About

Estimating steel requirements for reinforced concrete is a daily task for quantity surveyors, site engineers, and procurement managers. The discrepancy between theoretical weight and actual delivered weight can affect budget margins and logistics. This tool calculates the mass of reinforcing bars (rebar) based on standard densities defined by ASTM A615 (Imperial) and ISO 3132 (Metric) standards.

Construction logistics depend heavily on weight limits for cranes and trucks. Knowing the precise weight of a specific length of rebar-or determining how many linear feet/meters correspond to a billed tonnage-prevents overloading and ensures accurate inventory management. This calculator handles standard deformations sizes ranging from light residential mesh support to heavy infrastructure bars.

Formulas

The calculation is based on the nominal density of carbon steel, approximately 7850 kg/m³.

Weight from Length:

W = L × w_unit

Length from Weight:

L = Ww_unit

Where W is Total Weight, L is Total Length, and w_unit is the specific weight per unit length (e.g., kg/m or lb/ft).

Reference Data

Standard Size	Diameter (mm/in)	Weight (kg/m)	Weight (lb/ft)
Metric #6	6 mm	0.222	0.149
Metric #10	10 mm	0.617	0.414
Metric #16	16 mm	1.578	1.060
Metric #25	25 mm	3.853	2.589
Imperial #3	0.375 in	0.560	0.376
Imperial #4	0.500 in	0.994	0.668
Imperial #8	1.000 in	3.973	2.670
Canadian 10M	11.3 mm	0.785	0.527

Frequently Asked Questions

Imperial sizes (ASTM) represent the diameter in eighths of an inch. For example, a #4 bar is 4/8 inch, or 0.5 inches. Metric sizes represent the diameter directly in millimeters (e.g., #10 is 10mm). They are not perfectly interchangeable due to slight variations in cross-sectional area.

No. The tool uses the nominal theoretical weight defined by standards (ASTM A615 / ISO). Actual rebar delivered from the mill may vary by +/- 6% depending on the diameter and source.

Enter the length of a single bar (e.g., 6 meters), calculate the weight, and then manually multiply the result by 100. Alternatively, input the total linear length of all bars combined (6 * 100 = 600m) into the Length field.