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Reinforcing steel grid

Rebar calculator

A 10 × 10 ft grid at 24 in maximum spacing, with zero edge offset for illustration, has 6 bars each way. Enter the spacing, edge offsets and laps from your approved design to estimate stock lengths.

Example measurements. Replace them with your project dimensions and approved product specifications.

Measured project length. Deck boards run along this direction.
ft
Measured project width, perpendicular to the length.
ft
Example only. Use the edge-to-bar-center distance on your approved drawing. This tool does not select code-required concrete cover.
in
Example only. Enter the center-to-center spacing from the approved design; the outermost bars are included.
in
The length of the bars your supplier sells.
ft
Required when a run exceeds one stock bar. Use the engineered lap length; this calculator does not design splices.
in
Your allowance for cuts, breakage and spare material. Zero adds no extra; choose the allowance for your project.
%
Use your supplier's quote. The estimate excludes labor, taxes and delivery.
$

Spacing, cover, bar size, laps and number of layers come from your approved drawings. This is a rectangular, single-layer quantity estimate, not a reinforcement design. Cut reuse is considered within each direction for runs shorter than stock; spliced runs use a conservative whole-stock count.

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How the rebar calculator works

Runs in each direction = round up (clear perpendicular span ÷ maximum spacing) + 1. Long runs include specified lap lengths; stock lengths are counted before the extra allowance.

Worked example

With a clear 10 ft span and 2 ft spacing, there are 5 spaces and 6 bars. Both directions need 12 runs of 10 ft in total. Six 20 ft stock bars can supply those cuts when there are no laps and both cuts fit. Edge offset is zero only in this arithmetic example.

Reference quantities

Examples only, with no extra allowance: 10 ft length, 24 in spacing, zero edge offset, 20 ft stock and 24 in laps where required.

Area (sq ft)Example quantity
604 stock bars
12010 stock bars
24019 stock bars
40029 stock bars

Before you buy

This is a single rectangular layer, with no hooks, dowels, chairs, tie wire, bends or weight estimate. Enter edge-to-bar-center offsets, not nominal face cover without adjustment. Long spliced runs use conservative stock counts and do not reuse offcuts. Your designer determines bar size, spacing, cover, splice details and number of layers.

Can the calculator choose my rebar spacing or lap length?

No. Copy those values from an approved design. A quantity estimate cannot determine whether the reinforcement is adequate. Runs longer than the stock length require a specified lap; the calculator rejects such runs when no lap is entered.

Sources & method

Rebar product and estimating reference. Measurement conversion: NIST international foot. How we calculate.

Keep each part of your project separate so its dimensions, allowance and purchase units stay clear. Save the results to the same project list when you are ready.

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