Weight Conversions Calculator
Convert between metric and imperial weight units. Calculate bag quantities for cement, sand, gravel, and other construction materials. Includes bulk bag sizing and material density conversions.
Weight in Construction
Accurate weight calculations are essential for ordering materials, estimating transport costs, ensuring structural load calculations, and calculating material quantities from volumes.
Standard Bag Sizes
| Material | Standard Size | Coverage/Use |
|---|---|---|
| Cement | 25kg or 50kg | Mortar, concrete, render |
| Plaster | 25kg | ~10m² at 2mm |
| Sand (small) | 25kg | Small jobs, mortar |
| Sand (large) | 40kg | Better value bulk |
| Postcrete | 20kg | ~1 post per bag |
| Mortar Mix | 25kg | ~25 bricks |
Bulk Bag (Ton Bag) Sizes
| Type | Weight | Volume | Best For |
|---|---|---|---|
| Mini Bulk | 250kg | ~0.15m³ | Small projects |
| Standard Bulk | 850kg | ~0.5m³ | General use |
| Jumbo Bulk | 1000kg (1 tonne) | ~0.6m³ | Best value |
| Large Bulk | 1500kg | ~0.9m³ | Large projects |
Material Densities
Convert between volume and weight using material densities:
| Material | Density (kg/m³) | 1m³ weighs |
|---|---|---|
| Cement (dry) | 1,440 | 1.44 tonnes |
| Sand (dry) | 1,600 | 1.6 tonnes |
| Sand (wet) | 1,900 | 1.9 tonnes |
| Gravel | 1,700 | 1.7 tonnes |
| Ballast | 1,750 | 1.75 tonnes |
| Topsoil | 1,200 | 1.2 tonnes |
| Concrete | 2,400 | 2.4 tonnes |
| Steel | 7,850 | 7.85 tonnes |
Weight Conversion Reference
| Metric | Imperial |
|---|---|
| 1 kg | 2.205 lb |
| 1 tonne | 0.984 long tons (UK) |
| 1 tonne | 1.102 short tons (US) |
| 6.35 kg | 1 stone |
| 50.8 kg | 1 cwt (hundredweight) |
Wastage Allowances
Always add wastage when ordering materials by weight:
- Cement: 5-10% wastage
- Sand/Gravel: 5-10% wastage
- Loose materials: 10-15% wastage
- Pre-mixed: 5% wastage
NAIBC / IRC codes
References & Sources
Standards Cited
- NIST Handbook 44 — Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices
Provides authoritative conversion factors between US customary and metric weight units (e.g., 1 lb = 0.453592 kg) View → - ASCE 7-22 — ASCE 7 — Minimum Design Loads and Associated Criteria for Buildings and Other Structures
Source of standard material densities used for volume-to-weight conversions in North American construction
Formulas Used
- Weight Unit Conversion:
result = value x (fromFactor / toFactor)
Source: NIST Handbook 44 — Conversion via kilograms as the intermediate base unit - Bags Required:
bags = ceil(totalWeight x (1 + wastage%) / bagSize)
Source: Construction industry practice — Default 5% wastage allowance - Volume to Weight:
weight (kg) = volume (m³) x density (kg/m³)
Source: ASCE 7 / ACI 318 - Weight to Volume:
volume (m³) = weight (kg) / density (kg/m³)
Source: ASCE 7 / ACI 318
Key Assumptions
- Standard cement bag size of 94 lb (42.6 kg) per US industry standard — Portland Cement Association (PCA)
- Standard bulk bag (super sack) holds 2000 lb (907 kg) or 1 US short ton — Manufacturer industry standard
- Dry sand density of 100 pcf (1600 kg/m³) — ASCE 7 Table C3-1
- Dry cement density of 90 pcf (1440 kg/m³) — Portland Cement Association (PCA)
- Default 5% wastage allowance for bagged materials — Construction industry standard practice
- 1 US short ton = 907.185 kg = 2000 lb — NIST Handbook 44