Calculators
Nest rectangular and irregular parts on steel or aluminium plate, from a parts list or a DXF. Free, in the browser.
Sheet metal and plate are priced in a way that punishes carelessness. A sheet of 10 mm steel or 6 mm aluminium costs enough that the difference between 60 and 75 percent utilisation is real money on every single sheet, and scrap value returns only a fraction of it. So plate work gets nested. Parts are arranged together on the sheet, sharing the space, and the arrangement is chosen before anyone presses start on the machine.
The calculator takes your parts and your plate sizes and returns the nested layout, the plate count, and the position of every usable remnant. Common metric plates like 2500 x 1250 and 3000 x 1500 mm work alongside imperial sizes, and mixed plate sizes in one job are fine.
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There are two kinds of nesting, and knowing which one your job needs saves either money or effort. Rectangular nesting treats every part as its bounding box. For gusset blanks, flat bar work, brackets that get folded from rectangles, it is exactly right, and it is the fast path.
True shape nesting works with the real outline. Parts rotate to angles a person would never try, L shapes interlock, and small parts drop into the waste inside larger ones, the middle of a ring being the classic case. On irregular profiles the yield difference over bounding boxes is large, which is why profile cutters use it as a matter of course. Cutlist Evolution does both, and the nesting optimizer page covers the true shape side in depth.
One machine constraint decides some of this for you. A guillotine or shear can only make straight cuts from edge to edge, so guillotine work needs layouts built from full-width cuts. Lasers, plasma tables, routers and waterjets can follow any path, which is what makes true shape nesting possible in the first place. Tell the calculator which kind of cutting you are doing and the layouts respect it.
Profiles usually already exist as drawings, so the calculator imports parts from DXF files rather than asking you to retype geometry. Nested layouts export as DXF and SVG, ready for the post-processing software that drives the machine, with PDF diagrams for the paperwork.
Every cutting process removes material along the cut, and on thermal processes the kerf is wider than a saw operator expects. A laser cuts a narrower kerf than plasma, and the right value depends on the process, the nozzle and the plate thickness, so the calculator takes kerf as a setting rather than assuming one. Parts also need clear space between them, both for the kerf itself and because heat distorts thin plate when cuts run too close together. Set the part spacing once and every layout honours it.
Remnants deserve planning too. A layout that leaves one large clean rectangle at the end of the plate is worth more than one that leaves the same area as ragged edges, because a clean remnant goes back on the rack as stock. Offcuts can be fed into the next calculation, so the remnant rack turns over instead of accumulating.
Utilisation sounds like one number but hides two. Bounding-box utilisation counts the rectangle around each part as used, which flatters rectangular nests and says nothing useful about true shape work. Net utilisation counts only the part outlines themselves, and it is the number the material invoice responds to. When you compare layouts, compare like with like, and remember that the plate count is the figure that actually gets paid. A nest that raises utilisation by two points but still needs the same three plates has saved nothing except pride.
Nesting is bin packing under another name, and the bin packing problem article explains the approaches and their trade-offs. For wood-based sheet goods, where grain direction changes the rules, see the plywood cut calculator. For the general parts-list-to-diagram workflow, start at the cut sheet calculator.
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