Rebar Calculator

How the Rebar Calculator works

The rebar calculator computes the total weight and cost of steel reinforcement bars for any structural concrete element. Enter bar diameter, length, and quantity for each bar mark in your schedule — the tool uses the standard weight formula (d²/162 kg/m for Fe500 TMT bars) to give accurate material quantities for procurement and cost estimation.

Bar diameters and weight per metre

Standard IS 1786 TMT bar diameters range from 8 mm to 32 mm. Weight per metre increases with the square of diameter: 8 mm bar weighs 0.395 kg/m, 12 mm bar 0.888 kg/m, 16 mm bar 1.579 kg/m, 20 mm bar 2.469 kg/m, and 25 mm bar 3.858 kg/m. The calculator applies these values automatically when you select the bar diameter from the dropdown.

Spacing rules and cover requirements

For slabs, IS 456 specifies that main reinforcement spacing should not exceed 3× the effective depth or 300 mm, whichever is less. Distribution bars should not exceed 5× the effective depth or 450 mm. Minimum clear cover is 20 mm for slabs, 25 mm for beams, and 40 mm for columns exposed to weather — factors that affect the number of bars that fit within a given section.

Cutting and bending wastage

Bar schedules always include extra length for hooks, bends, and laps. A standard 180° hook adds 9d to bar length, and a 90° bend adds 4d. Lap splice lengths under IS 456 are typically 45–50 times the bar diameter for tension zones. Adding 5% wastage for cutting losses on top of the schedule length is standard practice on Indian construction sites.

Cost estimation and rate variation

Fe500D TMT steel prices in India typically range from ₹58,000 to ₹75,000 per metric tonne depending on brand, region, and market conditions. Entering the current market rate per tonne in the calculator gives you an up-to-date cost estimate. The total weight output also helps you cross-check against contractor quotations and billing to ensure accurate billing.