Every bar size in lb/ft, where the number comes from, and what a scale says instead
← Back to the calculatorThe per-foot figure is fixed by the bar designation, not by the bar in front of you: 0.668 for #4, 1.502 for #6, 2.670 for #8, straight out of the A615 column. The formulas further down reproduce that column — area × 12 × 0.2836 lb/in³ for steel, d² ÷ 162.2 in metric — but they are arithmetic, and this page labels them as arithmetic. Where a formula and the A615 table disagree, the A615 table is the number to use. How to check a stick on a scale is on the rebar measurement page.
But the weight that pays the invoice is not the steel in the slab — it is the steel you order, which also carries the laps and the offcut. Both are split out below.
These are nominal values from ASTM A615, not a scale reading — for settlement and for ordering, use the measured weight on the mill certificate.
Everything on this page comes out of these. The first two are exact; the third is the one you can do in your head.
The third line is the useful one: 4² ÷ 24 = 0.67 lb/ft. It works for any bar number up to about #8, and it is why doubling the bar number roughly quadruples the weight.
Not the number in the table. ASTM A615 fixes pounds per foot by bar designation, and footnote A to that table defines the nominal dimensions of a deformed bar as those of a plain round bar having the same weight per foot — so the figure is a definition attached to the designation, not a measurement of the bar you are holding. A #4 is 0.668 lb/ft in the table whether it is black, epoxy-coated or galvanised.
What the film does change is the outside diameter, because it sits on both sides of the bar:
| Bar | Nominal OD (in) | Coated OD at 7 mil | Coated OD at 12 mil | Film area at 7 mil (in²) | Film area at 12 mil (in²) | Film area vs steel area |
|---|---|---|---|---|---|---|
| #3 | 0.375 | 0.389 | 0.399 | 0.0084 | 0.0146 | 7.6% / 13.2% |
| #4 | 0.500 | 0.514 | 0.524 | 0.0111 | 0.0193 | 5.7% / 9.8% |
| #5 | 0.625 | 0.639 | 0.649 | 0.0139 | 0.0240 | 4.5% / 7.8% |
| #6 | 0.750 | 0.764 | 0.774 | 0.0166 | 0.0287 | 3.8% / 6.5% |
| #7 | 0.875 | 0.889 | 0.899 | 0.0194 | 0.0334 | 3.2% / 5.6% |
| #8 | 1.000 | 1.014 | 1.024 | 0.0221 | 0.0382 | 2.8% / 4.9% |
Swipe the table sideways on a phone.
The last column is area, not weight, and the difference matters. Turning an area into a mass needs the density of the cured film, and cured epoxy is a good deal lighter than steel, so the mass share is smaller than the area share — not equal to it. This page does not have a sourced density for cured fusion-bonded epoxy, so the arithmetic stops at area and no weight percentage is quoted here. A percentage published without the density behind it is a guess wearing a number.
The 0.014 to 0.024 in is computed from the film, not measured on every bar. ASTM A775 accepts a coating when at least 90% of all recorded thickness measurements after curing are 7 to 12 mil, which means a bar can sit at the thin end of that band at one point and the thick end at another: one bar gains 0.014 in here and 0.024 in there. Read the coated-OD columns as the band a bar can fall in, not as a fixed size.
The film is also not the largest gap between the table and the scale. A615 evaluates bars on nominal weight and accepts a measured weight at 94% of the nominal value — 0.628 lb/ft on a #4 — and adds that overweight shall in no case be a cause for rejection. A 6% band on the scale is wider than anything a 12 mil film does to a 0.500 in diameter.
