If you estimate in pounds and the drawings came from Europe, the UK, Australia, or anywhere else metric, every member weight has to be converted before it goes into your takeoff. The math is one multiplication. The mistakes come from which number you multiply.
The conversion factor
1 kg/m = 0.67197 lb/ft
It comes straight from the unit definitions: 1 kg = 2.20462 lb and 1 m = 3.28084 ft, so 2.20462 ÷ 3.28084 = 0.671969.
Going the other way:
1 lb/ft = 1.48816 kg/m
Examples:
- An IPE 300 at 42.2 kg/m is 42.2 × 0.67197 = 28.36 lb/ft
- A W12x26 at 26 lb/ft is 26 × 1.48816 = 38.7 kg/m
For a quick mental check, kg/m × 2/3 is close to lb/ft. It's about 0.8% low, fine for a sanity check and too loose for a bid.
UK universal beams (UB): kg/m to lb/ft
Masses and depths below are from the ArcelorMittal sections catalogue (V2024-1), as carried in our audited section data. The lb/ft column is mass × 0.67197.
| Section | Mass (kg/m) | Weight (lb/ft) | Depth (mm) |
|---|---|---|---|
| UB 203 x 133 x 25 | 25.1 | 16.87 | 203.2 |
| UB 254 x 146 x 31 | 31.1 | 20.90 | 251.4 |
| UB 305 x 165 x 40 | 40.3 | 27.08 | 303.4 |
| UB 356 x 171 x 45 | 45.0 | 30.24 | 351.4 |
| UB 406 x 178 x 54 | 54.1 | 36.35 | 402.6 |
| UB 457 x 191 x 67 | 67.1 | 45.09 | 453.4 |
| UB 533 x 210 x 82 | 82.2 | 55.24 | 528.3 |
| UB 610 x 229 x 101 | 101.0 | 67.87 | 602.6 |
Notice that the catalogue mass isn't always the number in the name. The UB 305 x 165 x 40 is 40.3 kg/m, and its actual depth is 303.4 mm, not 305. More on that below. The UK UB and UC sizes chart has the full range.
UK universal columns (UC)
| Section | Mass (kg/m) | Weight (lb/ft) | Depth (mm) |
|---|---|---|---|
| UC 152 x 152 x 23 | 23.0 | 15.46 | 152.4 |
| UC 152 x 152 x 30 | 30.0 | 20.16 | 157.6 |
| UC 203 x 203 x 46 | 46.1 | 30.98 | 203.2 |
| UC 203 x 203 x 60 | 60.0 | 40.32 | 209.6 |
| UC 254 x 254 x 73 | 73.1 | 49.12 | 254.1 |
| UC 254 x 254 x 89 | 88.9 | 59.74 | 260.3 |
| UC 305 x 305 x 97 | 96.9 | 65.11 | 307.9 |
| UC 305 x 305 x 118 | 118.0 | 79.29 | 314.5 |
IPE beams
| Section | Mass (kg/m) | Weight (lb/ft) | Depth (mm) |
|---|---|---|---|
| IPE 140 | 12.9 | 8.67 | 140.0 |
| IPE 160 | 15.8 | 10.62 | 160.0 |
| IPE 200 | 22.4 | 15.05 | 200.0 |
| IPE 240 | 30.7 | 20.63 | 240.0 |
| IPE 270 | 36.1 | 24.26 | 270.0 |
| IPE 300 | 42.2 | 28.36 | 300.0 |
| IPE 360 | 57.1 | 38.37 | 360.0 |
| IPE 400 | 66.3 | 44.55 | 400.0 |
| IPE 450 | 77.6 | 52.14 | 450.0 |
| IPE 500 | 90.7 | 60.95 | 500.0 |
HEA (HE A) sections
| Section | Mass (kg/m) | Weight (lb/ft) | Depth (mm) |
|---|---|---|---|
| HE 140 A | 24.7 | 16.60 | 133.0 |
| HE 160 A | 30.4 | 20.43 | 152.0 |
| HE 200 A | 42.3 | 28.42 | 190.0 |
| HE 240 A | 60.3 | 40.52 | 230.0 |
| HE 260 A | 68.2 | 45.83 | 250.0 |
| HE 300 A | 88.3 | 59.33 | 290.0 |
| HE 360 A | 112.0 | 75.26 | 350.0 |
| HE 400 A | 125.0 | 84.00 | 390.0 |
HE A is the lightest of the HE family. HE B and HE M sections of the same serial size are much heavier, so read the letter carefully. The HEA vs HEB vs HEM guide covers the differences, and the European steel sections guide covers the rest of the EN catalogue.
