RenoMetric
Concrete & Masonry

Rebar Spacing Calculator

What you will get

1. Needed

See the estimated project quantity from your measurements.

2. Buy

Add waste and round to complete bags, boxes, cans, bundles or delivery quantities.

3. Check

Review product coverage, site conditions, local requirements and supplier details before ordering.

Quick answer: Estimate the number of reinforcing bars across a slab width using bar spacing and edge clearance in Imperial or Metric units. Start with actual measurements, use the product label for coverage or yield, and treat the result as a planning estimate until site conditions and supplier requirements are confirmed.

Estimate the number of reinforcing bars needed across a slab width, with a visible edge allowance.

Project inputs

Enter spacing details

Transparent formula

How the bar count is calculated

The calculator subtracts both edge clearances, divides the usable width by the selected spacing, rounds up, and adds one bar for the starting edge.

usable width = slab width − 2 × edge clearance
bars = ceil(usable width ÷ spacing) + 1

Planning only: final reinforcement layout, bar size, cover, lap lengths and maximum spacing limits must come from the structural drawings and applicable local requirements.

Related tools

Rebar Quantity Calculator · Rebar Weight Calculator