The five sizes that cover most residential and light commercial work. The complete chart — every imperial size from #3 to #18 and metric 10 mm to 40 mm, with areas and bars per ton — is in the rebar weight chart below; the rebar size and weight chart adds diameters and areas.
| Bar | lb / ft | 20 ft bar (lb) | 40 ft bar (lb) | lb per 100 ft |
|---|---|---|---|---|
| #3 | 0.376 | 7.5 | 15.0 | 37.6 |
| #4 | 0.668 | 13.4 | 26.7 | 66.8 |
| #5 | 1.043 | 20.9 | 41.7 | 104.3 |
| #6 | 1.502 | 30.0 | 60.1 | 150.2 |
| #8 | 2.670 | 53.4 | 106.8 | 267.0 |
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| Size | kg / m | 12 m bar (kg) | kg per 100 m |
|---|---|---|---|
| 10 mm | 0.617 | 7.4 | 61.7 |
| 12 mm | 0.888 | 10.7 | 88.8 |
| 16 mm | 1.578 | 18.9 | 157.8 |
| 20 mm | 2.466 | 29.6 | 246.6 |
| 25 mm | 3.853 | 46.2 | 385.3 |
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For a square grid, a one-foot square of slab holds one foot of bar in each direction — two feet of bar in total. So the weight per square foot is just 2 ÷ spacing × weight per foot, and at 24 in spacing it is the weight per foot itself.
| Bar | lb / ft | 12 in | 16 in | 18 in | 24 in |
|---|---|---|---|---|---|
| #3 | 0.376 | 0.752 | 0.564 | 0.501 | 0.376 |
| #4 | 0.668 | 1.336 | 1.002 | 0.891 | 0.668 |
| #5 | 1.043 | 2.086 | 1.564 | 1.391 | 1.043 |
| #6 | 1.502 | 3.004 | 2.253 | 2.003 | 1.502 |
| #8 | 2.670 | 5.340 | 4.005 | 3.560 | 2.670 |
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Read it as pounds of rebar per square foot of slab. A #4 grid at 12 in on centre is 1.336 lb/sq ft; the same #4 at 18 in drops to 0.891 lb/sq ft.
For a whole pour rather than a square foot — bars, feet and pounds for a patio, shed, garage, driveway or walkway slab — the how much rebar do I need page runs the same arithmetic row by row.
A 24 ft × 20 ft slab, #4 bar at 12 in on centre, 3 in edge clearance, 20 ft stock bars. The takeoff gives 938 ft of steel in the slab and 49 bars to order. Here is what each part weighs.
| Part | Length | Working | Weight |
|---|---|---|---|
| Steel in the slab | 938 ft | 938 × 0.668 | 626.6 lb |
| Laps (20 laps × 25 in) | 41.7 ft | 41.67 × 0.668 | 27.8 lb |
| Offcut (49 bars = 980 ft) | 0.3 ft | 0.33 × 0.668 | 0.2 lb |
| Order weight | 980 ft | 980 × 0.668 | 654.6 lb |
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The three parts add to 654.6 lb exactly. You pay for 654.6 lb and you install 626.6 lb. The 28 lb difference is laps and offcut — 4.3% of the order, and it is real money at any price per pound.
All the figures on this site are nominal: they come from the bar designation through ASTM A615, not from a bar on a scale. A coating does not change the nominal figure — the film sits outside the nominal diameter, and what it adds to the measured diameter is worked out above. What moves the scale is the rolling tolerance, and clause 11.1 puts its floor at 94% of nominal.
Yards quote either per bar or per pound, and the two are not interchangeable — a per-bar price already carries the offcut, a per-pound price does not. Convert with one multiplication:
Take the 654.6 lb order above. At a quoted $0.85 per pound it is $556; at $1.10 per pound it is $720. Substitute your own quote — the point is that a 4.3% weight difference between two takeoffs is a 4.3% difference in the bill, so it is worth getting the laps right before you order rather than after.
A per-bar and a per-pound quote are only comparable once both are in the same unit, and the same is true of the per-foot, per-hundredweight and per-ton quotes a yard may hand you. The rebar price per foot page converts all five units to one dollars-per-pound figure, and shows why a price per foot cannot be compared across bar sizes at all.
The metric rule is shorter than the imperial one and just as easy to do in your head: kg/m = d² ÷ 162.2, with d in millimetres.
