Rebar Calculator
Enter rebar grid size and spacing to instantly compute bar count, total length, weight and cost. Essential for slab, footing and beam/column reinforcement.
Input Data
Results
At a glance:The rebar calculator uses a "grid bar count × theoretical weight" model. Count bars in each direction by spacing (round up, add one); bar lengths are grid length and width; add lap length per bar for total length. Weight per metre uses steel density 7,850 kg/m³ and circular cross-section; total weight = total length × weight per metre; cost = total weight × price per ton.
Formula
Longitudinal bars n₁ = ⌈width ÷ spacing⌋ + 1
Transverse bars n₂ = ⌈length ÷ spacing⌋ + 1
Total length L = n₁×length + n₂×width + (n₁+n₂)×lap
Weight per metre W = π×(d/1000)²/4 × 7850
Total weight = L × W
Example: 10m×6m, 0.2m spacing, T16 → ~31+51 bars, ~1,800 kg
$$n_1 = \left\lceil \frac{W}{s} \right\rceil + 1$$$$n_2 = \left\lceil \frac{L}{s} \right\rceil + 1$$$$L_t = n_1 L + n_2 W + (n_1+n_2) o$$$$w = \frac{\pi d^2}{4} \times 7850 \times 10^{-6}$$$$M = L_t \times w$$How to Use
- Enter the grid length and width.
- Set the bar spacing (slabs 150–300 mm).
- Enter the lap length (about 0.4 m, adjust to drawings).
- Select the rebar diameter (T10–T32).
- Enter price per ton to estimate cost.
- The tool outputs bar counts, total length, weight and cost.
Case Studies
Ground slab mesh
10×6 m, 200 mm spacing, T16, lap 0.4 m.
31 longitudinal + 51 transverse bars; total weight about 1,024 kg.
Footing mesh
5×5 m, 150 mm spacing, T12, lap 0.4 m.
35+35 bars; total weight about 480 kg.
Project quote
Enter price per ton after estimating weight.
Total cost = weight (tonnes) × price per ton.
FAQ
Why round up and add one?
Bars must cover both edges, so count = ⌈side ÷ spacing⌋ + 1; rounding up guarantees full coverage.
How to choose spacing?
Spacing depends on design load; slabs commonly 150–300 mm. Follow the structural drawing; this calculator only estimates quantity.
What is lap length?
When a bar is too short, bars overlap to splice; lap is usually 40–50× diameter. It adds to total length and weight.
How to read T16?
T stands for deformed (high-tensile) bar; T16 means 16 mm diameter. Weight per metre ≈ 1.58 kg/m.
Does this include stirrups?
No. This estimates straight bars in a grid; stirrups and ties are counted separately.
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.