Rebar Grid Spacing Chart
Bar counts, linear feet and weight of #4 reinforcement in a 20 × 12 ft slab at grid spacings from 4 to 24 inches. Steel is bought by weight, so the last column is the one the yard quotes against.
Source data and formula checked · How we check
Rebar Grid Spacing Chart reads total bar length straight off grid spacing, for 10 values from 4 to 24. Every row is computed from the same formula the calculator uses, not measured or copied from another table, so a value between two rows can be worked out the same way. The formula is the one published by Concrete Reinforcing Steel Institute.
For #4 bar at 0.668 lb per foot with 3 in cover. Other sizes scale by their own weight per foot.
| Grid spacing (inch) | Total bar length | Bars running lengthwise | Weight of steel |
|---|---|---|---|
| 4 | 1,361 ft | 35 bars | 909.15 lb |
| 6 | 928 ft | 24 bars | 619.9 lb |
| 8 | 696 ft | 18 bars | 464.93 lb |
| 10 | 549 ft | 14 bars | 366.73 lb |
| 12 | 464 ft | 12 bars | 309.95 lb |
| 14 | 391 ft | 10 bars | 260.85 lb |
| 16 | 348 ft | 9 bars | 232.46 lb |
| 18 | 317 ft | 8 bars | 211.76 lb |
| 20 | 275 ft | 7 bars | 183.37 lb |
| 24 | 232 ft | 6 bars | 154.98 lb |
Questions people actually ask
- How do I read the Rebar Grid Spacing Chart?
- Find your grid spacing in the first column and read across. At 4 inch the total bar length is 1,361 ft; at 24 inch it is 232 ft. The table runs from 4 inch to 24 inch in 10 rows.
- Can I read between two rows?
- Not by splitting the difference. The total bar length does not change by the same amount from row to row, so the midpoint of two rows is not the answer for the midpoint of two grid spacing values. Put the exact figure into the calculator instead — it uses the same formula that produced every row here.
- What if my grid spacing is outside the table?
- The chart covers 4 inch to 24 inch, which is the range people actually look up. Anything above or below goes into the calculator, which takes any figure and shows each step of the working rather than only the result. Open the rebar calculator.
- Where do these numbers come from?
- Every row is computed at build time from the formula published by Concrete Reinforcing Steel Institute, by the same code behind the calculator — not transcribed from another table, which is how a rounding error in one chart ends up in twenty.
Need a different number?
The chart covers the common values. For anything between the rows, the rebar calculator takes any figure and shows the working.
Source: Concrete Reinforcing Steel Institute, American Concrete Institute — ACI 318 building code