Rebar Weight Calculator
Calculate the total weight of reinforcement bars (rebar) by size, length, and quantity.
Supports metric and imperial bar sizes.
Total Rebar Weight
Rebar (reinforcing bar) weight is calculated from the bar’s diameter and length. Knowing the weight lets you estimate material costs, transportation loads, and structural reinforcement capacity.
The Formula:
Weight (kg) = (Diameter in mm)^2 / 162 × Length (m)
This is derived from: Weight = Volume × Density where steel density = 7,850 kg/m³
Simplified: Weight per meter by bar size:
| Bar Designation | Diameter (mm) | kg per meter |
|---|---|---|
| R6 | 6 mm | 0.222 kg/m |
| R8 | 8 mm | 0.395 kg/m |
| N10 | 10 mm | 0.617 kg/m |
| N12 | 12 mm | 0.888 kg/m |
| N16 | 16 mm | 1.578 kg/m |
| N20 | 20 mm | 2.466 kg/m |
| N24 | 24 mm | 3.551 kg/m |
| N32 | 32 mm | 6.313 kg/m |
Worked Example:
A slab reinforcement requires:
- 50 bars of N12 rebar, each 6 meters long
Weight per bar = 0.888 × 6 = 5.328 kg Total weight = 50 × 5.328 = 266.4 kg
At $1.50/kg steel price: Material cost = $399.60
Practical Tips:
- Add 5–10% wastage for lapping, bending, and cutting losses
- Minimum lap length = 40 × bar diameter (e.g., N12 bars need 480 mm laps)
- Bar spacing in slabs is typically 150–300 mm center-to-center depending on loading
- Always verify rebar specifications with structural engineer drawings — never guess