the rock but of the rock plus the air between the pieces. Damp sand is around 1,600 kg/m³, gravel about 1,500, and compacted MOT type 1 around 2,100.
Select a density preset for an estimate, or choose Custom and enter the supplier’s density in kg/m³. Set the weight per bag from the listing; the starting value of 800 kg is only an example. Bags are rounded up from volume × density ÷ bag weight. No settlement or waste allowance is added.
Match the density to the material state: a loose delivery density and a compacted in-place density are not interchangeable. For compost and bark sold in litres, leave the fill selector on volume only and divide the required volume by the supplier’s pack volume.
Sources and assumptions
The selected geometric solid determines volume. A capsule is a straight cylinder plus two hemispheres; a hollow pipe subtracts the inner cylinder from the outer cylinder. Fill mass is volume multiplied by a selected density estimate or an entered supplier density. Bag counts divide that mass by the entered bag weight and round up to whole bags.
- NIST: SI units of volume: NIST confirms that a litre is one cubic decimetre and one cubic metre is 1,000 litres.
- Rolawn: calculating topsoil requirements: The producer explains area × depth and notes that topsoil bulk density varies by composition; weight conversions need the product specification.
Before using this estimate
- Use internal tank measurements for capacity. The shape calculation assumes a fully filled solid, except when entering a fill depth for a vertical box or cylinder. No settlement, compaction or waste allowance is added automatically.
- Preset bulk densities and the initial 800 kg bag are planning examples. Enter the supplier density and actual bag weight where available, matching density to the loose or compacted state of the measured material. Moisture and grading affect density; water at 1,000 kg/m³ is an approximation.
Source notes reviewed . See how we check calculations and handle corrections.
Planning your order
Check the inputs before buying: measure the surfaces you need, then apply an allowance and round to whole packs. The guides include worked examples you can follow alongside this calculator.
Published by OrderEnough. This is a planning estimate: check the product specification and the assumptions above before ordering. Last updated . Read how we source our figures on the methodology page.