Before you hire a truck, size a lifting strap or check a shelf rating, you need the weight of what you are moving. For a solid rectangular object the weight is simply its volume times the density of the material. This tool includes typical densities for building materials, metals, timbers, liquids and bulk fills, and you can type your own density for anything else.
How to use the Size to Weight Calculator
- Material
- Custom density
- Length
- Width
- Height
- Quantity
- Every result field is editable: type into Weight of one box or any other result and Height plus every other field update to match.
Results update as you type, and every field accepts the units shown in its menu.
How it works
Choose a material (or enter a custom density), enter the three dimensions and the quantity. The calculator multiplies the dimensions for the volume and applies the density to get the weight of one piece and of the whole batch.
Tips for an accurate estimate
- Measure every dimension twice and write the unit next to each number – most estimating errors are unit mix-ups (inches entered as feet).
- Pick the unit in each field’s menu instead of converting by hand; the calculator converts everything to the same base before it multiplies.
- Round up only at the very end. Rounding each dimension first can add several percent to the final quantity.
- Suppliers sell in whole units – bags, boxes, sheets or quarter yards – so always round the final order up, not down.
Common mistakes to avoid
- Mixing square and cubic units: square feet measure area, cubic yards measure volume, and you need a depth to go from one to the other.
- Using nominal lumber sizes where actual sizes matter (a 2×4 is really 1½ × 3½ in).
- Forgetting that 1 yd³ = 27 ft³, not 9 ft³ (9 is for square yards).
Inputs explained
| Field | What to enter |
|---|---|
| Material | Choose one: Water, Concrete, Reinforced concrete, Brick … |
| Custom density | Units: kg/m³, lb/ft³, g/cm³, lb/yd³ |
| Length | Units: m, ft, cm, in, yd |
| Width | Units: m, ft, cm, in, yd |
| Height | Units: m, ft, cm, in, yd |
| Quantity | A number |
What each result means
- Volume of one box = [Length]×[Width]×[Height]
- Total weight = [Weight of one box]×[Quantity]
Example values
How the main result changes when Height changes and everything else stays at the example values above:
| Height (m) | Total weight (kg) |
|---|---|
| 0.2 | 100 |
| 0.3 | 150 |
| 0.4 | 200 |
| 0.5 | 250 |
| 0.6 | 300 |
| 0.8 | 400 |
Formula
Volume = length × width × heightWeight = volume × density × quantityWorked example
Inputs — Material: Water; Custom density: 1,000 kg/m³; Length: 1 m; Width: 0.5 m; Height: 0.4 m; Quantity: 1.
Results — Volume of one box = 0.2 m³; Weight of one box = 200 kg; Total weight = 200 kg.
Frequently asked questions
How do I find the weight from size?
Multiply length × width × height to get volume, then multiply by the density of the material. Keep units consistent – for example metres and kg/m³.
Why is my real object lighter?
Hollow parts, voids and moisture all change the weight. Wood can vary by ±20% with species and moisture content.
What is the weight of a cubic metre of water?
1,000 kg (2,205 lb), and a cubic foot of water weighs about 62.4 lb.
What formula does the Size to Weight Calculator use?
Volume = length × width × height.