Laser Material Test Generator
Make a power-and-speed test card for any material, then download ready-to-run GRBL G-code or a printable SVG card.
Test card results
5 × 5 grid · 62 × 62 mm · ≈ 19.2 min laser-on
(travel and acceleration not included)
For GRBL 1.1 controllers with laser mode on ($32=1), sent with a G-code sender (for example LaserGRBL). If your laser uses a Ruida/Trocen-type controller or a cloud app, it cannot run this file — use the SVG card with your software's own test tool instead.
Results are starting points, not guarantees. Lasers can start fires and damage eyes — follow your machine’s safety instructions and never leave a running laser.
Quick answer
A material test card burns a grid of small squares, each at a different power (columns) and speed (rows), so you can see which combination gives the result you want on that exact material. This generator writes the G-code for GRBL laser controllers, orders the squares from the gentlest to the strongest so you can stop early, and gives you an SVG card to record the winner.
How to use this generator
- Put the material on the bed and focus the laser as you normally do.
- Choose the power range (columns) and speed range (rows). Keep the cells small to save material.
- Download the G-code, open it in your G-code sender and use its frame/preview function to check the area.
- Move the laser head to the bottom-left corner of where the grid should go and start the job. Stay with the machine.
- Pick the best-looking square and enter its row and column below the preview to get its exact settings.
Worked example
With the default settings (5 × 5 grid, power 20–100 %, speed 600–3000 mm/min, $30 = 1000):
- Columns are 20 %, 40 %, 60 %, 80 % and 100 % (S200 to S1000).
- Rows are 600, 1200, 1800, 2400 and 3000 mm/min.
- The first square to burn is 20 % at 3000 mm/min — the lowest energy.
- The grid measures 62 × 62 mm and needs about 19.2 minutes of laser-on time (travel not included).
How it’s calculated
- Power steps and speed steps are spaced evenly between your lowest and highest values.
- The S value is power % × your
$30value ÷ 100, rounded to a whole number. - Squares run in order of power ÷ speed, lowest first. LightBurn’s built-in material test uses the same safety idea: highest speed and lowest power first.
- Filled squares are engraved as back-and-forth lines spaced by the line interval. The G-code uses relative moves (
G91), so the job starts wherever the laser head is. - G0 travel moves never fire the laser in GRBL laser mode (GRBL documentation).
Frequently Asked Questions (FAQ)
What is a laser material test card?
A grid of small squares burned at different power and speed settings on the material you plan to use. It shows, on your machine, which setting gives the depth and color you want.
What settings should I use for wood, acrylic, leather or slate?
There is no setting that works on every machine: the same numbers behave differently with different lasers, lenses, focus and materials. Use your manufacturer's suggested settings as a starting range, run a test card, and keep the winner.
Why does the test start with the weakest square?
So you can stop the job early if a gentle square already cuts through or scorches, instead of finding out on the strongest square.
Will this G-code work with my laser?
It is written for GRBL 1.1 controllers with laser mode enabled ($32=1). Many desktop diode lasers use GRBL-based controllers; check your manual. It does not work on controllers that need their own file format.
What is the difference between M4 and M3?
In GRBL laser mode, M4 changes power with the machine's actual speed (less power while accelerating), which avoids dark spots at corners; M3 keeps power constant. M4 is the default here.
How do I find my $30 value?
Send $$ in your G-code sender and read the $30= line. If the value is wrong, every power level in the test will be wrong.
I use LightBurn — do I need this?
LightBurn has its own Material Test tool. You can still use the SVG card here to print or keep a record of your results, and the converter to move a known setting to another machine.
Sources
- GRBL v1.1 Laser Mode (GRBL wiki)
$32=1, M3 vs M4, G0 never fires laser, safety warning
- GRBL v1.1 Configuration (GRBL wiki)
$30 max S value, linear S→PWM mapping
- LightBurn — Material Test
run order "highest speed, lowest power first"; unit warning
Last reviewed: 2026-10-26
Built and maintained by Numberwright. Every formula on this page is listed under “How it’s calculated”, with its sources. Found a mistake? Contact details coming soon.
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