Introduction
Beam weight questions come in two flavors: the ones everyone asks once (“what does W10×30 mean?”) and the ones that surface at the worst moment (“is that short tons or metric tons?”). This page answers both — the quick reference for designations, formulas, conversions, tolerances, and ordering, built around the canonical W10×30 at 20 ft (600 lb = 272.2 kg) so every answer uses numbers you can verify. Skim the headings for the answer you need, or read straight through for the complete picture.
For the interactive version of every calculation here, use the Steel Beam Weight Calculator — enter a designation and length, and it returns weight per foot, total weight, and metric equivalents instantly. The complete guide covers the same ground in tutorial form if you prefer to read start to finish.
Frequently Asked Questions
What does W10×30 mean?
W = wide-flange section, 10 = nominal depth in inches, 30 = weight in pounds per foot. So a W10×30 weighs 30 lb for every foot of length. The metric name for the same section is W250×44.6 (250 mm deep, 44.6 kg/m).
What is the formula for steel beam weight?
Total weight = weight per foot × length. For a W10×30 (30 lb/ft) at 20 ft: 30 × 20 = 600 lb, which is 600 × 0.453592 = 272.2 kg. The full derivation is in the formula-explained guide.
How do I convert lb/ft to kg/m?
Multiply by 1.48816. So 30 lb/ft = 44.65 kg/m, 50 lb/ft (W12×50) = 74.4 kg/m, and 104 lb/ft (W24×104) = 154.8 kg/m. The factor comes from the definitions: 0.45359237 kg per lb divided by 0.3048 m per ft.
How much does a 20-foot W10×30 weigh in kilograms?
272.2 kg. The fastest route: 30 lb/ft × 20 ft = 600 lb, then 600 × 0.453592 = 272.2 kg. Or entirely in metric: 44.65 kg/m × 6.096 m = 272.2 kg. Both routes must agree — if they don’t, check your units.
How much does a W10×30 beam weigh per foot?
30 lb per foot (44.65 kg/m) — it’s in the name. A 20-ft piece weighs 600 lb (272.2 kg); a 10-ft piece weighs 300 lb (136.1 kg). Length is the only other variable.
Does the steel grade change the beam’s weight?
No. A36, A572 Grade 50, and A992 all have the same density (490 lb/ft³), so a W10×30 weighs 30 lb/ft in every grade. Grade affects strength, weldability, and price — never the weight. Details in the material guide.
How accurate are published beam weights?
Published weights are nominal values from the AISC Steel Manual. Actual mill weights vary slightly within manufacturing tolerances — a small percentage either way, far smaller than the 2–5% connection allowance estimators carry. For ordering and freight, nominal weights are the industry standard basis; for crane picks near capacity limits, confirm actual piece weights with the supplier and keep margin.
What’s the difference between a short ton and a metric ton?
A US short ton is 2,000 lb; a metric ton (tonne) is 1,000 kg (2,204.6 lb) — about 10% heavier. The canonical 600-lb beam is 0.30 short tons or 0.272 metric tons. Always label which ton a quote uses; mixing them up is a classic pricing error.
Should I calculate on the span or the cut length?
The cut length — the actual piece you order and lift. Drawings usually dimension the clear span between supports, which is shorter than the beam. For the canonical example, the 20 ft is the ordered cut length, giving 600 lb.
Do I need to add anything for connections?
Yes, for budgeting. Plates, bolts, and stiffeners aren’t in the bare-beam weight; a planning allowance of 2–5% of the bare steel weight is standard practice until shop drawings give exact figures. The estimating guide shows how to include it.
How do I weigh a beam that’s already on site?
Read the designation stamped or stenciled on the beam (often on the web near one end), measure its length, and multiply — same formula, no scale needed. If the stamp is unreadable, measure the flange width, flange thickness, web thickness, and depth, and look up the closest matching section in a steel table before calculating.
Can I use the calculator for metric projects?
Yes. Enter the length in meters and work from the kg/m figure — 44.65 kg/m × 6.096 m = 272.2 kg for the canonical beam, identical to the imperial result. Use whichever system matches your drawings and supplier.
Does beam weight tell me if the beam is strong enough?
No — and this is the most important answer on this page. Weight tells you what you’re lifting, shipping, and paying for. Whether a beam can safely carry a given load is a structural design question for a licensed structural engineer, involving span, loading, deflection, and lateral bracing. See the code-compliance guide for the boundary.
Related Guides
- Complete Guide — the full tutorial: terms, worked example, and variations.
- Formula Explained — the derivation, conversions, and verified reference table.
- Material Guide — grades, metric designations, and finishes.
- Cost Guide — turning weight into a project budget.
- Estimating Guide — taking off a full beam schedule.
Get Your Number
If your question wasn’t answered above, the fastest path is to run the numbers yourself: the Steel Beam Weight Calculator takes a designation and a length and returns the weight per foot, total weight, and metric equivalents in one pass. Verify the designation against a published table, use the cut length, cross-check in the other unit system — and remember the one thing weight can’t tell you: whether the beam is structurally adequate, which is always an engineer’s call.
Disclaimer: Calculator results are planning estimates based on the beam designation and length you enter, using published nominal weights. Actual mill weights can vary slightly within manufacturing tolerances, and connection material adds weight on top of the bare beam. Verify final weights with your supplier, and consult a licensed structural engineer for all structural design and code-related decisions.
