How Much Does Rebar Weight per Foot?

Rebar is steel reinforcing bar used to increase the tensile strength of brick, block, and concrete construction so it can better resist cracking. It helps strengthen and stabilize walls, floors, foundations, and even ceilings. Rebar weight per foot is determined by its diameter and affects its strength and uses.

The weight of rebar depends on its type and nominal diameter. Common sizes and weights of carbon steel rebar used in low-density residential construction are #3 (3/8” dia.) at 0.376lb/ft, #4 (1/2” dia.) at 0.668lb/ft, and #5 (5/8” dia.) at 1.043lb/ft. The greater the diameter and weight, the more tensile strength it provides to concrete and other masonry structures.

In this guide, we’ll discuss how much carbon steel rebar weighs per foot and its different sizes, plus provide a weight chart for easier identification. We’ll explain how to find the weight of rebar, how to calculate it and provide a link to a rebar weight calculator. Our aim is to provide the information you need for your concrete project.

How Much Does Rebar Weight per Foot

Hot-rolled carbon steel or tempered steel rebar is the least expensive rebar option. It is also the most common choice for reinforcing concrete used in low-density housing and commercial construction.

To help concrete better grip and bond to the metal, rebar usually has a raised pattern molded into its surface. The pattern of ribs, ridges, crescents, indentations, knots, or lugs may spiral around the rod, form herringbone-like steps from end to end or run longitudinally along the rebar’s length.

The weight of the rebar depends on its diameter and length. A linear foot of #2 or 1/4″ diameter rebar weighs 0.167 lbs., #3 or 3/8” weighs 0.376 lbs., and #4 or 1/2″ rebar weighs 0.688 lbs.

Multiplying the weight per foot of a specific diameter identifies the weight of the length. So, an 8-foot piece of #4 rebar will weigh 5.504 pounds, and a 20-foot length 13.76 pounds. The greater the diameter and length, the greater the weight.

Reinforcing Bar Sizes

The diameter of the rebar typically determines its weight, strength, and use parameters. The actual diameter is measured to include all raised deformations, while the nominal diameter refers to the cross-sectional bar diameter without the deformities.

Rebar in the United States has a number (#) reference which identifies its nominal diameter. The number value identifies how many 1/8” units thick the rebar is nominally, so #4 rebar is (4 x 1/8” = 4/8” = 1/2″) a half-inch thick in diameter.

The thickness of rebar in Canada is measured in millimeters, so has a metric reference number system to identify its nominal diameter. The size of the rebar is based on the nominal diameter of the rebar in millimeters (mm), rounded to the nearest 5. A capital ‘M’ is used to denote mm, so 10M rebar is 11.3mm in diameter, 15M is 16.0mm, and 20M is 19.5mm.

It should be noted, though, that rebar manufactured with the US identification also has a ‘soft’ metric size based on its conversion from inches to millimeters. So, a US #2, which is 1/4″ in diameter, becomes a #6 by rounding the 6.35mm to the nearest whole number.

Likewise, the 1/2″ #4 becomes a #13 based on its 12.7mm diameter. Rebar manufactured in Europe has a marking more reflective of its nominal diameter in whole millimeters – 6mm diameter rebar is 6,0 and 14mm diameter is identified as 14,0.

To help identify the rebar’s nominal diameter or size, check the steel’s side for markings. US (ASTM markings) steel usually has a combination of three or four letters, numbers, or symbols sequentially spaced within the deformation pattern. The first letter or symbol, read top to bottom, identifies the producing mill, and the next number is the bar size.

The next two symbols identify the type and grade of the steel. Canadian (CSA markings) steel has similar markings, also read top down, but the size can occupy two spaces within the pattern and has a blank space separating the grade reference, which can take 3 or 4 spaces.

It should be noted that even different mills may stamp the steel differently. If you’re confused and unsure if the steel is in inches or metric, take heart that the difference is noticeable. Since ‘10’ in inches means a diameter of 1.270”, which is significantly different from ‘10’ in metric which means 10mm or 3/8” diameter.

Rebar Weight Chart

Reinforcing steel bars or rebar is manufactured to meet the building standards and codes of the country in which it is typically used or shipped to. So, #4 rebar anywhere in the U.S.A. will have the same weight per foot and nominal diameter. The tables below identify common rebar sizes for the U.S.A. and Canada.

Common U.S. Rebar Sizes
Bar Size		Nominal Diameter			Mass per Unit Length
U.S. Size	‘Soft’ Metric Size	Inches		Millimeter	Lb/ft	Kg/ft	Kg/m
#2	#6	0.250	1/4	6.35	0.167	0.0757	0.249
#3	#10	0.375	3/8	9.525	0.376	0.1707	0.561
#4	#13	0.500	1/2	12.70	0.668	0.3033	0.996
#5	#16	0.625	5/8	15.875	1.043	0.4735	1.556
#6	#19	0.750	3/4	19.05	1.502	0.6819	2.240
#7	#22	0.875	7/8	22.225	2.044	0.9279	3.049
#8	#25	1.000	1	25.40	2.670	1.2122	3.982
#9	#29	1.128	1-1/8	28.65	3.400	1.5436	5.071
#10	#32	1.270	1-1/4	32.26	4.303	1.9536	6.418
#11	#36	1.410	1-1/2	35.81	5.313	2.4121	7.924
#14	#43	1.693	1-3/4	43.0	7.650	3.4731	11.410
#18	#57	2.257	2-1/4	57.30	13.600	6.1744	20.284

* Fractional inches are rounded to the nearest eighth.

