Rebar Calculation
Estimate mesh rebar length, bar count and weight from slab size, spacing and edge clearance.
How is it calculated?
Rebar (reinforcing steel) is patterned steel used to improve concrete tension capacity. In slabs it is typically laid as a mesh. The estimator finds grid size after edge clearance, counts bars from spacing, and totals length.
Steps
- Enter slab length and width in meters.
- Enter rebar-to-rebar spacing and edge-to-grid clearance in centimeters.
- Pick a rebar diameter; unit weight is estimated as d²/162 (kg/m) — changing diameter changes kg and cost.
- Enter rebar length (often 12 m). Optionally add a kg or ton price.
- Read estimated weight, total length, piece count and (if priced) weight × price.
Common diameters
Metric markets commonly use Ø8, Ø10, Ø12, Ø14, Ø16, Ø18, Ø20, Ø22 and Ø25 mm. Imperial sizes (#3–#8) are based on ⅛-inch steps; soft-metric equivalents are approximate mm diameters.
Field note
Bars are usually tied with wire rather than welded. Confirm spacing, edge clearance and diameter with the structural design; this tool gives guidance only.
Next: concrete and building budget
After rebar take-off, estimate slab concrete volume or official building unit cost from gross area: