Steel weight calculator
This weighs the metal in the section you describe, at the density you enter. Mill tolerances, coatings and the exact alloy nudge the real figure, so lean on the supplier's certificate for anything that has to be exact, and add a margin for rigging.
Choose the section, enter its size and length and how many you have, and the tool returns the weight in pounds and kilograms. The density field is what makes it work for any metal — the default is plain steel, but stainless or aluminium is one edit away.
Exemple détaillé
A 1-inch square steel bar, 10 feet long: the cross-section is 1 in², so the volume is 1 × 120 = 120 cubic inches. At 0.2836 lb/in³ that is 120 × 0.2836 ≈ 34 lb, or about 15.4 kg — near enough the 3.4 lb-per-foot a handbook lists. In metric: a 25 mm square bar 3 m long is 0.025 × 0.025 × 3 = 0.001875 m³, × 7,850 kg/m³ ≈ 14.7 kg.
Sur le chantier
Plate, before you send two people for it. A ¼ in × 4 × 8 ft plate is 0.25 × 48 × 96 = 1,152 in³ × 0.2836 = 327 lb. Half-inch is 653. Per square foot the rule is 40.8 lb × the thickness in inches — 10.2 lb/ft² for ¼, 20.4 for ½ — so a 2 ft × 3 ft piece of ⅜ is 6 × 15.3 = 92 lb, a one-person carry with gloves and a bad idea without. Metric plate runs 7.85 kg/m² per millimetre of thickness: a 6 mm × 1.2 × 2.4 m sheet is 2.88 m² × 47.1 = 136 kg.
Pipe from the OD and wall. The tool's round tube takes the outside diameter and the wall. A 2 in pipe with a 2.375 in OD and 0.154 in wall has a metal area of π ÷ 4 × (2.375² − 2.067²) = 1.07 in²; × 12 in × 0.2836 = 3.65 lb/ft, which is what the mill tag says. Type the OD and the wall off the tag, not the nominal size — a "2 inch" pipe is not 2 in anywhere. In millimetres the same pipe is 60.3 OD × 3.91 wall: π ÷ 4 × (60.3² − 52.48²) = 693 mm², × 7,850 kg/m³ = 5.44 kg/m.
A rack of flat bar. Twenty pieces of 3 × ⅜ × 20 ft: each is 1.125 in² × 240 in × 0.2836 = 76.6 lb, so the bundle is 1,530 lb. Change the density to 0.098 and the same bundle in aluminium is 530 — a third. Stainless at 0.29 is a touch heavier than mild steel. The metric version: twenty 75 × 10 mm flats, 6 m long, are 0.075 × 0.01 × 6 × 7,850 = 35.3 kg each, 707 kg the bundle — or 243 kg in aluminium at 2,700 kg/m³.
What went wrong?
Quick referencefor steel
- Mild steel
- 0,2836 lb/in³ · 490 lb/ft³ · 7 850 kg/m³
- Plate, lb per ft²
- 40.8 × thickness (in) — ⅛ 5.1 · ¼ 10.2 · ⅜ 15.3 · ½ 20.4 · 1 in 40.8
- Round bar, lb per ft
- 2.67 × d² — ½ in 0.67 · 1 in 2.67 · 2 in 10.7
- Square bar, lb per ft
- 3.40 × s² · flat bar: 3.40 × width × thickness
- Plate, kg per m²
- 7.85 × thickness (mm) — 3 mm 23.6 · 6 mm 47.1 · 10 mm 78.5 · 12 mm 94.2
- Round bar, kg per m
- 0.00617 × d² (mm) — 10 mm 0.62 · 20 mm 2.47 · 25 mm 3.85
- Other metals
- aluminium 0.098 lb/in³ (about ⅓) · stainless 0.29 · brass 0.31 · copper 0.32 — in kg/m³ about 2,700 · 8,000 · 8,500 · 8,900
- Unités
- lb × 0,4536 = kg · lb/in³ × 27,68 = g/cm³
Mistakes to catchbefore you trust the number
- Weighing tube as solid bar: the tube shapes subtract the hollow, so pick the tube shape and type the wall thickness.
- Using the steel density for aluminium — aluminium is about a third of the weight, and stainless is a touch heavier than mild steel.
- Typing the plate's length in feet and thickness in inches into fields set to one unit; check the suffixes.
La formule
weight = cross-section area × length × density · tube area = outer − hollow
Every shape comes down to an area times a length for the volume, then volume times density for the weight. A hollow section subtracts the inside area from the outside, so only the wall metal is counted. Plate is just length × width × thickness.
Questions
- How do I calculate the weight of steel?
- Work out the volume of the piece — cross-sectional area times length — and multiply by the density of the metal. Steel is about 7,850 kg per cubic metre, or 0.2836 pounds per cubic inch. A 1-inch square bar 10 feet long is 10 lb per foot, near enough 34 lb in total.
- Does this work for stainless or aluminium?
- Yes — change the density field. Mild and stainless steel are close, around 7,850 to 8,000 kg/m³, but aluminium is roughly a third the weight at about 2,700 kg/m³. The density is a field precisely so you can enter the metal you actually have rather than assume plain steel.
- How do I weigh tube or pipe?
- Pick the round or square tube shape and enter the outside size and the wall thickness. The tool takes the area of the outer shape and subtracts the hollow inside, so you are only weighing the metal in the wall — which is why a tube is so much lighter than a solid bar the same size.
- Why does my supplier quote a different weight?
- Rolling tolerances, coatings and the exact alloy all shift the number a little, and a mill quotes to a published unit weight that may round differently. Treat this as a close estimate for handling, freight and load planning, and take the mill certificate as the figure of record.
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