Concrete Slab Reinforcement Calculator

Measurement inputs

Live calculation updates as you type.

Live

Project name Used in the saved report.

Unit system Switches starter units only.

Slab size

Slab length

Slab width

Slab thickness

Rebar layout

Lengthwise bar spacing

Bars run along length. Spacing is across slab width.

Crosswise bar spacing

Bars run along width. Spacing is across slab length.

Edge cover

Distance from slab edge to first bar.

Bar size Common US rebar sizes.

Ordering options

Lap / waste allowance (%)

Stock bar length

Cost per stock bar

Total order length with allowance

Includes lap and waste allowance.

–

Stock bars to buy –

Total rebar weight –

Lengthwise bars –

Crosswise bars –

Base bar length –

Usable slab area –

Actual lengthwise spacing –

Estimated cost –

This is an estimating tool. Confirm reinforcement layout, splice rules, cover, and bar size with your engineer or local code before ordering.

Bar count = ceil(usable dimension ÷ spacing) + 1

Total length = lengthwise bars × usable length + crosswise bars × usable width

Unit note: all measurements are converted to feet for calculation. Metric results are converted back to meters and kilograms.