Material Weight & Cost Calculator

What this tool does

CM8-01 is a raw material calculator for a whole cut list or bill of material. Each row is one part: its profile, material, dimensions, quantity, scrap allowance and supplier price. For every line it works out the theoretical weight per piece, the net weight, the weight you actually have to buy and the line cost. Across the list it totals the steel, metal and plastic you need, shows which material and which line drive the cost, and prices the allowance you are paying to cut away.

It covers twelve profiles — round, square, hex and flat bar, sheet and plate, round, square and rectangular tube, angle, channel, I-beam and tee — and 41 library materials, plus any material you can give a density for. Use it as a steel cost calculator for a fabrication quote, a metal cost calculator for machining blanks, or a quick weight check before a lift or a shipment. Everything runs inside this file: no account, no network request, and your dimensions and prices never leave this computer.

Weight comes from density

Every result reduces to one relationship:

Density is mass per unit volume, held here in kg/m³ (or lb/in³ in imperial). Mild steel is about 7,850 kg/m³, so a solid one-metre cube weighs 7.85 tonnes; aluminium at about 2,700 kg/m³ is roughly a third of that. Bars, tubes and sections have a constant cross-section, so their volume is the section area times the length, and the weight per metre is a property of the profile alone:

Internally the tool works in millimetres and kilograms: weight per piece in kg = volume in mm³ × ρ in kg/m³ × 10⁻⁹. Imperial entries are converted at the boundary and every result converted back.

Which dimensions each profile uses

The form has one set of dimension columns shared by every profile. Each profile reads only the columns named in its label; leave the others blank.

• Round bar — D diameter, L length. Square bar — D side, L. Hex bar — D across flats, L.
• Flat bar — W width, T thickness, L. Sheet / plate — L length, W width, T thickness.
• Round tube / pipe — D outside diameter, T wall, L. Square tube — D outside size, T wall, L. Rectangular tube — W and H outside, T wall, L.
• Angle — W leg a, H leg b, T thickness, L.
• Channel and I-beam — H depth, W flange width, Tw web thickness, T flange thickness, L. Tee — W flange width, H overall height, Tw stem, T flange, L.

A line is checked as you add it: a tube wall must be less than half the outside size, angle thickness less than both legs, flanges thinner than half the depth (thinner than the height on a tee), and a web or stem thinner than the flange width.

Shape formulas

Section areas used for each profile. Structural sections use the standard sharp-corner approximation.

Worked example. A 25 mm round bar of 304 stainless, 1 m long: A = π × 25² / 4 = 490.9 mm²; V = 490.9 × 1,000 = 490,874 mm³; W = 490,874 × 8,000 × 10⁻⁹ = 3.93 kg, which is also its weight per metre.

Cost, allowance and totals

Totals add only lines that can be calculated. A line without a price is weighed but not costed — it is shown as not priced and counted separately, never as zero cost. The overall allowance is quoted on net weight, the same basis as the allowance entered on each line. The material budget in Settings is optional; when set, the verdict compares the priced total with it, and the allowance warning level flags lines whose allowance is above it.

Density reference

Library values are standard handbook densities for the common condition of each grade. If your material certificate gives another value, enter it in the density override — it replaces the library figure for that line only.