UK square hollow sections (SHS)
Masses from the SCI Blue Book tables as carried in our section data.
| Section | Mass (kg/m) | Weight (lb/ft) |
|---|---|---|
| SHS 50x50x5 | 6.8 | 4.57 |
| SHS 60x60x5 | 8.4 | 5.64 |
| SHS 80x80x5 | 11.6 | 7.79 |
| SHS 100x100x5 | 14.7 | 9.88 |
| SHS 100x100x6.3 | 18.2 | 12.23 |
| SHS 120x120x6.3 | 22.2 | 14.92 |
| SHS 150x150x8 | 35.1 | 23.59 |
| SHS 200x200x10 | 58.8 | 39.51 |
| SHS 250x250x10 | 74.5 | 50.06 |
Australian UB and UC (AS/NZS 3679.1)
Australian designations put the mass per metre right in the name, and it matches the catalogue mass.
| Section | Mass (kg/m) | Weight (lb/ft) |
|---|---|---|
| 200UB25.4 | 25.4 | 17.07 |
| 250UB31.4 | 31.4 | 21.10 |
| 310UB40.4 | 40.4 | 27.15 |
| 360UB50.7 | 50.7 | 34.07 |
| 410UB59.7 | 59.7 | 40.12 |
| 200UC46.2 | 46.2 | 31.05 |
| 250UC72.9 | 72.9 | 48.99 |
| 310UC96.8 | 96.8 | 65.05 |
See the AS/NZS steel sections guide for the full range and the naming rules.
Reverse: common W shapes in kg/m
For sending a US takeoff to a metric client, or checking a Canadian drawing. Weights and depths are from the AISC shape data we carry. The kg/m column is lb/ft × 1.48816. The metric designation column is the paired metric name from the Canadian Institute of Steel Construction (CISC) list of readily available W shapes.
| W shape | Weight (lb/ft) | Mass (kg/m) | Metric designation (CISC) | Depth (in / mm) |
|---|---|---|---|---|
| W8x18 | 18 | 26.8 | W200x27 | 8.14 / 207 |
| W8x31 | 31 | 46.1 | W200x46 | 8.00 / 203 |
| W10x22 | 22 | 32.7 | W250x33 | 10.17 / 258 |
| W10x33 | 33 | 49.1 | W250x49 | 9.73 / 247 |
| W12x26 | 26 | 38.7 | W310x39 | 12.22 / 310 |
| W12x40 | 40 | 59.5 | W310x60 | 11.94 / 303 |
| W12x65 | 65 | 96.7 | W310x97 | 12.12 / 308 |
| W14x22 | 22 | 32.7 | W360x33 | 13.74 / 349 |
| W14x30 | 30 | 44.6 | W360x45 | 13.84 / 352 |
| W14x48 | 48 | 71.4 | W360x72 | 13.79 / 350 |
| W14x90 | 90 | 133.9 | W360x134 | 14.02 / 356 |
| W16x26 | 26 | 38.7 | W410x39 | 15.69 / 399 |
| W16x40 | 40 | 59.5 | W410x60 | 16.01 / 407 |
| W18x35 | 35 | 52.1 | W460x52 | 17.70 / 450 |
| W18x50 | 50 | 74.4 | W460x74 | 17.99 / 457 |
| W21x44 | 44 | 65.5 | W530x66 | 20.66 / 525 |
| W21x62 | 62 | 92.3 | W530x92 | 21.00 / 533 |
| W24x55 | 55 | 81.8 | W610x82 | 23.57 / 599 |
| W24x76 | 76 | 113.1 | W610x113 | 23.92 / 608 |
| W27x94 | 94 | 139.9 | W690x140 | 26.92 / 684 |
| W30x108 | 108 | 160.7 | W760x161 | 29.83 / 758 |
Single-shape pages with dimensions are in the steel shapes reference, for example W12x26 and W8x18. For choosing the nearest European or UK section rather than just converting the weight, use the W-shape metric equivalents chart.
