Rebar Calculator

Estimate two-way rebar grid runs, linear feet, entered-weight totals and stock bars, including both edges and off-spacing dimensions. Calculate it clearly with Figur.

Count both directions of a rectangular rebar grid

Lengthwise runs = round up(width × 12 ÷ spacing − 0.000000001) + 1; crosswise runs use length instead of width. The tiny subtraction avoids an extra run from floating-point error at exact multiples. Total feet = lengthwise runs × length + crosswise runs × width. Bars = round up(total feet ÷ stock bar length). Weight = total feet × entered pounds per foot. Dimensions and stock length are in feet; spacing is in inches.

Method and assumptions

Runs across a dimension = round up(dimension × 12 ÷ spacing − 0.000000001) + 1. Total feet = lengthwise runs × length + crosswise runs × width; bars = round up(total feet ÷ bar length); pounds = total feet × lb/ft.

  • A single rectangular two-way grid includes both edge runs. Off-multiple dimensions add a run instead of increasing the requested spacing.
  • Enter whole-inch spacing from 4 to 36. Bar weight is entered, not inferred from bar diameter.
  • Stock bars are estimated from aggregate linear footage. Cuts, offcut reuse and individual run lengths are not optimized; this is not a guaranteed purchasable cutting list.
  • Concrete cover, lap splices, bends, chairs, ties, dowels, corner bars and structural/code design are excluded. No separate waste allowance is applied.

Planning takeoff, not a binding bid, structural design or engineering advice. Confirm field measurements, product coverage, installation requirements and supplier quantities before buying.

Sources and references

The result uses your inputs and the tool's documented assumptions; it does not fetch current prices, rates or products.

Worked example

A 20 × 12.5 ft grid uses 12-inch spacing, 20 ft stock bars and #4 weight entered as 0.668 lb/ft.

Lengthwise runs: round up(150 ÷ 12) + 1 = 14; crosswise: 240 ÷ 12 + 1 = 21. Total: 14 × 20 + 21 × 12.5 = 542.5 ft (displayed as 543 ft). Weight: 542.5 × 0.668 = 362.39 lb. Round up 542.5 ÷ 20 = 27.125 to 28 bars.

Frequently asked questions

What happens when a dimension is not divisible by spacing?

The run count rounds up before adding the edge run. For 12.5 ft at 12 inches, it counts 14 runs, not 13.

Does stock-bar rounding ensure all cuts fit?

No. Total feet divided by stock length is an aggregate estimate; actual cuts and lap requirements can require more bars.

Does it deduct concrete cover or add laps?

No. Grid dimensions are exactly those entered. Get cover, lap lengths, bends and reinforcement requirements from the approved plan.

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