• Material — kg/m³ — lb/in³
• Carbon & alloy steel
• Mild steel (A36 / 1018) — 7,850 — 0.2836
• 1045 medium-carbon steel — 7,850 — 0.2836
• 4140 alloy steel — 7,850 — 0.2836
• 4340 alloy steel — 7,850 — 0.2836
• O1 tool steel — 7,810 — 0.2822
• D2 tool steel — 7,700 — 0.2782
• Gray cast iron — 7,200 — 0.2601
• Stainless steel
• 303 stainless — 8,000 — 0.2890
• 304 / 304L stainless — 8,000 — 0.2890
• 316 / 316L stainless — 8,000 — 0.2890
• 410 stainless — 7,750 — 0.2800
• 17-4 PH stainless — 7,800 — 0.2818
• Aluminium
• 6061-T6 aluminium — 2,700 — 0.0975
• 7075-T6 aluminium — 2,810 — 0.1015
• 2024-T3 aluminium — 2,780 — 0.1004
• 5052 aluminium — 2,680 — 0.0968
• A356 cast aluminium — 2,670 — 0.0965
• Copper alloys
• C110 copper — 8,940 — 0.3230
• C360 free-machining brass — 8,500 — 0.3071
• C932 bearing bronze — 8,930 — 0.3226
• C172 beryllium copper — 8,250 — 0.2981
• Titanium & high-temperature alloys
• Titanium Grade 2 (CP) — 4,510 — 0.1629
• Ti-6Al-4V (Grade 5) — 4,430 — 0.1600
• Inconel 718 — 8,190 — 0.2959
• Inconel 625 — 8,440 — 0.3049
• Monel 400 — 8,800 — 0.3179
• Hastelloy C-276 — 8,890 — 0.3212
• Other metals
• Magnesium AZ31B — 1,770 — 0.0639
• Zinc — 7,135 — 0.2578
• Lead — 11,340 — 0.4097
• Tungsten — 19,300 — 0.6973
• Engineering plastics
• Acetal / Delrin (POM) — 1,410 — 0.0509
• Nylon 6/6 — 1,150 — 0.0415
• PTFE — 2,200 — 0.0795
• PEEK — 1,320 — 0.0477
• UHMW-PE — 930 — 0.0336
• Polycarbonate — 1,200 — 0.0434
• Acrylic (PMMA) — 1,180 — 0.0426
• HDPE — 950 — 0.0343
• PVC (rigid) — 1,400 — 0.0506
• G10 / FR4 glass epoxy — 1,850 — 0.0668

Pricing guidance

The calculator deliberately loads no market price. Enter the price from your supplier quotation, purchase order or approved internal material table — per kilogram in metric, per pound in imperial. Prices vary with alloy, product form, size, quantity, certification, processing, freight and location, so sheet, plate, bar and tube of the same grade can carry different prices. Add alloy surcharges, cut charges and minimum-order charges where they apply. The currency set in Settings is a label; nothing is converted between currencies.

Buying allowances: scrap, kerf and drop

You almost never buy exactly the finished weight. The allowance adds a percentage to reflect what you purchase:

• Kerf — material destroyed by the cut. A saw removes 2–3 mm per cut; plasma and oxy-fuel more; laser and waterjet 0.1–1 mm.
• Drop — the unusable end of a stock length. Six 900 mm parts from a 6 m bar leave a 600 mm drop, about 10% of the bar.
• Facing and clean-up stock — machining allowance on each end, skin cuts on plate.
• Nesting yield — on sheet and plate, part area over sheet area. 70–85% is common for irregular profiles.

Typical planning values are 3–5% for simple saw-cut bar, 8–15% for multi-part bar jobs with drops and 15–30% for nested plate. Bar and tube commonly come in 3 m and 6 m lengths; sheet in 1,220 × 2,440 mm and 1,524 × 3,048 mm.

Accuracy: theoretical against actual weight

• Mill tolerance: plate is usually rolled heavy within its thickness tolerance and often weighs 2–5% more than theoretical; structural sections are commonly allowed about ±2.5% on weight.
• Sharp corners: the angle, channel, beam and tee formulas ignore fillet radii and flange taper — use the mill's section tables for certified structural take-offs.
• Pipe: pipe is specified by nominal size and schedule, not its true outside diameter. Enter the actual OD and wall from a pipe chart, for example 48.3 mm × 3.68 mm.
• Coatings: galvanizing adds roughly 3–6% to steel weight.

For legal-for-trade or certified lifting weights, weigh the material.

Unit conversions used

The unit system in Settings governs every line. Entered numbers are read in that system, so changing it does not convert lines already typed — choose one system per cut list.

Saving your work

Lines, settings and the report header are kept in this browser's local storage as you type. Treat Export .json as the real save; Import .json restores it anywhere. Export CSV gives a spreadsheet-ready cut list for quotes and purchase orders, and the Executive report prints the totals, charts, bill of material and recommended actions.