Sheet metal cut calculator
Enter your sheet or coil and the blanks you need. The calculator lays the rectangles out with your gap and edge margin, then shows how many sheets the job takes, how much of the material is used and a layout to cut from. It is free and needs no account.
The calculator
How does the calculator lay parts out?
It treats every part as a rectangle and places the largest first, each one as close to one end of the sheet as it will go. With rotation allowed, a part is turned 90° whenever that keeps the layout shorter. The gap you enter is kept between every pair of parts, and the edge margin is kept clear all the way round the sheet.
A laser, plasma table or waterjet can cut any layout, so by default the parts are packed as tightly as they will go. A shear or a saw can only cut straight across from edge to edge. Tick "Straight cuts only" and every layout can be cut that way: first into strips across the sheet, then each strip into parts.
The unused material ends up at the far end of the last sheet as one offcut across the full width, which is the piece worth putting back on the rack. For a coil, the calculator reports the length the job takes off the roll.
What gap should you leave between parts?
The gap covers two things: the kerf, which is the width of material the cut removes, and any web you leave so the sheet stays in one piece while it is cut. These are typical kerf widths; use the figure from your own machine's cutting chart.
| Process | Typical kerf |
|---|---|
| Shear | None |
| Fibre laser | 0.1 to 0.4 mm (0.004 to 0.016 in) |
| CO2 laser | 0.2 to 0.5 mm (0.008 to 0.020 in) |
| Waterjet | 0.8 to 1.3 mm (0.03 to 0.05 in) |
| Plasma | 1.5 to 4 mm (0.06 to 0.16 in) |
What are the standard sheet sizes?
North American mills and service centres stock sheet in feet; most of the rest of the world stocks it in metric formats. The calculator has these six built in, and takes any other size you type.
| Sheet size | Converts to |
|---|---|
| 48 × 96 in (4 × 8 ft) | 1219 × 2438 mm |
| 48 × 120 in (4 × 10 ft) | 1219 × 3048 mm |
| 60 × 120 in (5 × 10 ft) | 1524 × 3048 mm |
| 1000 × 2000 mm | 39.4 × 78.7 in |
| 1250 × 2500 mm | 49.2 × 98.4 in |
| 1500 × 3000 mm | 59.1 × 118.1 in |
How do you turn a layout into material cost per part?
Multiply the number of sheets by the price of a sheet, then share that total across the parts by area. The scrap is paid for either way, so it belongs in the part price. Type a cost per sheet into the calculator and it does this for each part in the list.
Material is one line of a sheet metal quote. Cutting time, bending, hardware and finishing are the others, and this guide to sheet metal quoting walks through each of them. OneThou reads the blank, the material and the gauge from the customer's PDF drawing and drafts the whole quote on your shop's own rates.
Questions about the cut calculator
How many parts fit on a 4 × 8 sheet?
It depends on the blank size, the gap you leave between parts and the border you keep clear at the edge. Enter the blank's length, width and quantity above and the calculator shows how many fit on each 48 × 96 inch sheet and draws the layout. To check by hand, divide the usable sheet length and the usable width by the blank size plus the gap, round each down, and multiply the two.
What gap should I leave between parts?
Enter the width your cutting process removes plus any web you leave between parts. A shear removes nothing. A fibre laser removes a few tenths of a millimetre, a waterjet about a millimetre, and plasma from about 1.5 mm up, depending on the nozzle and the thickness. Many shops keep the gap at least as wide as the sheet is thick, so the skeleton holds together while it is cut.
Can it nest irregular outlines?
No. It lays out rectangles. That suits sheared blanks, and it gives a safe material figure for a part cut inside its bounding rectangle. True-shape nesting in a laser or punch programming package will usually fit more parts on the sheet.
What if grain direction matters?
Untick "Parts can turn 90°". Every part then keeps its length along the length of the sheet or coil, which is normally the rolling direction.
Is the layout the best possible one?
It is a good layout, not a guaranteed best. The calculator tries several packing orders and keeps the one that uses the fewest sheets and leaves the largest offcut on the last sheet. Check the drawing before you cut.
Does the calculator save or send my parts list?
No. The layout is worked out in your browser, and nothing you type into the calculator is sent anywhere.
Need the weight or the cost of the sheet? Use the metal weight and cost calculator, or look up a thickness in the gauge chart. More are on the tools page.
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