How to use this calculator
- Pick the shape. Choose round bar, square or hex bar, flat bar/plate, round/square/rectangular tube, or angle. Only the relevant dimensions are shown.
- Pick the material. Select the metal (or plastic); its density is filled in from our cited table.
- Enter the size and length. Enter the cross-section dimensions, the length of one piece, and how many pieces.
- Add ordering allowance. Optionally add waste / overage for saw drops, trim, defects or mill minimums, and enter a price per kg if you want a rough material cost.
- Read the weight. Read the net total weight, order weight, estimated material cost, weight each, weight per length, volume, density used and cross-section area. Toggle metric/imperial in the header.
How it works
Every weight is the same calculation — weight = density × volume — where the
volume is the cross-section area times the length:
W = ρ · A · L
The only thing that changes between shapes is how the cross-section area A is found.
Working in g/cm³, mm² and mm, the weight in kilograms is
W = ρ · A · L / 1 000 000. The metal
weight formula guide walks through the unit conversion, and the
material density chart lists the density values used here.
The cross-section area for each shape:
- Round bar:
A = π/4 · d² - Square bar:
A = a² - Hex bar (across flats AF):
A = (√3/2) · AF² - Flat bar / plate:
A = w · t - Round tube / pipe:
A = π/4 · (OD² − ID²), ID = OD − 2t - Square tube:
A = a² − (a − 2t)² - Rectangular tube:
A = w·h − (w − 2t)(h − 2t) - Angle (L):
A = t · (a + b − t)
The weight per length (kg/m or lb/ft) is just ρ · A and is independent
of the length — it is the figure steel stockists quote. For nominal pipe sizes, the
pipe weight formula and
steel pipe schedule chart are usually faster
than entering OD and wall by hand.
For ordering, the calculator keeps the net calculated weight separate from order weight. Net weight is just the exact shape, length and quantity you entered. Order weight adds the waste / overage percentage for saw drops, trim, defects, remnant constraints or mill minimums. If you enter a price per kg, the estimated material cost is based on that order weight.
| Planning question | Use this result | What it answers |
|---|---|---|
| How heavy is the finished cut list? | Total weight | Net weight before ordering allowance. |
| How much metal should I plan to buy? | Order weight incl. overage | Net weight plus the entered waste / ordering allowance. |
| What supplier number should I sanity-check? | Weight per length | Stockist-style kg/m or lb/ft for the selected shape and material. |
| What is the rough material cost? | Estimated material cost | Order weight multiplied by your entered price per kg. |
Material, steel, stainless and bar weight searches
This same tool is also a material weight calculator, a steel weight calculator, a stainless steel weight calculator and a bar weight calculator. Choose the stock shape first, then choose the material density. For bar stock, select round, square, hex or flat bar; for stainless, pick the stainless grade from the material list so the weight follows the grade instead of a generic steel value.
For focused formula pages, see material weight calculator, steel weight calculator, stainless steel weight calculator, bar weight calculator, aluminum weight calculator, round bar weight calculator, steel plate weight calculator, steel tube weight calculator, square tube weight calculator, 304 stainless weight calculator, 316 stainless weight calculator, steel weight, stainless steel weight, round bar weight, plate weight and square tube weight.
Worked example
Verified against the live calculator
A Ø25 mm mild-steel round bar, 1 m long. The cross-section is
A = π/4 × 25² = 490.9 mm². Mild steel is 7.85 g/cm³, so the weight per
metre is 7.85 × 490.9 / 1000 = 3.85 kg/m, and a 1 m length weighs
≈ 3.85 kg. With a 5% ordering allowance the order
weight is about 4.05 kg; at $2.50/kg that is about
$10.12 before tax, cutting, freight or supplier minimums.
Frequently asked questions
How do you calculate the weight of metal?
Weight is density × volume. Find the cross-section area for the shape (for a round bar, A = π/4 · d²), multiply by the length to get the volume, then multiply by the material density. In consistent units: weight (kg) = density (g/cm³) × area (mm²) × length (mm) ÷ 1,000,000. A Ø25 mm mild-steel round bar 1 m long is about 3.85 kg.
How much does steel weigh?
Mild and most low-alloy steels have a density of about 7.85 g/cm³ (0.284 lb/in³, 7,850 kg/m³). Stainless steel is a little heavier at about 8.0 g/cm³, and cast iron is lighter at roughly 7.2 g/cm³. Aluminum is about a third of steel at 2.70 g/cm³. This calculator uses cited densities from our material-density table.
How do I work out the weight of a steel tube or pipe?
For a round tube the cross-section is the outside area minus the bore: A = π/4 · (OD² − ID²), where ID = OD − 2 × wall thickness. Then weight = density × area × length. Select "Round tube / pipe", enter the outside diameter and wall thickness, and the calculator does the subtraction for you.
What is weight per metre (or per foot)?
It is the weight of one metre (or one foot) of the stock — density × cross-section area — and it does not depend on the length you enter. Steel stockists quote bar and tube in kg/m or lb/ft, so it is handy for ordering and for checking a supplier’s figure.
How do I estimate metal order weight and cost?
Use the waste / overage input for saw drops, trim, defects, mill minimums or ordering allowance. The order weight is the net calculated weight times that allowance. If you enter a material price per kg, the calculator multiplies order weight by that user-entered price. It is not a live commodity or supplier quote.
Does this handle aluminum, stainless, brass and plastics?
Yes. Pick the material from the list and the matching density is used automatically — carbon and alloy steels, stainless, cast iron, aluminum alloys, copper, brass and bronze, titanium, and common engineering plastics. The densities come from our cited material-density chart.
Why is the real weight slightly different from the calculator?
Densities are nominal handbook values; real alloy density varies a little with composition and temper, and mill stock has size tolerances, mill scale and (for tube) weld bead. Treat the result as an accurate estimate and verify against the mill certificate for critical or large orders.
Method & assumptions
- Densities are nominal room-temperature handbook values (ASM/MatWeb/manufacturer); real alloy density varies slightly with composition and temper.
- Sections are treated as ideal prisms — sharp corners, no corner radii, weld bead, mill scale or coating. Tube uses a constant wall thickness.
- Standard structural shapes (I-beam, channel, hot-rolled angle with root/toe radii) are a little lighter than the sharp-corner idealisation; use the published section weight for those.
- Material price is a user-entered estimate per kilogram, not a live steel, stainless, aluminum or supplier quote.
- For critical or large orders, verify against the mill certificate and stock tolerances.