How much does rebar weigh? Here is the rebar weight chart for US bar sizes #3 to #18 in pounds per foot, with diameters, areas and weight per 20 ft bar, the simple formula behind it, and a free calculator for bars or a whole slab grid.
| #3 (⅜ in) | 0.376 lb/ft · 7.5 lb per 20 ft |
|---|---|
| #4 (½ in) | 0.668 lb/ft · 13.4 lb per 20 ft |
| #5 (⅝ in) | 1.043 lb/ft · 20.9 lb per 20 ft |
| #6 (¾ in) | 1.502 lb/ft · 30.0 lb per 20 ft |
| #8 (1 in) | 2.670 lb/ft · 53.4 lb per 20 ft |
Rebar weight chart (#3 to #18)
| Bar size (soft metric) | Nominal diameter | Area | Weight (lb/ft) | Weight per 20 ft bar | Metric weight |
|---|---|---|---|---|---|
| #3 (#10) | 0.375 in | 0.11 in² | 0.376 | 7.52 lb | 0.560 kg/m |
| #4 (#13) | 0.500 in | 0.20 in² | 0.668 | 13.36 lb | 0.994 kg/m |
| #5 (#16) | 0.625 in | 0.31 in² | 1.043 | 20.86 lb | 1.552 kg/m |
| #6 (#19) | 0.750 in | 0.44 in² | 1.502 | 30.04 lb | 2.235 kg/m |
| #7 (#22) | 0.875 in | 0.60 in² | 2.044 | 40.88 lb | 3.042 kg/m |
| #8 (#25) | 1.000 in | 0.79 in² | 2.670 | 53.40 lb | 3.973 kg/m |
| #9 (#29) | 1.128 in | 1.00 in² | 3.400 | 68.00 lb | 5.060 kg/m |
| #10 (#32) | 1.270 in | 1.27 in² | 4.303 | 86.06 lb | 6.404 kg/m |
| #11 (#36) | 1.410 in | 1.56 in² | 5.313 | 106.26 lb | 7.907 kg/m |
| #14 (#43) | 1.693 in | 2.25 in² | 7.650 | 153.00 lb | 11.384 kg/m |
| #18 (#57) | 2.257 in | 4.00 in² | 13.600 | 272.00 lb | 20.239 kg/m |
Rebar weight formula
- Weight (lb/ft) = 2.67 × d², where d is the nominal diameter in inches (steel at 490 lb/ft³). Check: #4 = 2.67 × 0.5² = 0.668 lb/ft.
- Diameter from the bar number: for #3 to #8, divide the number by 8 (#6 = 6/8 = ¾ in).
- Total weight = number of bars × length of each bar (ft) × weight per foot.
- In metric, the same idea gives the familiar D²/162 formula (kg/m with D in mm).
Rebar for common slab sizes
| Slab | Bar & spacing | Bars each way | Total length | Weight | 20 ft bars (+10%) |
|---|---|---|---|---|---|
| 10 × 10 ft | #3 @ 12 in | 10 + 10 | 190 ft | 71 lb | 11 |
| 10 × 10 ft | #4 @ 18 in | 7 + 7 | 133 ft | 89 lb | 8 |
| 20 × 20 ft | #4 @ 18 in | 14 + 14 | 546 ft | 365 lb | 31 |
| 24 × 24 ft | #4 @ 18 in | 16 + 16 | 752 ft | 502 lb | 42 |
| 24 × 24 ft | #5 @ 12 in | 24 + 24 | 1,128 ft | 1,177 lb | 63 |
Worked examples
1. A 20 × 20 ft slab, #4 at 18 in both ways
- Bars stop 3 in from each edge, so each bar is 20 − 0.5 = 19.5 ft long
- Bars across 19.5 ft at 18 in: 19.5 ÷ 1.5 = 13, plus 1 = 14 bars each way (28 total)
- Total length = 28 × 19.5 = 546 ft
- Weight = 546 × 0.668 = 365 lb; with 10% extra about 401 lb, or 31 bars of 20 ft
2. Ten #5 bars, 20 ft long
- 10 × 20 ft × 1.043 lb/ft = 208.6 lb
Rebar grades and bar lengths
- Grade 60 (60,000 psi yield) is the most common grade for building work; Grade 40 is still sold for some light uses. Grade does not change the weight.
- Common stock lengths are 20 ft, with 40 ft and 60 ft from suppliers; home stores often sell shorter bars.
- Size marking: the rolled-in bar number is the size in eighths of an inch, or the soft-metric number (e.g. #4 / #13).
FAQ
How much does #4 rebar weigh?
0.668 lb per foot, so a 20 ft bar weighs about 13.4 lb and a 40 ft bar about 26.7 lb.
How much does #5 rebar weigh?
1.043 lb per foot, or about 20.9 lb for a 20 ft bar.
How much does #3 rebar weigh?
0.376 lb per foot, or about 7.5 lb for a 20 ft bar.
What is the formula for rebar weight?
Weight in lb/ft ≈ 2.67 × the diameter in inches squared. For #4 (0.5 in), 2.67 × 0.25 = 0.668 lb/ft.
How many 20 ft #4 bars are in a ton?
About 149. Each 20 ft #4 bar weighs 13.36 lb, and a US ton is 2,000 lb.
References: ASTM A615/A615M (carbon-steel deformed bars) and ASTM A706/A706M (low-alloy steel deformed bars) nominal dimensions and unit weights. Quantities exclude laps, hooks and dowels unless added.
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