How to use the rebar quantity calculator
This calculator helps you calculate grid bar counts, steel weight and material cost for one reinforcement layer. It is intended for quantity takeoffs, early budgets and checks against a measured schedule. Start with the dimensions or quantities for one clearly defined item of work. Enter values in the units shown beside each field; millimetres and metres are not interchangeable.
Area alone does not define a grid: enter slab length so width can be calculated as area ÷ length. One layer, bars at both edges, no cover deduction, laps, stock-length cutting or waste.
Worked example
For 24 m² at 6 m length, width is 4 m. At 200 mm centres both ways, there are 21 lengthwise bars and 31 crosswise bars.
Before you order
Compare the result with your drawings and supplier information. Keep the original net quantity separate from allowances, and round purchasing quantities only at the ordering stage. Check whether delivery, labour and related materials belong elsewhere in your estimate. If the drawing or specification changes, update the inputs and record the revised basis instead of reusing an earlier total.
For the concepts behind this calculation, read Rebar (Reinforcement Steel), Lap Length, Wastage Factor.