The calculator
Runs in your browser. Inches or millimetres at the top.
How the layout is found
Along one side, a sheet of length L takes floor((L − g) / (a + g)) blanks of length a with a gap g between them and at both edges. Rows times columns gives the grid.
The calculator tries the blank both ways round, then a grid in one orientation with the leftover strip filled by blanks turned 90°, along the length and across the width. It keeps whichever layout holds the most. It is not a full nesting optimiser; for rectangles of one size it is usually the best count, and never an optimistic one.
Grain direction is the reason to untick rotation. A bend parallel to the rolling direction cracks sooner than one across it; if the drawing fixes the grain, every blank must keep it.
Worked example
40 blanks of 10 × 6 in from a 48 × 144 in sheet, 1/8 in kerf and margin, rotation allowed.
- 10 in along the length: floor((144 − 0.125) / 10.125) = 14; 6 in across: floor((48 − 0.125) / 6.125) = 7. Grid: 98.
- Turned: floor(143.875 / 6.125) = 23 by floor(47.875 / 10.125) = 4. Grid: 92.
- Mixed: the turned grid (23 × 4 = 92) leaves a strip across the width of 48 − 0.125 − 4 × 10.125 = 7.375 in, which holds one row of 14 blanks the other way. Best layout: 106 per sheet, so 1 sheet for 40.
A 4 × 12 ft sheet holds 106. A 4 × 8 ft sheet holds 69 the same way and is enough: buy the smaller one.
Limits — when NOT to use this
- Rectangles only. Irregular flat patterns nest tighter than their bounding rectangles. Use this for ordering, not for the cutting program.
- Flat pattern first. The blank size is the developed length, not the finished part. Get it from the bend allowance calculator.
- Sheet sizes vary by supplier and alloy. Check the size you are actually quoted.
Questions people actually ask
What gap should I use?
Your saw or shear kerf plus whatever you trim to clean an edge. A shear has almost no kerf but needs a straight edge to register on; a router or bandsaw takes 1/16 to 1/8 in plus finishing.
Does the offcut count the unused room?
Yes. Offcut is the share of all the metal bought that does not become a blank you need, including the empty part of the last sheet.
Sources
- Geometry of the layout — the counts follow from the dimensions entered. The sheet presets are common stock sizes (4 × 8, 4 × 10 and 4 × 12 ft; 1000 × 2000, 1250 × 2500 and 1500 × 3000 mm); they are not a claim about any supplier's range.