A standard 12 m bar is the length that matters in metric markets, so 16 mm bar is 18.9 kg per stick and about 52 sticks to the tonne. The full metric table, including areas and bars per tonne, is on the size and weight chart.
#4 is the size most people search for by name, so here it is on its own:
| Measure | #4 (0.500 in / 12.7 mm) |
|---|---|
| Per foot | 0.668 lb |
| Per 20 ft stick | 13.4 lb |
| Per 40 ft stick | 26.7 lb |
| Per 100 ft | 66.8 lb |
| Per metre | 0.994 kg |
| 40 ft bars per ton | about 74 |
| Feet per ton | about 2,994 ft |
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Two independent routes agree here, which is a good way to check any rebar weight: 0.668 lb/ft × 1.4882 = 0.994 kg/m, and 12.7² ÷ 162.2 = 0.994 kg/m. Same bar, two formulas, 0.03% apart.
A rebar weight chart is the lookup table behind every weight number on this page: every imperial size from #3 to #18 and every metric size from 10 mm to 40 mm, in the four numbers a yard actually quotes — pounds per foot (mill certificates and per-pound pricing), pounds per full bar (what you lift, load and strap down), bars per ton (what you order), and kilograms per metre (metric drawings). The nominal weights are the ASTM A615 values, calculated from the bar designation and the density of steel, not measured off a bar.
Three numbers to read first: #4 is 0.668 lb/ft, a 20 ft #4 bar is 13.4 lb, and a short ton holds 149 of them on 20 ft stock. Everything below is the same three numbers for every size.
| Bar | lb / ft | kg / m | 20 ft bar (lb) | 40 ft bar (lb) | Bars / short ton (20 ft) | Bars / short ton (40 ft) |
|---|---|---|---|---|---|---|
| #3 | 0.376 | 0.560 | 7.5 | 15.0 | 265 | 132 |
| #4 | 0.668 | 0.994 | 13.4 | 26.7 | 149 | 74 |
| #5 | 1.043 | 1.552 | 20.9 | 41.7 | 95 | 47 |
| #6 | 1.502 | 2.235 | 30.0 | 60.1 | 66 | 33 |
| #7 | 2.044 | 3.042 | 40.9 | 81.8 | 48 | 24 |
| #8 | 2.670 | 3.973 | 53.4 | 106.8 | 37 | 18 |
| #9 | 3.400 | 5.060 | 68.0 | 136.0 | 29 | 14 |
| #10 | 4.303 | 6.404 | 86.1 | 172.1 | 23 | 11 |
| #11 | 5.313 | 7.907 | 106.3 | 212.5 | 18 | 9 |
| #14 | 7.650 | 11.384 | 153.0 | 306.0 | 13 | 6 |
| #18 | 13.600 | 20.239 | 272.0 | 544.0 | 7 | 3 |
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The bars-per-ton column is rounded down, not to the nearest whole bar: 96 twenty-foot #5 bars weigh 2,002.6 lb, which is over a short ton, so a ton buys 95. That is the same floor rule the tonnage page uses when it turns a tonnage target into a purchase order.
| Metric | kg / m | lb / ft | 12 m bar (kg) | 6 m bar (kg) | Bars / tonne (12 m) |
|---|---|---|---|---|---|
| 10 mm | 0.617 | 0.415 | 7.4 | 3.7 | 135 |
| 12 mm | 0.888 | 0.597 | 10.7 | 5.3 | 93 |
| 16 mm | 1.578 | 1.060 | 18.9 | 9.5 | 52 |
| 20 mm | 2.466 | 1.657 | 29.6 | 14.8 | 33 |
| 25 mm | 3.853 | 2.589 | 46.2 | 23.1 | 21 |
| 28 mm | 4.834 | 3.249 | 58.0 | 29.0 | 17 |
| 32 mm | 6.313 | 4.242 | 75.8 | 37.9 | 13 |
| 40 mm | 9.864 | 6.629 | 118.4 | 59.2 | 8 |
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Each column answers a different question. Pounds per foot is what mill certificates and per-pound pricing run on — 1,000 ft of #5 is 1,043 lb of steel whatever length you buy it in. Pounds per full bar is what you lift, load and strap down — a 20 ft #4 is a one-hand lift at 13.4 lb, while a single 40 ft #18 bar is 544.0 lb and needs equipment. Bars per ton is what the yard invoices on when the order is placed by weight. And kg/m is what a metric drawing hands you.
