Cubic Feet to Pounds Calculator
Cubic feet and pounds measure different things, volume and weight, so converting between them needs a third figure: the material's density. This calculator does that conversion for you. Enter a volume in cubic feet, then choose a material from the preset list, water, concrete, dry or wet sand, loose or packed soil, dry or wet gravel, steel, aluminium, pine or oak timber, brick, or asphalt, or type in a custom density in pounds per cubic foot if your material is not listed. The calculator multiplies your volume by the density to return the weight in pounds, plus the equivalent in kilograms, metric tonnes and US short tons. A breakdown panel also shows the figure in ounces and grams, plus a table listing how much 5, 10 and 27 cubic feet (one cubic yard) of each preset material would weigh, so you can compare options at a glance. It is useful for builders checking whether a floor or trailer can carry a pile of gravel or bags of concrete, truckers watching load limits, aquarium owners weighing a tank before it goes on a shelf, and landscapers estimating how much soil a ute can carry. Because real-world densities vary with moisture, compaction and grade, treat the results as a close estimate, and check supplier data for anything load-bearing or safety-critical.
1. Volume
2. Material / Density
Conversion Breakdown
Weight in All Units
Weight per Cubic Foot by Material
| Material | Density (lb/ft³) | 5 ft³ weighs | 10 ft³ weighs | 1 yd³ (27 ft³) weighs |
|---|
How to Convert Cubic Feet to Pounds
Volume (cubic feet) measures the amount of space a material occupies. Weight (pounds) measures the force of gravity acting on the material's mass. To convert between the two, you need the material's density, which tells you how many pounds fit in one cubic foot.
The formula is straightforward:
Weight (lb) = Volume (ft³) × Density (lb/ft³)
For example, if you have 5 cubic feet of water and water weighs 62.43 lb/ft³:
Weight = 5 × 62.43 = 312.15 lb
This is why you cannot convert cubic feet to pounds without specifying the material. Five cubic feet of steel weighs about 2,450 lb, while five cubic feet of pine timber weighs only about 155 lb.
Common Material Densities in lb/ft³
| Material | Density (lb/ft³) | Density (kg/m³) | Notes |
|---|---|---|---|
| Water | 62.43 | 1,000 | Standard at 4°C |
| Concrete, normal weight | 150 | 2,400 | Ready-mix, cured |
| Sand, dry | 100 | 1,600 | Loosely packed |
| Sand, wet | 110 | 1,760 | Saturated |
| Soil, loose dry | 75 | 1,200 | Varies significantly |
| Soil, packed | 95 | 1,520 | Compacted fill |
| Gravel, dry | 100 | 1,600 | Mixed aggregate |
| Gravel, wet | 120 | 1,920 | Saturated aggregate |
| Steel | 490 | 7,849 | Structural steel |
| Aluminium | 168 | 2,700 | Pure aluminium |
| Pine timber | 31 | 497 | Dry radiata pine |
| Oak timber | 45 | 721 | Dry hardwood |
| Brick | 94 | 1,506 | Standard clay brick |
| Asphalt | 87 | 1,395 | Compacted road mix |
Converting Between Cubic Feet and Cubic Yards
One cubic yard equals 27 cubic feet (3 ft × 3 ft × 3 ft). If your volume is quoted in cubic yards, multiply by 27 before applying the density. For example, one cubic yard of concrete (27 ft³ × 150 lb/ft³) weighs 4,050 lb (about 2 short tons), which is why concrete delivery trucks are rated by the cubic yard.
Converting Pounds to Kilograms and Tonnes
Once you have the weight in pounds, you can convert to metric units:
- Kilograms: divide by 2.20462 (or multiply by 0.453592)
- Metric tonnes: divide by 2,204.62
- Short tons (US): divide by 2,000
- Long tons (UK): divide by 2,240
For example, 312.15 lb of water converts to 141.59 kg, or 0.14 metric tonnes.
Practical Uses
Knowing the weight of a volume of material is useful in many real-world situations. Builders need to know whether a floor or trailer can handle the load from a pile of gravel or bags of concrete. Truckers need to stay within load limits. Aquarium owners calculate the weight of water before placing a tank on a shelf. Landscapers estimate how many cubic metres of soil a ute can carry before exceeding its payload. This calculator handles all of these scenarios by letting you choose the right material density.
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Method: Weight (lb) = Volume (ft³) × Density (lb/ft³). Density values are standard engineering reference figures from ASTM, ACI 318, and the Engineering Toolbox. Material densities vary depending on moisture content, compaction, and grade; the values shown are typical averages.
Material densities are approximate averages. Actual weight depends on moisture content, compaction, grade, and temperature. For structural or load-bearing calculations, consult a qualified engineer and verify material specifications with your supplier.