Rebar Weight Calculator
A rebar weight calculator multiplies pounds per foot by total length: 100 ft of #4 bar at 0.668 lb/ft weighs 66.80 lb, and #5 weighs 1.043 lb/ft.
How to calculate rebar weight
A rebar weight calculator turns a bar size and a total length into pounds. Pick the bar number and type the total length in feet. The tool looks up the weight per foot for that size and multiplies.
You need the weight to price the order, to plan how many trips the truck makes, and to see if you can carry it yourself. Steel is dense, so rebar weighs more than it looks like it should.
The formula in plain words
- Look up the weight per foot for the bar size.
- Multiply the weight per foot by the total feet.
That is all. The tool stores the standard weights for sizes #3 through #11.
Worked example: a run of #4 bar
A footing needs 100 ft of #4 bar.
- Weight per foot: 0.668 lb
- Total: 0.668 × 100 = 66.80 lb
Worked example: a slab grid
A 20 ft by 20 ft slab has #5 bars every 12 in in both directions.
- Bars per direction: 20 ÷ 1 + 1 = 21 bars
- Total length: 21 bars × 20 ft × 2 directions = 840 ft
- Weight per foot of #5: 1.043 lb
- Total: 1.043 × 840 = 876.12 lb
That ignores cover from the edges, laps, and any cut waste. Treat it as a minimum, then add what the plans or your supplier recommend.
Rebar weight by size
| Bar size | Nominal diameter | Weight per foot |
|---|---|---|
| #3 | 3/8 in | 0.376 lb |
| #4 | 1/2 in | 0.668 lb |
| #5 | 5/8 in | 1.043 lb |
| #6 | 3/4 in | 1.502 lb |
| #7 | 7/8 in | 2.044 lb |
| #8 | 1 in | 2.670 lb |
| #9 | 1 1/8 in | 3.400 lb |
| #10 | 1 1/4 in | 4.303 lb |
| #11 | 1 3/8 in | 5.313 lb |
Weight climbs quickly. A #8 bar weighs about four times as much per foot as a #4.
How to get your total length
Count the bars of each size and multiply by the length of each. Do this on your plans for every size. Run the calculator once per size and add the weights.
For a grid, count the bars in each direction. The number of bars is the length of the slab divided by the spacing, plus one. For footings, take the footing’s length and the number of continuous bars.
Rebar is commonly sold in 20 ft lengths, and the supplier can often cut it to size. Ask them what they stock before you finalize your plan.
Using the weight
Reinforcing steel is often priced by the pound or by the hundredweight. Multiply your total pounds by the price. Check if delivery is extra and whether the quoted price is for straight or bent bar.
For hauling, check your vehicle’s payload. 876 lb of rebar is a heavy load for a small trailer, and long bars overhanging a truck bed need flags and proper tie-down.
Common mistakes
- Forgetting the lap. Bars overlap where they join, so you need more than the plan’s net length.
- Mixing up bar numbers and diameters. #4 is a half inch, not 4 inches.
- Leaving out stirrups, hooks, and bent shapes. They count as length too.
- Treating this as a structural design. Size, spacing, and cover for foundations and slabs that carry load come from the code or an engineer.
- Not allowing for cutoffs. Offcuts that are too short to use are still material you buy.
Related calculators
To find the concrete that goes around the steel, the concrete weight calculator helps with loads and handling. The footing size calculator sizes the footing, and the sonotube calculator covers round piers.
Frequently asked questions
How much does rebar weigh per foot?
It depends on bar size. #3 weighs 0.376 lb/ft, #4 weighs 0.668, #5 weighs 1.043, #6 weighs 1.502, #7 weighs 2.044, #8 weighs 2.670, #9 weighs 3.400, #10 weighs 4.303, and #11 weighs 5.313.
What does the bar number mean?
The number is the bar's diameter in eighths of an inch. A #4 bar is 4/8 in, or half an inch, in nominal diameter. A #8 bar is 8/8 in, or 1 in.
How do I calculate rebar weight?
Multiply the bar's weight per foot by the total length of that bar size. For 100 ft of #4, that is 0.668 × 100 = 66.80 lb.
Does the calculator include laps and bends?
No. It multiplies the length you enter. Add extra for overlaps where bars are spliced and for hooks or bends in the bar lengths. An engineer's drawings or the local code set the lap length.
What if I enter a bar size outside 3 to 11?
The tool keeps the size between #3 and #11 and rounds to the nearest whole number. Smaller wire and larger bars need another chart.
Estimates only. Verify quantities with your supplier before purchasing.