PHOTO PREPARATION GUIDE · RASTERGO
Image size in millimetres to pixels for laser engraving
Updated October 2026 · Free browser tool · photos stay on your device
Pixels per side = round(millimetres ÷ 25.4 × DPI). Set the physical size and DPI before editing tones, and always confirm the size again after importing into your laser software.
The formula
pixels = round(mm ÷ 25.4 × DPI)
For 100 mm at 300 DPI: round(100 ÷ 25.4 × 300) = 1181 pixels per side.
Worked table
| Physical size | 250 DPI | 300 DPI | 500 DPI |
|---|---|---|---|
| 50 × 50 mm | 492 px | 591 px | 984 px |
| 100 × 100 mm | 984 px | 1181 px | 1969 px |
| 150 × 150 mm | 1476 px | 1772 px | 2953 px |
| 200 × 150 mm | 1969 × 1476 px | 2362 × 1772 px | 3937 × 2953 px |
Values are rounded to whole pixels; your software may round differently by one pixel.
Why set size before editing
Tonal work judged at screen scale is misleading: contrast and dithering that look right at 3000 px can collapse when the same image is placed at 591 px. Set size first, then adjust, then export once.
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