RHACOVA

Free contractor tool

Rebar Calculator

Enter the area, the bar spacing you were given and the edge cover to see how many bars run each way, the total linear feet, the lap allowance and how many stock bars that comes to.

Grid and spacing

Spacing, cover, stock length and lap length come from your drawings or your supplier. This tool never chooses them for you.

Units

Switching converts what you typed, so the size stays the same. Units only — this never changes a currency.

Area length
Area width

How far the bars are held back from each edge.

Leave 0 to skip splices.

Added at each splice.

Your number. RHACOVA publishes no standard allowance.

Your result

Linear feet to buyGrid plus laps plus your allowance283.0 ft
Stock barsAt 20 ft each15 ea
Grid length before laps and waste269.5 ft
Lap allowance0.0 ft
Offcut allowance5.00%

Bars in each direction

Bars running the length19.50 ft each7 ea
Bars running the width9.50 ft each14 ea
Why this number?

barsAlongLength = floor((widthIn - 2*cover) / spacingAcross) + 1; barsAcrossWidth = floor((lengthIn - 2*cover) / spacingAlong) + 1; linearInches = Σ bars * barLength; withLaps = linearInches + splices * lap; order = withLaps * (1 + waste); stockBars = ceil(order / stockLength)

Inputs

Length
240.00 in
Width
120.00 in
spacingAlongLength
18.00 in
spacingAcrossWidth
18.00 in
edgeCover
3.00 in
stockBarLength
20.00 ft
lapLength
18.00 in
Waste allowance
5.00%

Results

barsAlongLength
7.00 ea
barsAcrossWidth
14.00 ea
linearFeet
269.50 ft
lapLinearFeet
0.00 ft
orderLinearFeet
282.98 ft
stockBars
15.00 ea

Formula rebar.rectangularGrid · engine shared.rebar@1.0.0 · rectangular-bar-grid · rounding half-even to 6 decimals.

A bar list is not a bid

Linear feet tell you what to order, and they stay on this page for your material list — the job bid prices the concrete pour, so you enter the pour's volume there yourself.

Build the job bid

Still no account, and nothing you type leaves your device. Signing in only comes up if you choose to save the bid as an estimate.

What this calculator counts

A two-way mat of straight bars in a rectangle. Bars start one edge cover in from the edge and repeat at the spacing you enter, so a clear span of S at spacing P holds floor(S ÷ P) + 1 bars. Each bar is cut to the clear dimension in its direction: the full dimension minus cover at both ends. The two directions are added to give the linear feet of bar in the grid.

Give a stock bar length and a lap length and the calculator also counts splices: a bar longer than one stock length needs ceil(bar ÷ stock) pieces, which means one lap fewer than that, and each lap adds its own length of bar. Leave the stock length at 0 and no splices are assumed at all.

The assumptions, stated openly

  • A flat rectangle. Openings, curves and stepped areas are not deducted.
  • Straight bars only — no hooks, bends, dowels, chairs, ties or corner bars.
  • Equal spacing in each direction, measured centre to centre.
  • Cover applied equally at all four edges.
  • Laps only where a bar is longer than one stock bar.
  • No bar size, grade, weight or price is assumed anywhere.

Change any of those on paper and the quantity changes. If the drawings call for corner bars, extra bars at openings or a second mat, add them to the result yourself.

Not an engineering tool

Bar size, spacing, cover, lap length and whether reinforcement is required at all are structural and code questions. RHACOVA takes them as inputs and never suggests, validates or approves them. Use the values on your drawings.

Worked example

A 20 ft × 10 ft slab, bars at 18 in each way, 3 in edge cover, 20 ft stock bars, 18 in laps and a 5% offcut allowance:

  • Bars running the length: 7 ea at 19.50 ft
  • Bars running the width: 14 ea at 9.50 ft
  • Grid length: 269.5 ft
  • Lap allowance: 0.0 ft
  • Linear feet to buy: 283.0 ft — 15 ea stock bars

The example is produced by the same engine as the calculator above, so the two always agree.

Other concrete quantities

After the quantity: cost, price, profit

  • True Job Cost Calculator

    A quantity is not a cost. Add material, loaded labor, equipment, disposal and the rest to see what the pour actually costs you.

  • Markup & Margin Calculator

    Turn that cost into a price, and see the margin the price actually leaves.

Learn the method