Rebar Calculator
Estimate rebar quantity, total length and weight for slabs, footings and walls.
How to use this tool
- Choose the element (slab, footing, wall) and enter its dimensions.
- Set rebar size and spacing in both directions.
- Add wastage for laps and offcuts.
- Click Calculate for bar count, total length and weight.
How it works
Bars per direction = length / spacing + 1 (first bar). Total length = bars x span. Weight per meter comes from the bar's cross-section and steel density (7850 kg/m³).
Tips
- Check your local code for minimum bar size and spacing.
- Count corner and edge bars explicitly — they're often extra.
- Order 10–15% more to cover laps and cutting waste.
Limitations
Design guides (bar schedules) should come from a structural engineer for load-bearing elements.
Frequently asked questions
What rebar spacing should I use?
Common values are 12 in, 16 in or 24 in on center depending on load and code. The calculator lets you set any spacing.
How is rebar weight calculated?
Rebar weight depends on bar size (diameter). Standard density is 7850 kg/m³; the common approach uses weight per unit length for each bar size.
Do I need laps and overlaps added?
Yes — most codes require laps at splices. Add 10–20% for laps and waste; the calculator includes a wastage field.