Standard stock lengths, what a full bar weighs, and why the stock length decides your order
← Back to the calculatorWhat that means in weight: a full 20 ft #4 bar is 13.4 lb, a 40 ft #4 bar is 26.7 lb. Any line longer than the stock bar is two bars joined by a lap — a 24 ft line on 20 ft stock is two bars and one 20 in lap, and the same line on 40 ft stock is one bar with no lap at all.
Rebar is not cut to your line length at the mill — it is rolled to a small number of stock lengths that the whole supply chain agrees on, and your takeoff has to end in one of them. Which lengths those are depends on where you are buying:
| Region | Standard stock | Also seen | Full bar, in the other unit |
|---|---|---|---|
| United States | 20 ft, 40 ft | 60 ft (special order) | 20 ft = 6.10 m · 40 ft = 12.19 m |
| Canada / UK / EU / AU | 12 m | 6 m | 12 m = 39 ft 4 in · 6 m = 19 ft 8 in |
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The reasons are the same everywhere: transport and handling. A 20 ft bar rides a standard flatbed without permits, two at a time on a forklift, and cuts cleanly into the short lines a residential grid needs. The 40 ft length comes from mill rolling and rail limits, and it halves the number of laps on long lines. 60 ft exists in the US, but it needs a longer truck, and many yards treat it as a special order with a lead time.
Two habits keep this honest. Ask your yard which lengths it actually stocks before the takeoff, not after — the choice changes the order, as the tables below show. And when a drawing spec says “bar schedule” with cut lengths, remember those are the lengths to place, not the lengths to buy; the yard still ships stock lengths.
A stock bar weighs its unit weight times its length. These are the nominal ASTM A615 / A706 values for deformed bar — the same numbers as the size and diameter chart, arranged for ordering:
| Bar | lb/ft | 20 ft bar (lb) | 40 ft bar (lb) | kg/m |
|---|---|---|---|---|
| #3 | 0.376 | 7.5 | 15.0 | 0.560 |
| #4 | 0.668 | 13.4 | 26.7 | 0.994 |
| #5 | 1.043 | 20.9 | 41.7 | 1.552 |
| #6 | 1.502 | 30.0 | 60.1 | 2.235 |
| #7 | 2.044 | 40.9 | 81.8 | 3.042 |
| #8 | 2.670 | 53.4 | 106.8 | 3.973 |
| #9 | 3.400 | 68.0 | 136.0 | 5.060 |
| #10 | 4.303 | 86.1 | 172.1 | 6.404 |
| #11 | 5.313 | 106.3 | 212.5 | 7.907 |
| #14 | 7.650 | 153.0 | 306.0 | 11.384 |
| 18 | 13.600 | 272.0 | 544.0 | 20.239 |
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The handling number hides in the same table: a #4 bar is a one-person lift at either length, and a single #18 40 ft bar is 544 lb — equipment territory. That is the other reason 20 ft is the workhorse length on small jobs. And the weights themselves are nominal ASTM values — what the bar number measures, and how to verify a stick on a scale, is on the rebar measurement page.
Every bar in your grid is a line of a certain length, and it is cut from a stock bar. If the line fits inside one stock bar, it is one bar and zero laps. If it does not, it is two bars and one lap splice — and the lap is steel you buy and never see again as length:
| Line length | On 20 ft stock | Laps needed | On 40 ft stock | Laps needed |
|---|---|---|---|---|
| 10 ft | 1 bar | 0 | 1 bar | 0 |
| 16 ft | 1 bar | 0 | 1 bar | 0 |
| 20 ft | 1 bar | 0 | 1 bar | 0 |
| 24 ft | 2 bars | 1 | 1 bar | 0 |
| 30 ft | 2 bars | 1 | 1 bar | 0 |
| 40 ft | 2 bars | 1 | 1 bar | 0 |
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How long is a lap? The field rule of thumb is 40 × the bar diameter, never less than 12 in: #3 = 15 in, #4 = 20 in, #5 = 25 in, #6 = 30 in, #8 = 40 in. It is a rule of thumb only — ACI 318 sets the required splice by bar size, concrete strength, cover and spacing, and the drawings govern. The development length page carries the full Class A vs Class B table by bar size.
Offcut is not a percentage — it is the remainder left on each stock bar after the pieces are cut. And a remainder cannot be joined into a line: two 6 ft pieces from two different bars do not make a 12 ft line, they make scrap. So the pieces-per-bar rule is floor(stock ÷ line), and the waste on a job depends entirely on how your line lengths divide into the stock length.
Twenty 7 ft lines — 140 ft of steel to place, whichever bar you buy — run on the three stocks:
| Stock bar | Pieces per bar | Bars to buy | Length bought | Offcut | Waste |
|---|---|---|---|---|---|
| 20 ft | 2 | 10 | 200 ft | 60 ft | 30.0% |
| 30 ft | 4 | 5 | 150 ft | 10 ft | 6.7% |
| 40 ft | 5 | 4 | 160 ft | 20 ft | 12.5% |
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One takeoff, between 6.7% and 30.0% waste — decided only by the stock length. Note that the longest bar is not automatically the best: 30 ft wins here because 7 ft divides into it more cleanly, not because it is bigger. Before ordering, look down the whole takeoff for short lines that fit inside the leftovers — an offcut that becomes a line is the cheapest saving on the job. The rebar estimator page works this through line by line, and its takeoff table is the written form of the same arithmetic.
