Round bar weighs 2.673 × d² pounds per foot, square bar 3.403 × s², and flat bar 3.403 × width × thickness, all in inches at 490 lb/ft³. A 1 in round bar is 2.67 lb/ft, so a 20 ft length weighs 53.5 lb. A 1 in square bar is 3.40 lb/ft. A 4 × 1/2 in flat is 6.81 lb/ft.
The formulas
Steel weighs 490 lb per cubic foot, so one square inch of cross section, one foot long, weighs 490 / 144 = 3.403 lb. Every bar weight follows from the area.
Flat bar: lb/ft = width × thickness × 3.403Square bar: lb/ft = side² × 3.403
Round bar: lb/ft = diameter² × 2.673
All dimensions are in inches. The round factor is 3.403 × π / 4 = 2.673. For the full set of shapes and a calculator, see how to calculate steel weight and cost per foot.
Round and square bar chart
The last column uses a ton of 2,000 lb. Round and square bars are commonly stocked in 20 ft lengths, so the 20 ft columns give the weight of a full piece.
| Size | Round (lb/ft) | Square (lb/ft) | Round, 20 ft (lb) | Square, 20 ft (lb) | Round bar, feet per ton |
|---|---|---|---|---|---|
| 1/4 in | 0.167 | 0.213 | 3.34 | 4.25 | 11,974 |
| 5/16 in | 0.261 | 0.332 | 5.22 | 6.65 | 7,663 |
| 3/8 in | 0.376 | 0.479 | 7.52 | 9.57 | 5,322 |
| 1/2 in | 0.668 | 0.851 | 13.36 | 17.01 | 2,993 |
| 5/8 in | 1.044 | 1.329 | 20.88 | 26.58 | 1,916 |
| 3/4 in | 1.503 | 1.914 | 30.07 | 38.28 | 1,330 |
| 7/8 in | 2.046 | 2.605 | 40.92 | 52.11 | 977 |
| 1 in | 2.673 | 3.403 | 53.45 | 68.06 | 748 |
| 1-1/4 in | 4.176 | 5.317 | 83.52 | 106.34 | 479 |
| 1-1/2 in | 6.013 | 7.656 | 120.26 | 153.12 | 333 |
| 2 in | 10.690 | 13.611 | 213.80 | 272.22 | 187 |
| 2-1/2 in | 16.703 | 21.267 | 334.07 | 425.35 | 120 |
| 3 in | 24.053 | 30.625 | 481.06 | 612.50 | 83 |
Flat bar chart
Flat bar is listed by width and thickness. Read across for the width and down for the thickness.
| Thickness | 1 in | 1-1/2 in | 2 in | 3 in | 4 in | 6 in |
|---|---|---|---|---|---|---|
| 1/8 in | 0.43 | 0.64 | 0.85 | 1.28 | 1.70 | 2.55 |
| 3/16 in | 0.64 | 0.96 | 1.28 | 1.91 | 2.55 | 3.83 |
| 1/4 in | 0.85 | 1.28 | 1.70 | 2.55 | 3.40 | 5.10 |
| 3/8 in | 1.28 | 1.91 | 2.55 | 3.83 | 5.10 | 7.66 |
| 1/2 in | 1.70 | 2.55 | 3.40 | 5.10 | 6.81 | 10.21 |
| 5/8 in | 2.13 | 3.19 | 4.25 | 6.38 | 8.51 | 12.76 |
| 3/4 in | 2.55 | 3.83 | 5.10 | 7.66 | 10.21 | 15.31 |
| 1 in | 3.40 | 5.10 | 6.81 | 10.21 | 13.61 | 20.42 |
These are theoretical weights. Mills roll to tolerance, so a weighed bundle can differ by a percent or two. For a purchase, confirm with your supplier.
Worked example
A job needs twelve 4 × 1/2 in flat bars at 10 ft and six 1-1/4 in round bars at 20 ft.
- Flats: 3.403 × 4 × 0.5 = 6.81 lb/ft. Twelve at 10 ft is 120 ft, or 816.7 lb.
- Rounds: 2.673 × 1.25² = 4.18 lb/ft. Six at 20 ft is 120 ft, or 501.1 lb.
- Total: 1317.8 lb. At $0.55 per pound that is $724.77.
Converting to kg per metre
Multiply pounds per foot by 1.488 to get kilograms per metre. A 1 in round bar at 2.673 lb/ft is 3.98 kg/m, which matches the metric formula d² × 0.006165 with d = 25.4 mm. The reverse is to divide by 1.488.
Any size in the app
The chart lists common sizes. For anything else, open Bars or Flats in Steel Table USA, tap the control button and type your own size. Every property and the cost per foot update, and the weight uses 0.2836 lb per cubic inch, the same density as above. A 1/4 in round bar, for example, reads 0.17 lb/ft.
Questions people ask
How much does a 1 inch round steel bar weigh per foot?
About 2.67 pounds per foot. The formula is the diameter squared times 2.673, so 1 × 1 × 2.673 = 2.67. A 20 ft bar weighs about 53.5 lb.
How much does a 1 inch square steel bar weigh per foot?
About 3.40 pounds per foot, from side squared times 3.403.
How do I calculate the weight of a flat bar?
Multiply width in inches by thickness in inches by 3.403 to get pounds per foot. A 4 × 1/2 in flat is 6.81 lb/ft.
What density is used for steel bar weight?
The standard 490 lb per cubic foot, which is 7850 kg per cubic metre.
How many feet of bar are in a ton?
Divide 2,000 by the weight per foot. A 1 in round bar is 2.67 lb/ft, so a ton is about 748 ft.
Is this the same as rebar weight?
Rebar is numbered, not sized in inches, and its nominal weights are slightly different. See the rebar chart in the weight and cost guide.
Keep reading
Any bar size, instantly
Steel Table USA computes weight and cost for any bar, flat, plate or sheet size you type. Free on Google Play.
For reference, not for sign-off. Weights are theoretical, worked from a density of 490 lb per cubic foot, and prices are examples. Rolled shape weights are as shown in Steel Table USA from the AISC Shapes Database v16.0. Delivered weight differs slightly from theoretical weight because of rolling tolerances, so confirm quantities and prices with your supplier before ordering. The AISC Shapes Database is published by the American Institute of Steel Construction. Steel Table USA is an independent app and is not affiliated with or endorsed by AISC.