Short answer: The smallest detail you can reliably laser cut in acrylic is about as wide as the sheet is thick. In 1/8 in. (3 mm) acrylic, that means holes, slots, and bridges of about 1/8 in.; in 1/4 in. (6 mm), about 1/4 in. The beam itself is far finer, about 0.004 to 0.007 in. across, so the limit is heat and handling, not the laser. Smaller features can be cut but tend to melt, distort, or snap. For text under about 3/8 in. tall, engrave it instead of cutting it out.
Key facts
- Beam size: a focused CO2 spot is about 0.004 to 0.007 in. with a standard 2 in. lens, and 0.003 to 0.0065 in. with a 1.5 in. fine-detail lens (Epilog).
- Practical minimum for cut features: about the sheet thickness, so 1/8 in. in 1/8 in. sheet and 1/4 in. in 1/4 in. sheet. This is a fabricator's rule of thumb, not a published standard.
- Engraving detail: far finer than cutting. Text reads down to about 6 to 8 pt.
- Kerf: about 0.006 to 0.010 in., so a gap you draw narrower than that disappears.
- Heat-affected zone: lab measurements on 3 mm acrylic found 0.35 to 0.44 mm (about 0.014 to 0.017 in.) of heat-affected material beside the cut. Two cuts closer together than about 1/32 in. overlap their heat zones.
The thickness rule of thumb
A laser beam is only a few thousandths of an inch wide, so the limit isn't the beam. It's the acrylic. Every cut puts heat into the sheet, and a thin piece of material between two cuts has nowhere to shed that heat. It softens, sags, or melts into a blob. Even if it survives cutting, a sliver of acrylic thinner than it is deep is fragile and snaps the first time it's bumped.
So the working guideline is: no feature narrower than the sheet thickness. You can push below that in places, but results get less predictable. Sheet makers don't publish a minimum feature size. Perspex says its cast sheet can be laser cut into very complex, intricate shapes, but the safe minimum comes from experience on the cutting table, and that's where this rule comes from.
Minimum sizes for 1/8 and 1/4 in. acrylic
| Feature | 1/8 in. (3 mm) | 1/4 in. (6 mm) |
|---|---|---|
| Round hole, comfortable | 1/8 in. diameter | 1/4 in. diameter |
| Round hole, possible but less clean | About 1/16 in. | About 1/8 in. |
| Slot width | 1/8 in. | 1/4 in. |
| Bridge or web between cuts | 1/8 in. minimum, 3/16 in. better | 1/4 in. minimum, 3/8 in. better |
| Gap between parts on the sheet | At least 1/8 in. | At least 1/4 in. |
| Cut-out text, cap height | About 3/8 in. and up | About 1/2 in. and up |
| Engraved text, cap height | About 1/16 in. (roughly 6 pt) and up | Same |
These are typical starting points, not hard limits. Shape matters: a short, thick bridge holds up better than a long, thin one, and a cluster of small holes close together heats up more than one hole alone.
Why small holes come out less clean
With a small hole, the laser spends a lot of time in a tiny area. The inside walls melt more, the hole can come out slightly oval or tapered, and the plug of waste can re-weld itself in place. In 1/4 in. sheet, holes much under 1/8 in. are also hard to get clean all the way through. If you need a small, precise hole for a pin or screw, it's often better to cut it a bit undersize and drill it out, or drill it from the start.
Thin bridges and delicate shapes
Filigree, script lettering, snowflakes, and lace patterns are where acrylic gets tested hardest. Watch for:
- Long, thin arms. A leg of a script letter that's 1/16 in. wide and 2 in. long will break in 1/8 in. sheet. Thicken it or shorten it.
- Points where shapes barely touch. If two letters connect at a single point, that point will either melt through or snap. Make the overlap at least the sheet thickness wide.
- Sharp inside corners at thin sections. These concentrate stress. A small radius helps.
For cake toppers and script names, 1/8 in. acrylic with letter strokes at least about 1/8 in. wide is a good balance (acrylic cake toppers).
Stencil fonts and floating islands
When you cut letters out of a panel (a stencil), the centers of letters like O, A, B, D, P, Q, and R have nowhere to attach and fall out. You have three options:
- Use a stencil font, which has built-in bridges holding the centers.
- Add your own bridges at least the sheet thickness wide.
- Engrave the letters instead of cutting them through.
More on fixing this in artwork in how to convert an image to SVG for laser cutting. For stencil projects, see acrylic stencils.
Cutting vs engraving tiny text
Engraving removes only a thin layer of the surface, so it doesn't weaken the part and can show far finer detail than cutting. Engraved text reads well down to roughly 6 to 8 pt, and fine lines and logos hold up well. If your text is smaller than about 3/8 in. tall, engrave it. See laser engraving acrylic: what to expect.
Thicker isn't always stronger for detail
It's tempting to go thicker to make delicate parts stronger, but the minimum feature size grows with thickness. A design that works in 1/8 in. may have bridges that are too thin in 1/4 in., and it will cut with more taper. If you want fine detail, thinner sheet is usually the better choice.
Not sure if your design will survive?
Run it through our laser file checker to see size and cut length, then upload it for a quote. If we see a feature that's likely to break, we'll tell you before we cut.
Questions
What is the smallest hole a laser can cut in acrylic?
Holes down to about 1/16 in. are possible in 1/8 in. sheet, but they're less round and clean. For reliable results, keep holes at least as wide as the sheet is thick.
What's the minimum bridge width in 3 mm acrylic?
About 3 mm is a safe minimum, and 4 to 5 mm is better for long or handled parts. Short bridges can sometimes go a little thinner.
What's the smallest text you can laser cut out of acrylic?
For cut-out letters, aim for capitals about 3/8 in. tall in 1/8 in. sheet and 1/2 in. in 1/4 in. sheet, with strokes at least as wide as the sheet is thick. Anything smaller is better engraved, which holds detail down to about 6 to 8 pt.
Does a smaller lens give finer cut detail?
A short 1.5 in. lens makes a smaller spot (0.003 to 0.0065 in., per Epilog), which helps fine engraving and thin material under 1/16 in. It doesn't change the real limit for cut features, which is how much heat a thin sliver of acrylic can take.
Is fine detail different in mirror or colored acrylic?
The same rules apply. Mirror acrylic's backing can show heat effects on very fine features, so give it a little extra width.