How to Calculate Rebar Spacing
What is Rebar Spacing?
Reinforcement bar spacing determines concrete coverage and structural capacity. Adequate spacing ensures proper concrete consolidation and strength.
Step-by-Step Guide
- 1Minimum spacing typically 1.5× bar diameter or 40 mm, whichever is larger
- 2Account for aggregate size (spacing > 1.3× max aggregate diameter)
- 3Calculate based on cover requirements and member width
Worked Examples
Input
#25 rebars (25 mm), clear cover 50 mm, beam width 400 mm
Result
Maximum ~4 bars fit with 50 mm spacing
Detailed calculation
Common Mistakes to Avoid
- ✕Neglecting concrete cover in spacing calculations
- ✕Over-crowding reinforcement in small beams
Frequently Asked Questions
Why space rebar widely?
Concrete must flow around bars; tight spacing creates voids, reducing strength.
What if spacing is too tight?
Concrete won't fully consolidate; hidden voids reduce strength and durability.
Ready to calculate? Try the free Rebar Spacing Calculator
Try it yourself →