Three vocabularies describe the same steel, and the stock length is what converts between them. The yard sells whole bars; the quote arrives in pounds or tons. The bridge is the weight of a full bar:
| Bar | 20 ft bars per short ton | 40 ft bars per short ton | Linear ft per ton, 40 ft |
|---|---|---|---|
| #3 | 265 | 132 | 5,310 |
| #4 | 149 | 74 | 2,995 |
| #5 | 95 | 47 | 1,916 |
| #6 | 66 | 33 | 1,331 |
| #7 | 48 | 24 | 979 |
| #8 | 37 | 18 | 748 |
| #9 | 29 | 14 | 588 |
| #10 | 23 | 11 | 466 |
| #11 | 18 | 9 | 377 |
| #14 | 13 | 6 | 261 |
| #18 | 7 | 3 | 147 |
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Read one row both ways: 149 twenty-foot #4 bars are a ton of steel, and so are 74 forty-foot bars — the same 2,000 lb, double the footage. When you compare two quotes, the ton is the same size but the truck is not: 40 ft stock covers twice the line length per bar, which matters more than the price per pound on jobs with long lines. The tonnage page carries the pounds-to-tons conversion and the short ton vs metric tonne trap.
Outside the US the standard stock bar is 12 m — 39 ft 4 in, close enough to the US 40 ft that the two interconvert cleanly — with 6 m (19 ft 8 in) common for residential grids, short lines and one-person handling:
| Metric size | kg/m | 12 m bar (kg) | 6 m bar (kg) |
|---|---|---|---|
| 10 mm | 0.617 | 7.4 | 3.7 |
| 12 mm | 0.888 | 10.7 | 5.3 |
| 16 mm | 1.578 | 18.9 | 9.5 |
| 20 mm | 2.466 | 29.6 | 14.8 |
| 25 mm | 3.853 | 46.2 | 23.1 |
| 28 mm | 4.834 | 58.0 | 29.0 |
| 32 mm | 6.313 | 75.8 | 37.9 |
| 40 mm | 9.865 | 118.4 | 59.2 |
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Working across the two systems: a 12 m bar covers a 39 ft line in one piece where the US needs a 40 ft stock bar plus a lap — and the metric ton (2,204.6 lb) is 10.2% heavier than the US short ton, so a “ton” quoted across the border is not the same number. The size chart has the full metric and imperial conversion tables for both diameters and weights.
In the US, rebar is stocked in 20 ft and 40 ft lengths, and 60 ft is available from some mills by special order. In metric countries the standard stock length is 12 m — about 39 ft 4 in — with 6 m (about 19 ft 8 in) common for shorter jobs and easier handling. Always confirm the stocked lengths with your yard before the takeoff.
A full 20 ft bar weighs its weight per foot times 20: #3 is 7.5 lb, #4 is 13.4 lb, #5 is 20.9 lb, #6 is 30.0 lb, #8 is 53.4 lb and #18 is 272.0 lb. A 40 ft bar is exactly double — #4 is 26.7 lb and #8 is 106.8 lb. These are nominal ASTM A615 / A706 weights; coated bars add weight on top.
Then it is two bars joined by a lap splice, and the lap length is steel you buy on top of the line itself. The field rule of thumb is 40 times the bar diameter, never less than 12 in: 20 in for #4, 25 in for #5, 30 in for #6, 40 in for #8. A 24 ft line on 20 ft stock is two bars and one lap; the same line on 40 ft stock is one bar with no lap at all. ACI 318 sets the required splice, and the drawings govern.
A 24 ft line needs two 20 ft bars with one 20 in lap (#4), or a single 40 ft bar with no lap. Which is cheaper is a whole-job question: 40 ft stock buys the line outright, but leaves a 16 ft offcut per bar if the rest of the job is short lines, so run the whole takeoff on both stock lengths before ordering.
You order a bar count and you are invoiced by the pound. Suppliers ship whole stock lengths, so the order is a number of 20 ft or 40 ft bars; the invoice is that count times the length times the weight per foot. Give the yard both numbers — 10 bars of 20 ft #4 is also 200 ft and 133.6 lb.
A short ton is 2,000 lb, so divide by the weight of a full stock bar and round down: on 20 ft stock that is 149 bars of #4, 95 of #5, 66 of #6, 37 of #8 and 7 of #18. On 40 ft stock every figure halves — #4 is 74 bars per ton — because each bar is double the weight.
No. Metric stock is 12 m in most of the world, but 6 m bars are common for residential work, and mills in some regions ship 10 m or other lengths. The 12 m bar is 39 ft 4 in — not exactly 40 ft — so treat cross-system estimates as close, not equal.
Transport and handling. 20 ft bars ship on a standard flatbed without permits, ride a forklift two at a time, and cut cleanly into the short lines most residential grids need. 40 ft length comes from mill rolling and rail limits and halves the number of laps on long lines. 60 ft exists, but needs a longer truck and is often a special order.