Building materials · Reference
US rebar is sized in eighths of an inch: a #4 bar is 0.500 in (12.7 mm) and weighs 0.668 lb/ft (0.996 kg/m) per ASTM A615. Canada uses metric 10M–35M bars; Europe uses EN 10080 Ø8–Ø32 mm.
Rebar is specified by nominal bar diameter; the rolled-in ribs (deformations) bond the bar to concrete. Bars ship in standard stock lengths.
| Bar size (soft-metric) | Nominal diameter | Cross-sectional area | Weight (lb/ft) | Mass (kg/m) |
|---|---|---|---|---|
| #3 (#10) | 0.375 in (9.5 mm) | 0.11 in² (71 mm²) | 0.376 | 0.561 |
| #4 (#13) | 0.500 in (12.7 mm) | 0.20 in² (129 mm²) | 0.668 | 0.996 |
| #5 (#16) | 0.625 in (15.9 mm) | 0.31 in² (200 mm²) | 1.043 | 1.556 |
| #6 (#19) | 0.750 in (19.1 mm) | 0.44 in² (284 mm²) | 1.502 | 2.240 |
| #7 (#22) | 0.875 in (22.2 mm) | 0.60 in² (387 mm²) | 2.044 | 3.049 |
| #8 (#25) | 1.000 in (25.4 mm) | 0.79 in² (509 mm²) | 2.670 | 3.982 |
| #9 (#29) | 1.128 in (28.7 mm) | 1.00 in² (645 mm²) | 3.400 | 5.071 |
| #10 (#32) | 1.270 in (32.3 mm) | 1.27 in² (819 mm²) | 4.303 | 6.418 |
| #11 (#36) | 1.410 in (35.8 mm) | 1.56 in² (1006 mm²) | 5.313 | 7.924 |
| #14 (#43) | 1.693 in (43.0 mm) | 2.25 in² (1452 mm²) | 7.650 | 11.410 |
| #18 (#57) | 2.257 in (57.3 mm) | 4.00 in² (2581 mm²) | 13.600 | 20.284 |
Source: ASTM A615 US rebar size chart (Concrete Calculate) (2026)
| Bar (CSA G30.18) | Nominal diameter | Cross-sectional area | Mass (kg/m) |
|---|---|---|---|
| 10M | 11.3 mm (0.44 in) | 100 mm² (0.155 in²) | 0.785 |
| 15M | 16.0 mm (0.63 in) | 200 mm² (0.310 in²) | 1.570 |
| 20M | 19.5 mm (0.77 in) | 300 mm² (0.465 in²) | 2.355 |
| 25M | 25.2 mm (0.99 in) | 500 mm² (0.775 in²) | 3.925 |
| 30M | 29.9 mm (1.18 in) | 700 mm² (1.085 in²) | 5.495 |
| 35M | 35.7 mm (1.41 in) | 1000 mm² (1.550 in²) | 7.850 |
Source: Reinforcing bar sizes — ASTM / CSA / BS-EN comparison (Reinforcing-Bar.com)
| Bar diameter | Cross-sectional area | Mass (kg/m) | Mass (lb/ft) |
|---|---|---|---|
| Ø8 mm (0.315 in) | 50.3 mm² (0.078 in²) | 0.395 | 0.265 |
| Ø10 mm (0.394 in) | 78.5 mm² (0.122 in²) | 0.617 | 0.415 |
| Ø12 mm (0.472 in) | 113 mm² (0.175 in²) | 0.888 | 0.597 |
| Ø16 mm (0.630 in) | 201 mm² (0.312 in²) | 1.579 | 1.061 |
| Ø20 mm (0.787 in) | 314 mm² (0.487 in²) | 2.467 | 1.658 |
| Ø25 mm (0.984 in) | 491 mm² (0.761 in²) | 3.855 | 2.591 |
| Ø32 mm (1.260 in) | 804 mm² (1.246 in²) | 6.316 | 4.244 |
Source: Reinforcing bar sizes — ASTM / CSA / BS-EN comparison (Reinforcing-Bar.com)
A spec table only helps if the buyer reads it. Many don't — shoppers routinely try to judge a product's size straight from the images, and wrong size or fit is the most-cited reason things get returned. The fix is to mark the real dimensions on the photo itself, where the buyer is already looking.
SizeMarker snaps dimension lines to the rebar (reinforcing bar)'s edges and exports at Amazon or Alibaba size, so the measurement is accurate and legible — not a guess typed over the picture. That answers the size question up front and cuts pre-sale questions and size-driven returns.
Related: Building material spec diagram maker · Product spec sheet maker · Best tools to add dimensions to product photos · Ecommerce returns & size statistics
A #4 bar has a nominal diameter of 0.500 in (12.7 mm), a cross-sectional area of 0.20 in² (129 mm²), and weighs 0.668 lb/ft (0.996 kg/m), per ASTM A615.
A #5 bar weighs 1.043 lb/ft (1.556 kg/m). It is 0.625 in (15.9 mm) in diameter with a 0.31 in² (200 mm²) cross-section (ASTM A615).
In ASTM soft-metric terms a #4 bar is designated #13 (13 mm). The nearest Canadian CSA bar is 15M (16.0 mm, 200 mm²) and the nearest European EN 10080 sizes are Ø12–Ø16 mm.
10M = 11.3 mm dia, 100 mm², 0.785 kg/m; 15M = 16.0 mm, 200 mm², 1.570 kg/m; 20M = 19.5 mm, 300 mm², 2.355 kg/m, per CSA G30.18.
North American rebar is commonly stocked in 20, 40 and 60 ft lengths (40 ft is a typical mill length); European practice uses 12 m bars. Rebar is cut and bent to the schedule.
Every figure on this page is traced to a named source, linked under each table. Standard sizes come from published standards and established industry references; where a size is a typical range or varies by manufacturer, we say so. Sizes vary by region, model and revision — treat these as the standard reference, and confirm the exact spec of the item you are selling.
Mark accurate dimensions and specs on your product photos in minutes. Free to start.
Start free · 30 credits on sign-up