Home / Takeoff / Rebar weight K · v1.0

Rebar Weight Take-Off

Bar bending schedule: cut length from outside leg dimensions, bend geometry, hooks and laps — then mass by diameter. Bend radius, hook tail and lap length are code values and must be entered; this tool does not assume them.

Detailing inputs — code values

These four come from the standard in force on your project, not from this tool. The engine refuses to calculate without them rather than substituting a typical value.

Bar schedule

Legs: outside dimensions in mm, comma separated (a straight bar is one leg). Bends: interior corner angles in degrees, comma separated — one fewer than the number of legs. Hooks and Laps: how many.

MarkØLegs (mm)Bends (°)HooksLapsCountCut (m)Mass (kg)

Results

Total bar length—
Net mass—
Waste allowance%
Order mass (with waste)—

Method

Massm = ρ · (π/4) · d² with ρ = 7850 kg/m³. This reproduces the published nominal mass table exactly (Ø12 → 0.888 kg/m), so no copyrighted table is copied — the numbers come from physics.
Bend deductionThe sum of outside leg dimensions overstates the steel, because the corner is a virtual point the bar never reaches. For a bend of angle θ, inside radius r and diameter d: setback per leg = (r+d)·tan(θ/2), centreline arc = (πθ/180)·(r+d/2), deduction = 2·setback − arc.
Why the site rule is "2d"Put r = 2d and θ = 90° into the formula above and it returns 2.073 d. The familiar site table (45°=1d, 90°=2d, 135°=3d) is not a separate truth — it is this geometry evaluated at one common mandrel size. It drifts as soon as r/d changes, which is why the comparison box above shows both.
HooksA hook is dimensioned by its straight tail beyond the bend, so its contribution is arc + tail. The virtual-corner deduction is not applied to hooks: at 135° or 180° that formula produces a large meaningless number.
Cross-checkBS 8666 shape code 11 is quoted in independent sources as a deduction of 0.5r + d. For Ø12 at r = 24 mm that is 24.0 mm against 24.9 mm here — agreement within 4%, the published figure being a rounded simplification.
ConfidenceLevel A for the geometry and the mass. The detailing values you enter (mandrel factor, hook tail, lap length) carry whatever confidence your source standard has — this tool neither supplies nor validates them.

Method: bend geometry + nominal mass (confidence A) ·

Take-off tool for ordering and cost estimation. Detailing values are yours to supply and to verify against the governing standard; lap positions, bar curtailment and splice staggering are not designed here.