Sources and scope for this page: Formulas as shown on this page (standard engineering relationships, no single governing revision), covering every value this calculator produces. No independent source check is recorded for this page: the content rests on the sources listed and on the working shown on the page. Full sources, values and limits on this page.
Page last changed 2026-10-19 · based on n/a — standard engineering relationships, no single governing revision
Quick Answer
Rebar Weight
The Formulas Used
weight per foot = (π/4) × d² × 0.2836 × 12
Bar number is the diameter in eighths of an inch for #3 through #8: d = number ÷ 8.
Weight Scales with Diameter Squared
Doubling the bar diameter quadruples the weight per unit length, because weight follows the cross-sectional area. That is why the step from #8 to #11 nearly doubles the weight per foot while the diameter rises by only 41%.
Weight is what rebar is bought and priced on, so it is the figure a takeoff needs. Use the rebar size chart for the tabulated values per bar size.
Where the Bar Number Breaks Down
The bar number is the diameter in eighths of an inch only up to #8. Above that the sizes were set separately, so #9 is 1.128 in rather than 1.125, and #14 is 1.693 in rather than 1.75. The calculator above uses the actual diameter, so it stays correct across the whole range.
Frequently Asked Questions
- How much does #5 rebar weigh per foot?
- 1.043 lb/ft, or 1.552 kg/m. The bar is 0.625 in in diameter with a cross-sectional area of 0.307 in².
- How do I calculate rebar weight?
- Weight per foot = (π/4) × diameter² × 0.2836 × 12. Multiply by the total length for the job. Doubling the diameter quadruples the weight.
- What size is #4 rebar?
- #4 rebar is 0.500 in (12.7 mm) in nominal diameter. The bar number is the diameter in eighths of an inch for sizes up to #8.
- How many #4 bars are in a ton?
- At 0.668 lb/ft, a ton (2,000 lb) is about 2,994 ft of #4 bar — roughly 375 bars at 8 ft, or 250 at 12 ft.
- Does rebar weight affect concrete cover?
- Indirectly. Cover is specified as a distance from the concrete surface to the bar, so larger bars place their centre further in for the same cover. The governing requirement is in the applicable building code.
Related
Value Sources
References and calculation methods used for this page are listed below. Numbered markers connect table columns where present. A reference listing does not itself establish that every value has been independently checked.
| # | Source | Type | Revision / method |
|---|---|---|---|
| [1] | ASTM A615 — Deformed steel bars for concrete reinforcement | reference | ASTM A615/A615M-20 — source |
| [2] | Values computed in your browser | derived | Evaluated locally from the formulas shown on the page. No data leaves the device. |
Data Sources
| Standard | Revision | What it covers on this page |
|---|---|---|
| Formulas as shown on this page | n/a — standard engineering relationships, no single governing revision | every value this calculator produces |
Verification scope
No page-specific independent source review is recorded here. The listed references and formulas explain the basis of the compilation; automated consistency checks do not verify the original sources or establish product conformity.
Derived values — the following values on this page are calculated, not taken directly from the standard:
| Value | How it is derived |
|---|---|
| All outputs | Computed in the browser from the formulas above. No data leaves the device. |
Outputs are computed from the formulas shown. Verify against the governing standard for design or acceptance work.
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