What formulas does the calculator use?

For spacing-to-count, it uses n = floor(b/s) + 1 and bars/m = 1000/s. For count-to-spacing, it uses s = b/(n-1).

What unit of measurement should I use?

All physical dimensions for width (b) and spacing (s) must be entered in millimeters (mm).

Why does the spacing-to-count formula use the floor function?

The floor function ensures that the calculated number of bars fits within the specified width without exceeding the maximum allowable spacing.

Can I calculate the spacing if I only know the total number of bars?

Yes, switch the mode to 'Count → spacing', enter the total width and the number of bars (minimum 2), and the tool will calculate the exact spacing.

How does the tool calculate the bars per meter value?

It divides 1000 mm by the spacing (s) to give you the standardized density of reinforcement per linear meter.

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Rebar Spacing Calculator

Calculate rebar spacing and bar count over a width b perpendicular to the bars. From spacing: n = floor(b/s)+1, bars per meter = 1000/s. From count: spacing s = b/(n−1). All lengths in mm.

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2 examples

b=1000 mm, s=200 mm → n=6, 5.0 bars/m

n = floor(1000/200) + 1 = 5 + 1 = 6 bars. Bars per meter = 1000/200 = 5.0.

{"result":"Width b=1000 mm, spacing s=200 mm. n = floor(b/s)+1 = floor(1000/200)+1 = 6 bars. Bars per meter = 1000/s = 5.00 /m.","metadata":{"input":{"mode":"fromSpacing","b":1000,"s":200},"result":{"mode":"fromSpacing","count":6,"spacing":200,"perMeterCount":5,"perMeterUnit":"/m"}}}

b=1200 mm, n=7 → s=200 mm, 5.0 bars/m

s = b/(n−1) = 1200/(7−1) = 200 mm. Bars per meter = 1000/200 = 5.0.

{"result":"Width b=1200 mm, n=7 bars. s = b/(n−1) = 1200/6 = 200.00 mm. Bars per meter = 1000/s = 5.00 /m.","metadata":{"input":{"mode":"fromCount","b":1200,"n":7},"result":{"mode":"fromCount","count":7,"spacing":200,"perMeterCount":5,"perMeterUnit":"/m"}}}

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5 options

SettingsAdjust formats, ranges, numbers, and modes.5

Calculation ModeselectOptionalWidth b (mm)numberRequiredSpacing s (mm)numberOptionalUsed in 'Spacing → count' mode.Number of Bars nnumberOptionalUsed in 'Count → spacing' mode. Must be ≥ 2.Decimal PlacesnumberOptional

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Rebar Spacing Calculator

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Examples

1. Determining Bar Count for a Concrete Slab

2. Calculating Spacing for a Fixed Number of Bars

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