Work the chart in the direction the quote goes. Two short tons of #5 on 20 ft stock: the chart says #5 is 1.043 lb/ft, so a 20 ft bar is 20.9 lb, and 2,000 ÷ 20.9 = 95.8 — rounded down to 95 whole bars. Those 95 bars are 1,900 ft = 1,981.7 lb = 0.99 short tons. Order the 96th bar and you have bought 2,002.6 lb, two and a half pounds over the ton you were quoted.
Two things the chart will not do. It is nominal weight — the mill certificate settles a payment, because rolling tolerance moves a real bar by a fraction of a percent. And the mental shortcut bar number² ÷ 24 only matches the chart up to #8 (within 0.3%); by #11 it reads 5.1% light, which is exactly the drift the measurement page traces to the same root cause. For anything above #8, read the table.
#4 weighs 0.668 lb per foot, #5 is 1.043, #6 is 1.502 and #8 is 2.670. For any imperial size #3 to #8 the quick estimate is the bar number squared divided by 24, so 4² = 16, divided by 24 gives 0.67 lb per foot. In metric, kilograms per metre = diameter² ÷ 162.2, so a 16 mm bar is 1.578 kg/m.
A #4 bar weighs 0.668 lb per foot. That is 13.4 lb for a 20 ft stick and 26.7 lb for a 40 ft stick, and roughly 74 forty-foot bars to a ton. The metric equivalent, 12.7 mm, comes out at 0.994 kg/m, so the two systems agree to within 0.05%.
Because you buy whole bars. The steel in the slab is the net length, and on top of that you carry the laps where bars join and the offcut left at the end of each line. On a 24 ft × 20 ft slab with 20 ft bars, 626.6 lb of steel in the slab becomes a 654.6 lb order: 27.8 lb of laps and 0.2 lb of offcut.
One pound per foot is 1.4882 kilograms per metre, so 0.668 lb/ft is 0.994 kg/m. Going the other way, one kilogram per metre is 0.6720 pounds per foot. For the same nominal bar the two systems agree to within 0.05%.
Every rebar size in one table — imperial #3 through #18 and metric 10 mm through 40 mm — with the four numbers a yard quotes: pounds per foot, kilograms per metre, the weight of a full stock bar (20 ft and 40 ft, or 12 m and 6 m), and how many whole bars fit in a ton. The anchor row is #4: 0.668 lb/ft, 13.4 lb per 20 ft stick, 149 bars per short ton on 20 ft stock. Read the per-foot column for pricing, the per-bar column for handling, and the per-ton column when the order is placed by weight. The full chart is in the rebar weight chart section above.
Not the nominal weight. ASTM A615 fixes pounds per foot by bar designation, so a #4 is 0.668 lb/ft coated or black. What the film changes is the outside diameter: 7 to 12 mil on both sides adds 0.014 to 0.024 in, taking a #4 from 0.500 to 0.514–0.524 in. The film cross-section on a #4 is 0.0111 to 0.0193 in², which is 5.7% to 9.8% of the bar's 0.1963 in² steel area — area, not mass. Converting that to a weight percentage needs the density of the cured film, which this page does not carry, so no percentage is quoted.
To 94% of the ASTM A615 value. ASTM A615 evaluates bars on nominal weight and requires the measured weight of the test specimen to be at least 94% of the tabulated weight per unit length, which on a #4 is 0.628 lb/ft. The same clause says overweight shall in no case be a cause for rejection. A 6% band on the scale is wider than anything a 12 mil coating does to a 0.500 in diameter.