Rebar Calculator

Reinforcing bar adds tensile capacity to concrete members such as slabs, footings, beams, columns, and walls. A material estimate needs more than a count of bars because diameter and cut length strongly affect steel weight. This calculator uses the common metric estimating relationship in which weight per meter equals the square of the nominal diameter in millimeters divided by 162. Multiplying that unit weight by total bar length gives the estimated order weight. Multiplying weight by a supplied price per kilogram produces a simple material-cost estimate. The diameter-squared formula is a practical expression of steel density and circular cross-sectional area. It is widely used for estimating standard carbon-steel reinforcing bars. Actual published mass per meter may differ slightly because standards specify nominal sizes and manufacturing tolerances. When procurement accuracy matters, use the mass table from the governing rebar standard or supplier. The calculator is best suited to preliminary quantities, budget checks, and comparisons between bar schedules. Length per piece should represent the cut or stock length being ordered, not just the clear span of a concrete member. Structural drawings may require development length, hooks, bends, laps, couplers, anchorage, and bar extensions. Those details increase total length and must be included in a takeoff. Quantity should cover every identical piece in the mark. Repeating the calculation for each bar mark and adding the weights produces a project total. A separate allowance can then cover cutting waste, detailing changes, damage, or minimum order quantities. Price per kilogram varies with grade, coating, bar size, fabrication, delivery, taxes, and market conditions. A zero price is allowed when only weight is needed. The resulting cost covers the entered raw steel quantity only; it does not include bending, placing labor, tying wire, chairs, couplers, equipment, or freight unless those charges are already included in the unit rate. Rebar design and placement must follow approved structural documents. This tool does not determine required diameter, spacing, cover, lap length, or steel grade. Those are engineering decisions affected by loads, exposure, concrete strength, seismic provisions, and applicable codes. Use the estimate to support purchasing and planning, then reconcile it with the final bar bending schedule and supplier documentation.