Rebar Weight Calculator
Calculate steel reinforcement bar weights for construction projects. Get accurate weights for all standard rebar sizes from #3 to #18.
Calculate Rebar Weight
Standard Rebar Size Chart
| Size | Diameter (mm) | Diameter (in) | Weight (kg/m) | Weight (lbs/ft) | Area (mm²) |
|---|---|---|---|---|---|
| #3 | 9.5 | 0.375 | 0.560 | 0.376 | 71 |
| #4 | 12.7 | 0.5 | 0.994 | 0.668 | 129 |
| #5 | 15.9 | 0.625 | 1.552 | 1.043 | 199 |
| #6 | 19.1 | 0.75 | 2.235 | 1.502 | 284 |
| #7 | 22.2 | 0.875 | 3.042 | 2.044 | 387 |
| #8 | 25.4 | 1 | 3.973 | 2.670 | 510 |
| #9 | 28.7 | 1.128 | 5.060 | 3.400 | 645 |
| #10 | 32.3 | 1.27 | 6.404 | 4.303 | 819 |
| #11 | 35.8 | 1.41 | 7.907 | 5.313 | 1006 |
| #14 | 43 | 1.693 | 11.384 | 7.650 | 1452 |
| #18 | 57.3 | 2.257 | 20.238 | 13.600 | 2581 |
How Rebar Weight is Calculated
Rebar weight is calculated based on the diameter and length of the steel bar, using the standard density of steel (7850 kg/m³).
Weight Formula
Weight (kg/m) = (D² / 162) where D is diameter in mm
Weight (lbs/ft) = (D² / 600) where D is diameter in inches
Rebar Size Designation
In the US, rebar sizes are designated by numbers (#3, #4, #5, etc.). The number represents the bar diameter in eighths of an inch. For example, #8 rebar has a diameter of 8/8 = 1 inch (25.4mm).
Common Rebar Sizes
- #3 and #4: Light-duty residential work, small slabs
- #5 and #6: Standard residential and commercial slabs, driveways
- #7 and #8: Heavy structural work, columns, beams
- #9 to #11: Major structural elements, bridges
- #14 and #18: Extra heavy structural applications, massive concrete work
Pro Tips for Rebar Selection
Order Extra Material
Always order 5-10% extra rebar to account for cutting waste, overlaps, and potential mistakes during installation.
Standard Bar Lengths
Rebar typically comes in 20-foot (6m) or 40-foot (12m) lengths. Plan your cuts to minimize waste.
Spacing Requirements
Common rebar spacing is 12″ (305mm) on center for slabs. Check local building codes for specific requirements.
Lap Lengths
When splicing rebar, overlap bars by at least 40 times the bar diameter for proper structural integrity.
Concrete Cover
Maintain minimum 2″ (50mm) concrete cover over rebar for exterior work, 1.5″ (38mm) for interior work.
Grade Selection
Grade 60 (420 MPa) is most common for general construction. Grade 40 (280 MPa) may be used for lighter applications.
Frequently Asked Questions
How much does #8 rebar weigh per foot?
#8 rebar weighs 2.670 pounds per foot (lbs/ft) or 3.973 kilograms per meter (kg/m). This is the most commonly used size for heavy structural work.
What size rebar should I use for a concrete slab?
For residential slabs and driveways, #4 or #5 rebar is typically sufficient. For heavier-duty applications like commercial floors, use #5 or #6 rebar. Always consult local building codes and a structural engineer for specific requirements.
How is rebar weight calculated from diameter?
Rebar weight is calculated using the formula: Weight (kg/m) = (D² / 162), where D is the diameter in millimeters. For imperial units: Weight (lbs/ft) = (D² / 600), where D is in inches. This is based on steel's density of 7850 kg/m³.
What is the difference between #3 and #4 rebar?
#3 rebar has a diameter of 3/8″ (9.5mm) and weighs 0.376 lbs/ft, while #4 rebar has a diameter of 1/2″ (12.7mm) and weighs 0.668 lbs/ft. #4 rebar is stronger and more commonly used for residential concrete slabs.
How many pieces of rebar are in a ton?
The number of bars per ton depends on the rebar size and length. For example, a 20-foot #5 bar weighs about 20.86 lbs, so there are approximately 96 bars per ton (2000 lbs). For #8 rebar at 20 feet (53.4 lbs per bar), there are about 37 bars per ton.
Can I use metric rebar sizes in the US?
While US construction primarily uses imperial measurements (#3, #4, etc.), metric rebar is used in many countries. The calculator provides both metric (kg/m, mm) and imperial (lbs/ft, inches) measurements for convenience. Always verify local code requirements.
What is the standard length of rebar?
Standard rebar lengths are typically 20 feet (6 meters) or 40 feet (12 meters) in the US. Some suppliers also offer 60-foot lengths. Custom lengths may be available upon request, but standard lengths are most economical.
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