Where does d²/162.28 come from?

It is the rebar weight formula derived from steel density (7850 kg/m³): weight per meter = π/4 × d² × 7850, simplified to d²/162.28 with d in mm.

How accurate is this?

Within about ±3% of mill certificates. Deformed bars carry ribs that add a little weight over plain rounds.

Can I estimate steel for a whole slab?

Rough planning uses 80 to 120 kg per m³ of concrete, but final quantities must come from the structural drawings and a bar-bending schedule.

Steel Rebar Weight Calculator - kg per Meter & Total

Rebar weight from bar diameter using d²/162.28, with totals for any bar length and count.

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Know the Weight Before the Truck Arrives

Steel is sold by weight, but drawings count bars. AiLoveKit's steel calculator bridges the gap: pick a diameter, enter bar length and count, and get unit weight (kg/m) plus the total order weight using the standard d²/162.28 formula. Useful for checking deliveries, estimating saria budgets and converting bar lists to kilograms.

Typical Unit Weights

8 mm - 0.395 kg/m
12 mm - 0.888 kg/m
16 mm - 1.578 kg/m
25 mm - 3.853 kg/m

Combine with the Concrete Calculator to budget both materials together.