Rebar Weight Calculator
This calculator computes the mass of reinforcing steel (rebar) using the geometric cross-section and material density. It returns weight per metre, weight for a single bar (given its length), and total mass for a specified count of bars.
Calculations use SI units: diameter in millimetres, length in metres, and density in kilograms per cubic metre. The default density (7850 kg/m³) is the commonly used nominal value for carbon steel; adjust if you are using stainless or FRP rebar.
Inputs
Results
Weight per metre
15,700
Weight per bar (single length)
94,200
Total weight (all bars)
94,200
Total weight (tonnes)
94.2
| Output | Value | Unit |
|---|---|---|
| Weight per metre | 15,700 | kg/m |
| Weight per bar (single length) | 94,200 | kg |
| Total weight (all bars) | 94,200 | kg |
| Total weight (tonnes) | 94.2 | t |
Visualization
Methodology
We compute cross-sectional area from the nominal diameter using the circle area formula, then multiply by length and material density to obtain mass. This follows standard material-property methods used in structural engineering and materials science.
Default material density is set to 7850 kg/m³. If you have manufacturer data or a materials standard for a specific grade, replace the density value to reflect that specification.
For field use, measure length with calibrated tape measures and confirm diameter against manufacturer labels or inspection gauges. Small measurement errors in diameter propagate quadratically into mass, so diameter accuracy is especially important.
Expert Q&A
Why does diameter accuracy matter more than length accuracy?
Cross-sectional area depends on the square of diameter. A 1% error in diameter produces roughly a 2% error in area and thus mass, whereas a 1% error in length produces a 1% error in mass.
What density value should I use for different rebars?
7850 kg/m³ is the standard nominal density for most carbon steels. Use manufacturer or material-certification data for stainless, epoxy-coated, or FRP bars. If uncertain, consult material test reports or standards from recognized bodies.
Can I enter lengths in feet?
This calculator expects length in metres. Convert feet to metres by multiplying by 0.3048. Guidance and conversion links are provided in the citations below.
How accurate are the results for procurement and shipping?
This tool provides engineering-level estimates adequate for takeoffs and early procurement. Final ordering and shipping weights should use manufacturer-supplied weights, mill certificates, or weighbridge measurements to account for tolerances, coatings, and bundling.
Do coatings or ribbing affect the calculated weight?
Light coatings (e.g., epoxy) add small additional mass; heavy galvanizing or coatings may be significant. Ribbing geometry is already included in nominal diameter where the listed diameter is an equivalent (manufacturers often provide actual mass per metre). For highest accuracy, use manufacturer mass-per-length data.
How should I verify the tool on-site?
Compare calculator outputs with known samples: measure diameter with calipers, measure length, then weigh a single known-length sample on a calibrated scale. Differences larger than expected manufacturing tolerances should prompt a review of inputs or the use of mill-certified weights.
Sources & citations
- NIST - Reference Materials and Data — https://www.nist.gov/srd
- MIT OpenCourseWare - Materials Science resources — https://ocw.mit.edu
- U.S. Occupational Safety and Health Administration (OSHA) - Handling and storage of construction materials — https://www.osha.gov
- International Organization for Standardization (ISO) - standards and technical guidance — https://www.iso.org