LightBurn Settings Guide: Speed, Power & Passes Explained (2026)
LightBurn is the most widely used laser control software, supporting both GRBL-based diode lasers and DSP-controlled CO2 machines. Getting the right combination of speed, power, and passes is the difference between a clean cut and a charred mess. This guide explains every key setting, how they interact, and gives you starting points for common materials.
Understanding the Key Settings
01Speed (mm/s or mm/min)
Speed controls how fast the laser head moves across the material. Slower speeds deliver more energy per unit area, producing deeper cuts and darker engravings. Faster speeds deliver less energy, resulting in lighter marks.
Unit conversion
LightBurn uses mm/min for GRBL machines and mm/s for DSP controllers by default. To convert: mm/s × 60 = mm/min. So 10 mm/s = 600 mm/min. You can change the display unit in Edit > Settings > Display & Units.
02Power (%)
Power sets the laser output as a percentage of maximum. LightBurn has two power settings: Max Power (used during normal movement) and Min Power (used during acceleration and deceleration at corners). For most operations, set Min Power 5-10% below Max Power to maintain consistent energy delivery through direction changes.
03Passes
Passes define how many times the laser repeats the same path. Multiple passes are used when the laser does not have enough power to cut through material in a single pass. Each pass adds to the total cut depth. For engraving, always use 1 pass and adjust power instead.
04Lines per Inch (DPI) / Line Interval
DPI and line interval control the resolution of raster (Scan) engraving. They are inversely related: Line Interval = 25.4 ÷ DPI. Higher DPI means finer detail but longer job times. Common values:
| DPI | Line Interval | Use Case |
|---|---|---|
| 150 | 0.169mm | Fast drafts, low detail |
| 254 | 0.100mm | Standard quality — recommended starting point |
| 318 | 0.080mm | High detail for photos and fine text |
| 508 | 0.050mm | Maximum detail — CO2 lasers with small beam spot |
05Air Assist
Air assist is not a LightBurn setting per se, but it dramatically affects the results you get from any speed/power combination. Compressed air at the cutting point removes smoke from the beam path (improving energy delivery), blows away combustion byproducts (reducing charring), and cools the material (reducing fire risk). Research data shows that air assist can improve effective cutting depth by 20-40% at the same speed and power settings.
How Speed and Power Interact
Speed and power are inversely related in terms of their effect on the material. Doubling the speed has roughly the same effect as halving the power—both reduce the total energy delivered to a given point on the material.
The total energy delivered to a point is proportional to Power ÷ Speed. This means there are many valid combinations for any operation. A 50% power, 500 mm/min combination delivers similar energy to a 100% power, 1000 mm/min combination.
Rule of Thumb
- •For cutting: Use high power (80-100%) and adjust speed to control depth. Fewer passes at higher power produce cleaner edges than many passes at lower power.
- •For engraving: Use moderate speed (2000-6000 mm/min for GRBL) and adjust power to control darkness/depth. Lower power gives lighter, more controlled marks.
- •For scoring: Use moderate speed and low power (10-30%). The goal is to mark the surface without cutting through.
Recommended Starting Settings by Material
These are starting points for a 20W diode laser unless noted otherwise. Always test on scrap material first. Click a material name for a detailed settings page.
| Material | Operation | Speed | Power | Passes | Notes |
|---|---|---|---|---|---|
| 3mm Plywood | Cut | 200–400 mm/min | 80–100% | 1–2 | 20W diode with air assist. Reduce speed for 10W. |
| 3mm Plywood | Engrave | 3000–6000 mm/min | 20–40% | 1 | Lower power for lighter engraving. 254 DPI works well. |
| 3mm Acrylic (dark) | Cut | 150–300 mm/min | 90–100% | 2–3 | Diode laser on dark/black acrylic only. CO2 for clear. |
| 3mm Acrylic (clear) | Cut | 8–15 mm/s | 60–80% | 1 | CO2 laser only. 40W+ recommended. |
| Vegetable-Tanned Leather | Engrave | 3000–5000 mm/min | 15–30% | 1 | Start low — leather darkens quickly. Test first. |
| Vegetable-Tanned Leather | Cut (2mm) | 200–400 mm/min | 70–90% | 1–2 | Use air assist. Watch for flame on thicker leather. |
LightBurn Layer Settings Explained
LightBurn uses color-coded layers to organize different operations within a single job. Each layer can have its own mode, speed, power, and pass settings. Understanding the three primary modes is essential.
Line (Cut) Mode
Line mode traces vector paths with the laser on. This is used for cutting through material and for single-line engraving (like text outlines or fine detail work). The laser follows the exact path of your vectors. Speed and power together determine whether the laser cuts through or just scores the surface.
Fill (Scan) Mode
Fill mode rasters enclosed areas with back-and-forth horizontal passes. This is how you engrave images, fill text, or create shaded areas. The DPI / line interval setting controls resolution. The laser scans left-to-right (or right-to-left), steps down by the line interval, and scans the next line. This is the most common mode for engraving.
Offset Fill Mode
Offset Fill traces concentric inward paths to fill a shape, following the contour of the outline rather than scanning horizontally. It produces a different visual effect than standard Fill and can be useful for organic shapes. It is slower than Fill for large areas but produces smoother results on curved shapes.
