LaserCanvas
Laser classes 1 to 4, and which one you own
Classes run 1 (safe in normal use) to 4 (hazardous to eyes and skin, and a fire risk, even from scattered light). Every laser that cuts is Class 4 inside. A fully enclosed machine with working interlocks is a Class 1 product — the enclosure, not the beam, is what makes it safe. If you are not trained in laser safety, buy a Class 1 machine. An open-frame laser puts the entire safety burden on you, and many budget machines sold online are exactly that.
What a class describes
The classification in IEC 60825-1 describes how dangerous the accessible radiation is, not how powerful the machine is. It accounts for wavelength, power, pulse structure and how long you could plausibly be exposed before you react. A class is assigned to a product as it is sold, in its normal operating state.
The classes
| Class | Means | Typical example |
|---|---|---|
| 1 | Safe in normal use, including for the eye. Either very low power, or a higher-power laser fully enclosed | CD player; an enclosed laser cutter with interlocks |
| 1M | Safe unless you view it with magnifying optics | Some fibre-optic sources |
| 2 | Visible light only, ≤1 mW. The blink reflex is considered protection | Barcode scanner, laser pointer |
| 2M | As Class 2, unless viewed through optics | Some alignment lasers |
| 3R | Up to 5 mW. Risk is low but the blink reflex is no longer relied on | Stronger pointers, some alignment tools |
| 3B | 5–500 mW. Direct viewing is hazardous; diffuse reflections generally are not | Laboratory lasers, some engravers |
| 4 | Over 500 mW. Hazardous to eyes and skin, including from scattered light, and a fire hazard | Every laser that cuts material |
Why your cutter is Class 4
Cutting requires enough energy to vaporise material. A 5 W optical diode is ten times the Class 3B ceiling; a 50 W CO2 tube is a hundred times it. There is no such thing as a Class 2 laser cutter, and a machine advertised as safe because it is "only 5 watts" is describing a Class 4 source.
- Diffuse reflection is hazardous at Class 4. You do not need to look into the beam. Light scattered off the material, the bed or a clamp can damage your retina.
- Skin damage is possible, not only eye damage.
- It will start fires, which is why fire risk is part of the definition rather than a separate concern.
How an enclosure changes the class
A machine whose beam cannot escape during normal operation can be classified as a Class 1 product with an embedded Class 4 laser. That is not a marketing trick; it is the correct description, and it is why an enclosed machine can sit in a classroom.
It depends entirely on the enclosure doing its job:
- Interlocks that actually cut the beam when the lid opens. Test yours — open the lid mid-job and confirm it stops.
- A window rated for the wavelength. Orange acrylic blocks CO2 and many diode wavelengths; plain clear acrylic does not block a diode’s blue light.
- No gaps at cable entries or the passthrough slot.
The moment you defeat an interlock to watch a cut, the product is Class 4 again and you are standing in front of it.
Open-frame machines
A large share of budget machines — particularly those sold through online marketplaces and shipped direct — arrive as an open frame: a gantry, a module, no box. These are Class 4 products, and they are routinely bought by people who have not been told that. The listing says "laser engraver" and shows it on a kitchen table; nothing in the box explains that the safety an enclosure would have provided is now entirely their responsibility.
The tinted shield clipped to the laser module is a convenience for looking at the work. It is not an enclosure, it does not contain scattered light in the room, and it does nothing about fire. Nor are the goggles usually supplied with such machines: they are often unmarked, unrated, and give no stated protection at any wavelength.
If you already own one, the options in order of effectiveness:
- Build or buy an enclosure. It solves scattered light, fume containment and fire containment in one object.
- Wear rated eyewear whenever the machine can fire — not only when you are looking at it.
- Keep other people and pets out of the room. They are not wearing eyewear and do not know to look away.
- Never leave it running unattended. Class 4 means fire is part of the definition.
Eyewear has to match the wavelength
Laser safety glasses are wavelength-specific. Glasses that protect against a 450 nm diode do nothing against a 10,600 nm CO2 beam, and vice versa. Two numbers on the frame matter:
- Wavelength range — must cover your machine. A blue diode is around 450 nm; an IR diode or fibre is around 1,064 nm; CO2 is 10,600 nm.
- OD (optical density) — how much it attenuates. OD 5 or above is the usual recommendation for Class 4 work.
Common questions
What class is a laser cutter?
The laser inside any machine that cuts is Class 4 — over 500 mW, hazardous to eyes and skin including from scattered light, and a fire risk. A fully enclosed machine with working interlocks can be sold as a Class 1 product, because the enclosure prevents access to that beam. Open-frame machines are Class 4 products.
Is a 5 W diode laser dangerous?
Yes. Five watts of optical power is ten times the upper limit of Class 3B, so it is firmly Class 4. It can cause permanent retinal damage from light scattered off the workpiece, burn skin, and start fires. Low wattage compared with a CO2 tube is not the same as low risk.
Do I need laser glasses with an enclosed machine?
If the enclosure is intact and the interlocks work, the product is Class 1 in normal use and glasses are not required for operation. Keep a rated pair anyway for alignment and maintenance, when the lid is open and the interlock is defeated — which is exactly when the beam is accessible.
Will any laser safety glasses work?
No — they are specific to a wavelength range. Glasses for a 450 nm diode give no protection against a 10,600 nm CO2 beam. Check that the frame states a wavelength range covering your machine and an optical density of OD 5 or higher, and distrust unmarked tinted goggles supplied with cheap machines.