About

In structural engineering and construction estimating, accuracy in material quantification is the difference between a profitable project and a budget overrun. This calculator addresses the specific complexity of reinforcement cages used in beams and columns, where main longitudinal bars and transverse stirrups (ties) contribute differently to the total tonnage.

Standard linear weight calculations often fail to account for the density variances between different bar diameters or the cumulative length of stirrups wrapping around the core. This tool parses the cage geometry to provide a precise breakdown of steel weight, allowing site managers and quantity surveyors to order exact amounts and forecast costs with high confidence.

Formulas

The total weight is the sum of the longitudinal (main) bars and the transverse stirrups.

W_total = (N_main × L_beam × w_main) + (N_stirrup × L_stirrup × w_stirrup)

Where stirrup length L_stirrup is calculated based on the perimeter minus cover plus hook lengths:

L_stirrup ≈ 2(W + H) − 8c + L_hooks

Reference Data

Diameter (Ø)	Weight (kg/m)	Weight (lb/ft)	Section Area (mm²)	Common Usage
6 mm	0.222	0.149	28.3	Stirrups / Light Mesh
8 mm	0.395	0.265	50.3	Stirrups / Ties
10 mm	0.617	0.414	78.5	Light Main Bars
12 mm	0.888	0.597	113.1	Standard Main Bars
16 mm	1.580	1.062	201.1	Heavy Main Bars
20 mm	2.466	1.657	314.2	Column Verticals
25 mm	3.853	2.589	490.9	Heavy Load Beams
32 mm	6.313	4.242	804.2	Bridge Piers
40 mm	9.865	6.629	1256.6	Massive Foundations

Frequently Asked Questions

Estimators sometimes calculate stirrup length based solely on the concrete section dimensions without accounting for hook lengths (usually 9d to 12d at corners) or the density of spacing near support zones (plastic hinge regions), where stirrups are often doubled.

Yes. Concrete cover is the protective layer of concrete between the steel surface and the exterior. The calculator subtracts this cover from the beam/column dimensions to determine the actual perimeter of the stirrup.

Standard seismic detailing often requires a 135-degree hook. A common rule of thumb for estimation is to add approximately 100mm to 150mm total per stirrup for hooks, or roughly 6 to 10 times the bar diameter per hook depending on the code (ACI vs Eurocode).

This tool calculates the net weight of the cage geometry. For long spans requiring splices (overlaps), industry standard is to add a 3-5% waste or overlap factor to the final tonnage.