Common Canadian Rebar Sizes
Canadian Size	Nominal Diameter			Mass per Unit Length
	Millimeter	Inches		Kg/m	Kg/ft	Lb/ft
10M	11.3	0.445	3/8	0.785	0.2393	0.527
12M	12.7	0.500	1/2	0.889	0.2710	0.597
15M	16.0	0.625	5/8	1.570	0.4796	1.054
20M	19.5	0.750	3/4	2.355	0.7096	1.563
25M	25.2	1.000	1	3.925	1.1831	2.606
30M	29.9	1.196	1-1/4	5.495	1.6566	3.649
35M	35.7	1.410	1-1/2	7.850	2.3667	5.213
45M	43.7	1.750	1-3/4	11.775	3.5503	7.820
55M	56.4	2.256	2-1/4	19.625	5.9174	13.034

* The “M” represents millimeters (mm) and fractional inches are rounded to the nearest eighth.

How to Find Weight of Rebar

Finding out the weight of rebar can be done in a number of ways, provided you know the size of its nominal diameter. If you don’t know the size, check the steel for markings. For US (ASTM markings) steel, the first letter or symbol, read top down, identifies the producing mill, and the next number is the bar size.

For Canadian (CSA markings) steel, the top mark is also the manufacturer and the next is the size. However, the size may be in one space or occupy two spaces, separated by a blank space before the next identifying mark.

Once you’ve determined the size, use the charts above to identify the weight per foot or meter. Multiplying the length of the rebar by its unit weight per measure will give the weight for that length of rebar.

For example, a foot of #4 rebar has a unit weight of 0.668lb/ft, so an 8ft length will weigh (8ft x 0.668lb/ft) 5.344 pounds. A 20ft length would weigh (20 x 0.668lb/ft) 13.36 pounds.

Another method is to use an online calculator to determine the rebar weight. Just input the size value and length, press ‘Calculate’ if necessary, and the calculation is done for you. Alternatively, use a formula.

How to Calculate a Rebar Weight

Calculating rebar weight can be done using the unit weight of the bar size as found in the Tables above, and multiplying it by the length of the rebar. Alternative methods include using an online rebar weight calculator and following its instructions, or using a formula.

• Using Tables, identify the bar size and select the appropriate weight per unit, and multiply by the length of that size.
  i.e.: #6 rebar weighs 1.502lb/ft, 0.6819kg/ft, or 2.240kg/m. So, multiplying the length of rebar by any of those values will provide the rebar weight.

• An online calculator is straightforward and usually only requires the size of the rebar, its length, and the number of pieces.
• Formulas can be more challenging and can lead to errors. If calculating steel weight per meter in kg use the following formula:
  steel weight =(Diameter)²/162.28×Length or W =(D)² L/162.28 kg
  Note: the result is the weight in kilograms per meter

• If calculating steel weight per foot in kg use the following formula:
  steel weight =(Diameter)²/533×Length or W =(D)² L/533 kg
  Note: the result is weight in kilograms per foot

To convert the weight to pounds, multiply the kilogram value by 2.2046.

Rebar Weight Calculator

There are numerous online rebar weight calculators available. Some are more complex and others are very straightforward. Our preferred calculator requires that the unit of length and rebar size be selected from drop-down menus and that the user input the length and quantity before clicking on ‘Calculate’.

For example, the footings of a 20’ x 30’ shed typically require two strands of #4 or 1/2” rebar with an overlap of at least two feet at all joints. The total length of the footing is 100ft (20+30+20+30).

If using 20-foot lengths of rebar, that would be 5 lengths per stand, or 10 lengths total. However, each strand would require six 2ft overlaps, so you’re better off using 6 lengths of 20-foot rebar per strand and having longer overlaps, thus requiring 12 lengths in total.

Input 20 in the ‘Length’, select the ‘ft’ unit, input 12 for the ‘Quantity’, select ‘4’ for the rebar size, and click on ‘Calculate’. The ‘Results’ identify the ‘Weight’ as 160.8lbs and 0.1 tons, ‘Total Length’ as 240 feet, and ‘Pounds per Foot’ as 0.67lbs.

The total weight could easily be managed, but unless you have a long trailer or flatbed truck, you’ll probably want it delivered to the work site.

Conclusion

Rebar is used for improving the tensile strength of concrete and masonry structures. The steel grade, size, spacing, and location within each structural element determine how the rebar will strengthen the structure. Carbon steel rebar is typically used in low-density residential construction, with #3, #4, and #5 rebar diameters being the most common.

The numbers represent how many 1/8” units the nominal diameter is, and affects how much it weighs. #3 (3/8” dia.) weighs 0.376lb/ft, #4 (4/8 or 1/2” dia.) is 0.668lb/ft, and #5 (5/8” dia.) is 1.043lb/ft. Larger diameters weigh more per foot, and offer greater tensile strength, but cost more, so aren’t often used in low-density structures.

Hopefully, you have a better understanding of how much rebar weighs and how to determine its weight.