How Much Does Rebar Weigh?
Rebar weight is its length times a per-foot or per-metre figure that depends on the bar size. Here are the weights for every common bar, the simple formula behind them, and how to turn your total length into a weight to price.
By the Calculate My Reno Team / Published
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Rebar weight is simple: it is the total length (your linear feet, with laps and waste) times a weight per foot or per metre that depends on the bar size. The bigger the bar, the more it weighs per foot, because the weight scales with the diameter squared. If “linear feet” or “lap” is new, the rebar glossary has the plain-English version.
Skip the math
The rebar calculator multiplies your total length - including lap splices and waste - by the weight for the bar you pick, so you get the weight to order without touching a chart. This guide is the reference behind it.
The formula
weight = total length × weight per unit length
metric: weight per metre (kg/m) ≈ 0.00617 × (diameter in mm)²
The 0.00617 constant comes from steel at 7,850 kg/m³ - it is the same as the widely used d²/162 rule. US #-bar weights are the ASTM A615 nominal figures. Canadian M-bars are sized by area, so their weight is the nominal area in mm² × 0.00785.
Rebar weight per foot and per metre
| Bar | Diameter | Weight (lb/ft) | Weight (kg/m) | 20 ft stick |
|---|---|---|---|---|
| #3 | 3/8 in (9.5 mm) | 0.376 | 0.560 | 7.5 lb |
| #4 | 1/2 in (12.7 mm) | 0.668 | 0.994 | 13.4 lb |
| #5 | 5/8 in (15.9 mm) | 1.043 | 1.552 | 20.9 lb |
| #6 | 3/4 in (19.1 mm) | 1.502 | 2.235 | 30.0 lb |
| #7 | 7/8 in (22.2 mm) | 2.044 | 3.042 | 40.9 lb |
| #8 | 1 in (25.4 mm) | 2.670 | 3.973 | 53.4 lb |
Metric bars (6 m stick): 10 mm = 0.617 kg/m (3.7 kg), 12 mm = 0.888 kg/m (5.3 kg), 16 mm = 1.578 kg/m (9.5 kg), 20 mm = 2.466 kg/m (14.8 kg).
Worked example
250 m of 12 mm bar (a small slab mat with waste):
- Weight per metre: 0.00617 × 12² = 0.888 kg/m.
- Total weight: 250 × 0.888 = 222 kg (about 0.22 tonne).
For the full size reference see the rebar size chart; to work out the length in the first place see how much rebar do I need.
Using the weight
- Pricing - rebar is sold per ton or tonne, so convert your length to weight to compare quotes.
- Handling - the weight tells you what each bundle weighs to lift and move.
- Order on the length with laps and waste, not the bare grid length, or the weight will come up short.
Frequently asked questions
How much does #4 rebar weigh?
A #4 bar weighs 0.668 lb/ft (0.994 kg/m), so a 20 ft stick is about 13.4 lb. A #3 is 0.376 lb/ft, a #5 is 1.043 lb/ft and a #6 is 1.502 lb/ft. Multiply the weight per foot by your total linear feet (including laps and waste) to get the weight to order.
How much does a 20 ft stick of rebar weigh?
Multiply the per-foot weight by 20: a #3 is about 7.5 lb, a #4 about 13.4 lb, a #5 about 20.9 lb and a #6 about 30 lb. A 6 m metric bar is 6 times the per-metre weight, so a 12 mm bar is about 5.3 kg and a 16 mm about 9.5 kg.
How do you calculate rebar weight?
Weight = total length × weight per unit length for the bar size. For metric bars the weight per metre is about 0.00617 × (diameter in mm)², which is the d²/162 rule, from steel at 7,850 kg/m³. So 250 m of 12 mm bar is 250 × 0.888 = 222 kg. The calculator multiplies your total length (with laps and waste) by the right figure automatically.
How much does rebar weigh per foot?
By bar size: #3 = 0.376 lb/ft, #4 = 0.668, #5 = 1.043, #6 = 1.502, #7 = 2.044 and #8 = 2.670 lb/ft. In metric, 10 mm = 0.617 kg/m, 12 mm = 0.888, 16 mm = 1.578 and 20 mm = 2.466 kg/m. The bigger the bar, the faster the weight climbs, because it scales with the diameter squared.
Why is rebar sold by weight?
Rebar is priced by weight - per ton or per tonne - because that is how steel is made and traded, even though you buy it as bars of a set length. Working out the total weight from your length lets you compare a price per ton against a price per bar, and tells you what you are lifting and transporting.