What DPI (Lines per Inch) Should You Use for Laser Engraving?
For most wood engraving, 254 DPI (a line interval of 0.1 mm) is a good default. Photos on a CO2 laser can use 318–500 DPI (0.08–0.05 mm), while bold fills on a diode often look best at 127–200 DPI. The right value matches your laser spot size: finer than the spot does not add detail.
You open the engraving settings and see a number: 254, 300, 500, or 0.1 mm. You change it, run the job and the result gets either beautiful or painfully slow. What DPI should you actually use?
For wood, start at 254 DPI, which is a line interval of 0.1 mm. That is the standard, and it works for most diode and CO2 lasers. Go finer for photos on a CO2, coarser for fast fills and deep texture.
DPI here means the number of scan lines per inch, also written LPI. The line interval is just the distance between those lines: interval (mm) = 25.4 divided by DPI.
DPI to line interval conversion
| DPI (LPI) | Line interval (mm) | Typical use |
|---|---|---|
| 100 | 0.254 | Very coarse, texture, fast |
| 127 | 0.20 | Fast fills, bold shapes |
| 169 | 0.15 | Quick engraving, deep relief |
| 254 | 0.10 | General wood engraving |
| 318 | 0.08 | Photos, fine detail on CO2 |
| 400 | 0.064 | High detail on a fine-spot CO2 |
| 500 | 0.05 | Very fine work, small spot only |
Match DPI to your laser spot
The line interval should be close to your spot size. A diode with a 0.1–0.2 mm spot looks fine at 0.1 mm, and going to 0.05 mm just overlaps the lines. A well-focused CO2 with a spot around 0.1 mm or smaller can resolve 0.08 mm.
| Laser | Typical spot size (roughly) | Good interval for detail |
|---|---|---|
| Diode 5–10 W | 0.1–0.2 mm | 0.1 mm |
| Diode 20 W | 0.1–0.2 mm | 0.1 mm |
| CO2 40–100 W | 0.1–0.2 mm | 0.08–0.1 mm |
Spot sizes depend on the lens and focus, so use these as rough guidance only. Focus matters: see how to focus a laser.
A worked example
You engrave a 100 × 100 mm block of shading. At 0.1 mm interval that means 1000 lines. If the head moves at 100 mm/s, each line takes about 1 second, plus turnaround, so roughly 17–20 minutes. At 0.2 mm interval, it is half as many lines and about 9–10 minutes. For a bold logo, the faster setting is often fine. For a photo of a face, the finer interval is worth the time.
Pro tip: If time matters, test at 0.15 mm first. Many designs look almost the same as at 0.1 mm and cut the time by a third.
Factors that change the best DPI
- Speed: higher DPI with high speed can leave lines faint, so power and speed must be adjusted together, see speed and power for engraving wood.
- Material: soft wood shows fine lines easily, plywood with varied grain hides them.
- Image: photos need dithering and fine lines, line art does not.
- Machine: belts and vibration can limit the real resolution at high speed.
Common mistake: Choosing a very high DPI like 1000 because it sounds better. The laser spot is far bigger than that, so you get overburn and long run times with no extra detail.
Photos and image mode
For photo engraving, prepare the image first: grayscale, adjusted contrast, then dithered by the software (Jarvis, Stucki or similar). See how to turn an image into a laser file. Use 254–318 DPI on wood and test on scrap before you commit the real piece.
Quick recommendations
| Job | DPI | Interval |
|---|---|---|
| Bold logo, big letters | 127–170 | 0.15–0.2 mm |
| Text and line art on wood | 254 | 0.1 mm |
| Photo on plywood, diode | 254–318 | 0.1–0.08 mm |
| Photo on basswood, CO2 | 318–400 | 0.08–0.064 mm |
Start in the middle, check the sample, and move one step either way. Always test on scrap.
Questions and answers
What is the difference between DPI, LPI and line interval?
For laser engraving they describe the same thing: how closely the scan lines are spaced. Line interval is the distance in mm, and DPI or LPI is lines per inch. Interval in mm = 25.4 divided by DPI.
Is higher DPI always better?
No. If the interval is smaller than the laser spot, the lines overlap, the engraving gets darker and the job takes longer without more detail.
What DPI do I use for photos?
On CO2, about 318–400 DPI (0.08–0.064 mm). On diodes, usually 254–318 DPI, because the spot is typically larger.
Does DPI change the engraving time?
Yes. Doubling the DPI doubles the number of scan lines, so the time roughly doubles.
What should I do if I see stripes?
The interval may be wider than the spot, or the focus is off. Reduce the interval or refocus, and check for belt tension problems.
Does image resolution matter too?
Yes. Make sure the image has enough pixels for the size you engrave. About 254–300 pixels per inch at the final size is plenty for wood.