Common LightBurn Mistakes
#1Confusing mm/s with mm/min
LightBurn defaults to mm/min for GRBL machines and mm/s for DSP controllers. A speed of "300" means completely different things depending on the unit. 300 mm/s = 18,000 mm/min.
Check your speed unit in Edit > Settings > Display. Convert by multiplying mm/s by 60 to get mm/min, or dividing mm/min by 60 to get mm/s.
#2Running at 100% power for engraving
Maximum power is meant for cutting. Using 100% power for engraving will burn through the material, create excessive charring, and wear out your laser module faster.
Start engraving at 15-30% power and increase in 5% increments. Most wood engraving looks best at 20-40% power.
#3Skipping material tests
Every piece of material is different. Plywood brands vary in density, glue type, and moisture content. Settings that work on one sheet may burn through or barely mark another.
Run a small test grid (speed vs power matrix) in an unused corner before committing to a full job. LightBurn has a built-in material test generator.
#4Setting DPI too high for engraving
Higher DPI does not always mean better quality. Above 300 DPI, most diode lasers produce diminishing returns because the beam diameter cannot resolve finer detail. Higher DPI also dramatically increases job time.
Use 254 DPI (0.1mm line interval) as a starting point. Go to 318 DPI for fine detail. Only go higher on CO2 lasers with small beam spots.
#5Forgetting to enable air assist for cuts
Cutting without air assist produces more charring, increases fire risk, and contaminates the lens with smoke residue. Air assist is not optional for cutting — it is essential.
Always enable air assist when cutting. Even a low-pressure aquarium pump makes a measurable difference in cut quality and lens longevity.
#6Not focusing the laser before each job
An out-of-focus laser produces a wider beam, reducing both cutting power and engraving detail. Even a 1-2mm focus error makes a noticeable difference.
Use the focus gauge or auto-focus before every job. Re-check focus when changing material thickness. The focus distance is measured from the lens to the material surface.
How to Test Your Settings
Testing before committing to a full job saves material, time, and frustration. Follow this procedure for every new material or whenever you change your setup.
- 1
Create a test grid
Use LightBurn's built-in Material Test generator (Laser Tools > Material Test) to create a grid that varies speed on one axis and power on the other. A 5x5 grid covering your expected range is usually sufficient.
- 2
Prepare test material
Cut a small piece of your actual material (not a different brand or batch). Place it in the center of the work area where the laser performs most consistently.
- 3
Focus the laser
Use the focus gauge or auto-focus to set the correct focal distance. This step is critical — an out-of-focus test produces invalid results.
- 4
Enable air assist
If you use air assist for your final projects, enable it during testing too. Air assist significantly affects results, so testing without it and running with it produces different outcomes.
- 5
Run the test
Execute the test grid. Wait for it to finish completely before evaluating results — some effects (like through-cuts) only become visible after the material cools.
- 6
Evaluate and record
Identify the speed/power combination that produces the best result. For cuts, check if the material separates cleanly. For engraving, look for the desired contrast level. Write down the winning settings or save them as a LightBurn material library entry.
- 7
Run a final confirmation
Cut or engrave a small sample using your chosen settings on the actual project material. Confirm the result matches your test before running the full job.
Frequently Asked Questions
- What speed should I use for laser cutting in LightBurn?
- Cutting speeds depend on material, thickness, and laser power. For a 20W diode laser cutting 3mm plywood, start at 200-400 mm/min at 80-100% power. For a 40W CO2 laser cutting 3mm acrylic, start at 8-15 mm/s at 60-80% power. Always run a test cut on scrap material before your final piece.
- What is the difference between Cut, Scan, and Score in LightBurn?
- Cut mode follows vector paths with the laser on, used for cutting through material or making single-line marks. Scan mode fills enclosed areas with back-and-forth passes (raster engraving), used for images and filled text. Score mode traces vector paths at lower power without cutting through, used for detail lines and fold marks.
- How do I convert DPI to line interval in LightBurn?
- Line interval = 25.4 / DPI. For example: 254 DPI = 0.1mm line interval, 318 DPI = 0.08mm line interval, 508 DPI = 0.05mm line interval. In LightBurn, you can enter either value and the other updates automatically. For most diode lasers, 254 DPI (0.1mm) is a good starting point.
- Should I use multiple passes or more power?
- For cutting, higher power with fewer passes generally produces cleaner results and less charring than multiple passes at lower power. Multiple passes work better when your laser does not have enough power to cut in one pass, or when cutting thick material where heat buildup is a concern. For engraving, always use a single pass with adjusted power.
- Why does my LightBurn engraving look different on different materials?
- Each material absorbs laser energy differently. Dark materials absorb more energy, so they need less power. Light materials reflect more of the diode wavelength. Grain direction in wood affects how the laser interacts with the surface. Always test settings on each new material, and use LaserParams to get starting parameters specific to your machine and material combination.
Get Custom Settings for Your Machine
Tell our AI assistant your machine model and what you want to cut or engrave. It will give you the exact LightBurn speed, power, and pass settings to start with—calibrated for your specific setup.
Try the AI Laser Assistant