Rebar Spacing Calculator
Bar spacing for a required steel area per metre — slab detailing in one step.
Code caps: 3d or 300 mm (main), 5d or 450 mm (distribution). '10Ø @ 150 c/c' = 523 mm²/m — the slab detailer's lingua franca.
Formula
Rebar Spacing Calculator is a free rebar spacing for structural engineers, fabricators and site engineers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Rebar Spacing Calculator
Bar spacing for a required steel area per metre — slab detailing in one step. The calculation implements s = 1000·A_bar/A_st,req (IS 456 cl. 26.3.3). Code caps: 3d or 300 mm (main), 5d or 450 mm (distribution). '10Ø @ 150 c/c' = 523 mm²/m — the slab detailer's lingua franca.
How to use Rebar Spacing Calculator
- 1Enter Required steel area in mm²/m.
- 2Enter Bar diameter in mm.
- 3Read Required spacing c/c, Provide (rounded down to 25), A_st provided instantly — no submit button needed.
Why use Rebar Spacing Calculator?
- ✓Implements the standard formula — s = 1000·A_bar/A_st,req
- ✓Reference cited on-page: IS 456 cl. 26.3.3
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Rebar Spacing Calculator use?+
It computes s = 1000·A_bar/A_st,req, per IS 456 cl. 26.3.3. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
Code caps: 3d or 300 mm (main), 5d or 450 mm (distribution). '10Ø @ 150 c/c' = 523 mm²/m — the slab detailer's lingua franca.
Can I use this for real structural design?+
It implements the exact textbook/code formula cited below the result and is ideal for sizing, checking and learning. Final designs should be verified by a qualified engineer against the full code with all load cases.
Is the Rebar Spacing Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
Related Engineering tools
Reynolds Number Calculator
Compute Re from density, velocity, pipe diameter and viscosity — with instant laminar/turbulent classification.
● LiveLaminar vs Turbulent Flow Classifier
Classify hydraulic-oil or process-fluid flow regime from kinematic viscosity, line velocity and tube bore.
● LiveBernoulli Equation Solver
Solve downstream pressure between two points from velocities, elevations and fluid density (ideal, lossless).
● Live