How much does rebar weigh?

#3: 0.376 lb/ft; #4: 0.668 lb/ft; #5: 1.043 lb/ft.

3 in against soil, 1½–2 in for slabs on grade with a vapor barrier.

Wire mesh is faster for slabs; bars handle loads and edges better.

Mesh saves time on slabs; rebar suits edges and point loads.

How much steel in a slab?

It depends on design; residential slabs often use #3 or #4 at 12–18 in.

Rebar calculator

Slab size, spacing, bar size, cover and stock length: you get bars each way, total length, stock bars, weight and chairs.

Purchase quantity

705.545 ft

Net measurement: 641.404 ft · Waste 10 %

Rebar bars36 bar
Steel weight292.531 lb
Bars in both directions45 unit
Rebar chairs (4 per m²)77 unit

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How it's calculated (visible formula)

bars = ⌊side ÷ spacing⌋ + 1 each way; length = Σ bars × length; kg/m = 0.00617 × Ø²

Net geometric measurement, no waste.
Adjustable waste % for cuts and breakage.
Purchase rounded up to sellable units (boxes, bags, buckets, boards).

See methodology and formula versions

How to calculate it, step by step

Measure slab length and width.
Subtract concrete cover at each edge.
Set bar spacing and size.
Work out bars each way and total length.
Convert to stock bars, weight and chairs.

Worked example: 16 × 13 ft slab, #3 (10 mm) at 8 in, 2 in cover

20 bars of 16 ft + 25 of 12.8 ft ≈ 641 ft (195.5 m)
+10% ≈ 705 ft → 36 bars of 20 ft
≈ 293 lb

→ 36 bars of #3 (≈ 10 mm) and 77 chairs.

Common mistakes

Forgetting cover when cutting bars.
Ignoring lap splices on long slabs.
Laying mesh on the ground without chairs.

Pro tips

Tie intersections at least every second or third crossing.
Use chairs to hold bottom cover.
Lap bars about 40–50 diameters per the engineer.
Have the rebar inspected before the pour.

From calculation to quote

Add labour, overhead and your margin, and generate the professional PDF.

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FAQs

How much does rebar weigh?: #3: 0.376 lb/ft; #4: 0.668 lb/ft; #5: 1.043 lb/ft.
How much cover?: 3 in against soil, 1½–2 in for slabs on grade with a vapor barrier.
Mesh or bars?: Wire mesh is faster for slabs; bars handle loads and edges better.
Wire mesh or rebar?: Mesh saves time on slabs; rebar suits edges and point loads.
How much steel in a slab?: It depends on design; residential slabs often use #3 or #4 at 12–18 in.
How much cover in a footing?: 3 in against soil.

Sources and standards

Maintained by Srikanta M · Formula v1.0.0 · Verified 2026-09-10 · Updated 2026-09-10 · Limits: quantity estimation, not structural design or site supervision.