Pitfalls
1. Nominal vs actual mass
UK designations like UB 305 x 165 x 40 are serial sizes. The "305 x 165" is a nominal depth and width, and the "40" is a rounded mass. The catalogue mass is 40.3 kg/m. If you convert the designation instead of the catalogue value, you're about 0.7% light on that member. On one beam nobody cares. On 200 tonnes of UB it's a tonne and a half of steel you didn't price.
The US has the same issue in a smaller way. AISC's nominal weight (the 26 in W12x26) is very close to the weight calculated from the section's area, but not identical. For W12x26 the area is 7.65 in², which gives 7.65 × 3.4028 = 26.03 lb/ft. US practice is to use the nominal weight, and the difference is negligible, but don't mix the two methods in one takeoff. How to calculate steel beam weight goes through the area method.
Rule: convert the catalogue mass, not the number in the name, unless your client specifically wants nominal.
2. Metric designations are rounded too
The CISC table pairs W8x18 with W200x27. The straight conversion is 18 × 1.48816 = 26.8 kg/m, so the "27" in the metric name is a rounded label, not a precise mass. Don't back-calculate lb/ft from a metric W name and expect it to match the imperial nominal weight exactly.
3. Mass vs weight
Kilograms measure mass. Pounds are used for both mass and force in US practice, which is why this conversion works for estimating: we're converting how much steel you're buying, not a load.
Engineers working in SI will often give member self-weight as a load in kN/m, not kg/m. To go from kg/m to kN/m, multiply by 9.81 and divide by 1,000. A 42.2 kg/m IPE 300 is about 0.41 kN/m. If a metric schedule lists a number in kN/m and you convert it as if it were kg/m, your weight will be off by a factor of roughly 100.
4. Tonnes vs tons
A metric tonne is 1,000 kg, or 2,204.6 lb. A US short ton is 2,000 lb. One tonne is 1.1023 short tons. If a European supplier quotes per tonne and you bid per ton, convert the price as well as the weight. A 10% gap in the unit will look like a pricing error on the bid review.
5. Hot-finished vs cold-formed hollow sections
A hot-finished SHS and a cold-formed SHS with the same nominal dimensions don't have the same mass, because the corner radii are different. UK drawings don't always say which one they mean. Find out before you convert, or ask the engineer.
6. Rounding once
Convert from the catalogue value with the full factor, then round the total. Don't round the kg/m, convert, round the lb/ft, multiply by length, and round again. Each step is small; the stack adds up across a large job.
Converting a full takeoff
For a mixed-standard set, keep both columns in your takeoff: the metric mass from the catalogue and the lb/ft you're pricing with. That way the reviewer can check the conversion, and if the client asks for a metric summary you already have it. Steelflo reads sections from six standards off PDF drawings and keeps the weights in consistent units, so a set with UB, IPE and W shapes on the same sheets ends up in one takeoff. See how it works.
Frequently Asked Questions
How do I convert kg/m to lb/ft for steel?
Multiply the mass in kg/m by 0.67197. For example, an IPE 300 at 42.2 kg/m weighs about 28.36 lb/ft. The factor comes from 2.20462 lb per kg divided by 3.28084 ft per metre.
How do I convert lb/ft to kg/m?
Multiply lb/ft by 1.48816. A W12x26 at 26 lb/ft is about 38.7 kg/m.
Should I convert the mass in the section name or the catalogue mass?
Use the catalogue mass. UK designations such as UB 305 x 165 x 40 use a rounded mass in the name, while the catalogue value is 40.3 kg/m. The difference is small per member but adds up on large jobs.
What is the difference between kg/m and kN/m?
kg/m is mass per metre and kN/m is load per metre. Multiply kg/m by 9.81 and divide by 1,000 to get kN/m. Don't convert a kN/m value as if it were kg/m, or the result will be off by about 100 times.
Is a metric tonne the same as a ton?
No. A metric tonne is 1,000 kg, or about 2,204.6 lb, while a US short ton is 2,000 lb. One tonne equals about 1.1023 short tons, so convert prices as well as weights.