Rebar weight chart

kg/m = d² ÷ 162 · lb/ft = 2.67 × d²

Weight of reinforcing steel bars per foot and per metre. For metric bars, weight in kg/m = d² / 162 with d in mm; for US bars the bar number is the diameter in eighths of an inch.

A worker tying steel reinforcing bars for a concrete floor — Photo: Bill Dowell, Wikimedia Commons, public domain.

US rebar sizes (ASTM A615)

Bar	Diameter (in)	Diameter (mm)	lb/ft	kg/m	20 ft bar (lb)
#3 rebar	0.375	9.5	0.376	0.560	7.5
#4 rebar	0.5	12.7	0.668	0.994	13.4
#5 rebar	0.625	15.9	1.043	1.552	20.9
#6 rebar	0.75	19	1.502	2.235	30.0
#7 rebar	0.875	22.2	2.044	3.042	40.9
#8 rebar	1	25.4	2.670	3.973	53.4
#9 rebar	1.128	28.7	3.400	5.060	68.0
#10 rebar	1.27	32.3	4.303	6.404	86.1
#11 rebar	1.41	35.8	5.313	7.907	106.3
#14 rebar	1.693	43	7.650	11.384	153.0
#18 rebar	2.257	57.3	13.600	20.239	272.0

Metric rebar and TMT bars

Bar	Area (mm²)	kg/m	12 m bar (kg)	Bars per tonne (12 m)
6 mm rebar	28.3	0.222	2.66	375.4
8 mm rebar	50.3	0.395	4.74	211.0
10 mm rebar	78.5	0.617	7.40	135.1
12 mm rebar	113	0.888	10.66	93.8
14 mm rebar	154	1.210	14.52	68.9
16 mm rebar	201	1.580	18.96	52.7
20 mm rebar	314	2.470	29.64	33.7
25 mm rebar	491	3.850	46.20	21.6
28 mm rebar	616	4.830	57.96	17.3
32 mm rebar	804	6.310	75.72	13.2
40 mm rebar	1257	9.860	118.32	8.5
50 mm rebar	1963	15.400	184.80	5.4

Why d² / 162?

A round bar of diameter d mm has an area of π d² / 4 mm². One metre of it is π d² / 4 × 10⁻⁶ m³, and at 7850 kg/m³ that is 0.006165 × d² kg, which is d² / 162.2. Rounded to d² / 162, it is accurate to about 0.1 %.

In US units the same rule is lb/ft = 2.67 × d² with d in inches. Because the US bar number is the diameter in eighths of an inch, it also works as lb/ft ≈ bar number² × 0.0417: #4 gives 16 × 0.0417 = 0.668 lb/ft.

Worked example: 100 bars of 16 mm, each 12 m long. Weight per metre = 16² ÷ 162 = 256 ÷ 162 = 1.580 kg/m; one bar = 1.580 × 12 = 18.96 kg; total = 1896 kg, about 1.9 tonnes. The rebar weight formula guide shows where 162 comes from and how accurate it is.

Rebar per square metre of slab or wall

Weight of one layer of bars in one direction, in kg per m², for common bar sizes and spacings (centre to centre). For a mesh with bars both ways, add the two directions; then allow for laps, hooks and chairs, typically 5 to 10 % on top.

Bar	@ 100 mm	@ 125 mm	@ 150 mm	@ 200 mm	@ 250 mm	@ 300 mm
8 mm rebar	3.95	3.16	2.63	1.98	1.58	1.32
10 mm rebar	6.17	4.94	4.11	3.09	2.47	2.06
12 mm rebar	8.88	7.10	5.92	4.44	3.55	2.96
16 mm rebar	15.80	12.64	10.53	7.90	6.32	5.27
20 mm rebar	24.70	19.76	16.47	12.35	9.88	8.23

US bar sizes and metric equivalents

US bars are also designated in "soft metric" sizes (#4 is No. 13), which name the same bar in millimetres. The nearest metric bar in the last columns is a different product, useful when converting a design between unit systems.

US bar	Soft metric	Diameter (mm)	kg/m	Nearest metric bar	kg/m
#3 rebar	No.10	9.5	0.560	10 mm rebar	0.617
#4 rebar	No.13	12.7	0.994	12 mm rebar	0.888
#5 rebar	No.16	15.9	1.552	16 mm rebar	1.580
#6 rebar	No.19	19	2.235	20 mm rebar	2.470
#7 rebar	No.22	22.2	3.042	20 mm rebar	2.470
#8 rebar	No.25	25.4	3.973	25 mm rebar	3.850
#9 rebar	No.29	28.7	5.060	28 mm rebar	4.830
#10 rebar	No.32	32.3	6.404	32 mm rebar	6.310
#11 rebar	No.36	35.8	7.907	32 mm rebar	6.310
#14 rebar	No.43	43	11.384	40 mm rebar	9.860
#18 rebar	No.57	57.3	20.239	50 mm rebar	15.400

Standard bar lengths

Metric rebar and TMT bars are usually supplied in 12 m lengths (sometimes 6 m or 9 m), and bars of 8 mm and less also in coils. In the US, bars are stocked in 20 ft, 40 ft and 60 ft lengths. Order quantities are normally in tonnes or tons, so the "bars per tonne" column above helps check a delivery.

Frequently asked questions

What is the weight of 12 mm rebar per metre?

0.888 kg/m (144 ÷ 162 = 0.889). A 12 m bar weighs about 10.66 kg, and a tonne is about 94 bars of 12 m.

How much does #4 rebar weigh?

#4 rebar (1/2 in diameter) weighs 0.668 lb/ft, so a 20 ft bar is about 13.4 lb and a 40 ft bar about 26.7 lb.

What is the formula for rebar weight?

Metric: kg/m = d² ÷ 162 with the diameter d in mm. US: lb/ft = 2.67 × d² with d in inches, or bar number² × 0.0417. Both come from the area of the bar times 7850 kg/m³ (490 lb/ft³).

How many 12 m bars of 10 mm rebar are in a tonne?

A 10 mm bar weighs 0.617 kg/m, so one 12 m bar is 7.40 kg and a tonne holds about 135 bars.

Do ribs or deformations change the weight?

No. Deformed bars and TMT bars are specified by nominal diameter and nominal mass per metre; the ribs are accounted for in the nominal size. Standards allow a few percent of mass tolerance per bar.

How much rebar is needed per square metre of slab?

For one layer, divide the weight per metre by the spacing in metres: 10 mm bars at 150 mm centres give 0.617 ÷ 0.15 = 4.11 kg/m² in one direction. Double it for bars in both directions, and add laps and chairs.

Other weight charts

US bar data adapted from Wikipedia, "Rebar" (CC BY-SA 4.0). Metric masses are nominal values; Indian TMT bars follow IS 1786 with the same nominal masses.