Rebar Calculator — m, kg, cost
How to use this calculator
Choose an input mode: By Area + Spacing (enter slab/wall area and bar spacing in both directions), By Total Length (enter total linear meters needed), or By Quantity + Length (enter number of bars and individual bar length). Select the bar diameter from Ø6 to Ø32 mm and set the standard bar length (6 m or 12 m).
Lap splices are calculated per Eurocode 2 (EN 1992-1-1) at a default of 40 bar diameters. Waste allowance is adjustable from 0% to 25%.
Cost — price per linear meter, per kilogram, or per bar. Select your currency (EUR, PLN, CZK, SEK, etc.).
Tying wire — estimated at ~1.2 kg per 100 intersections.
Saved Calculations
| Time | Bar | Mode | Length m | Bars | Weight kg | Cost |
|---|
How to Calculate Rebar Quantity (Metric)
This rebar calculator estimates the total length, number of bars, weight, lap splices, and cost for reinforcing steel. Three input modes are supported: by area with bar spacing (for slabs, walls, and footings), by total linear meters, or by specifying a quantity and individual bar length. Bar diameters range from Ø6 mm (0.222 kg/m) to Ø32 mm (6.313 kg/m) per B500B grade steel (EN 10080).
Lap Splices per Eurocode 2
When a single bar cannot span the full length, lap splices are required. Standard lap splice length per EN 1992-1-1 is approximately 40 bar diameters for good bond conditions and 50 bar diameters for poor bond conditions. For example, Ø12 bar requires a lap splice of 480 mm (40 x 12 mm). The calculator accounts for the extra length consumed by each splice.
Waste Allowance
Cutting waste varies from 5% for straight runs to 15-20% for complex shapes. The default 10% is suitable for most typical slab and footing applications. Standard bar lengths in Europe are 6 m and 12 m.
Tying Wire
Rebar intersections are secured with 1.2 mm black annealed tying wire. The calculator estimates approximately 1.2 kg of wire per 100 intersections, which accounts for double ties and waste.
