How to Read a Therapy Laser Spec Sheet
A therapy laser spec sheet is where the marketing gets slippery. The same device can look twice as powerful as its neighbor just by writing the numbers a different way. Here is how to read the specs honestly, so you compare lasers on what actually reaches the tissue instead of what looks biggest on the page.
The class on the box is a safety rating, not a quality score
Laser classes (Class 3R, Class 3B, Class 4) come from an international safety standard. They describe how hazardous the beam is to eyes and skin, and they are set purely by power output:
| Class | Output power | What it tells you |
|---|---|---|
| Class 3R | Up to 5 mW | Very low power |
| Class 3B | 5 mW up to 500 mW (half a watt) | Low power, often called "cold laser" or LLLT |
| Class 4 | Above 500 mW (over half a watt) | Higher power |
That is the whole definition. "Class 4" literally means "more than half a watt," and nothing more. A 1.5 watt laser and a 30 watt laser are both Class 4, even though they are worlds apart. So the class number is a useful starting point, but it is not a measure of quality, effectiveness, or how much power you are actually buying. Read past it to the real numbers.
Watts: average power is real, peak power is the trick
The single most common way a spec sheet inflates a laser is by advertising peak power instead of average power.
Average power is the steady, sustained output the laser actually delivers over time. It is the number that determines how quickly you can deliver a treatment dose. Peak power is the instantaneous maximum the laser hits for a tiny fraction of a second, most relevant to pulsed and "superpulsed" lasers that fire in very short bursts.
The gap between the two can be enormous. A superpulsed laser can advertise a peak figure in the tens of watts while its average power is a small fraction of one watt. Both numbers are technically true, but only the average power reflects the energy the tissue receives over a full treatment. When a spec sheet leads with a big wattage, the honest question is simply: is that average power, or peak?
"Multi-wavelength" watts are usually added together
Many higher-power lasers use several laser diodes at different wavelengths. A common way to write the spec is to add every diode together and print the total as the headline wattage. A laser described as "40 watts" may really be four separate diodes of about 10 watts each, at four different wavelengths. No single wavelength is putting out 40 watts, and the deep-penetrating wavelength that does most of the work may be only a quarter of the total.
This is not necessarily wrong, and multi-wavelength lasers are genuinely useful. But it means the headline number is a sum, not the output at any one wavelength. To compare two multi-wavelength lasers fairly, look at the average power at each wavelength, not just the combined figure on the front page.
Wavelength matters as much as wattage
Wattage is how fast you deliver energy. Wavelength is where that energy goes. Different wavelengths are absorbed by different tissues and reach different depths:
| Wavelength range | General behavior |
|---|---|
| Red, roughly 600 to 660 nm | Absorbed near the surface. Good for skin, superficial tissue, and wounds. |
| Near-infrared, roughly 800 to 830 nm | Penetrates deeper. A workhorse range for deeper muscle and joint work. |
| Near-infrared, roughly 900 to 980 nm | Absorbed more by water, which can add a gentle warming effect. |
| Around 1064 nm | Reaches the deepest, useful for the heaviest tissue. |
A laser with more wavelengths can be matched to more conditions and tissue depths. In practice, the right blend of wavelengths often matters more than a bigger single number, which is why comparing lasers on watts alone can point you in the wrong direction.
What actually heals is dose, not watts
The therapeutic effect comes from delivering a target amount of energy to the tissue. Energy is measured in joules, and it is simply power multiplied by time. A laser rated in watts is delivering a certain number of joules per second, and clinicians aim for a dose measured in joules per square centimeter at the treatment area.
The practical consequence is this: two lasers can deliver the same healing dose. A higher average power just delivers that dose faster, which is why busy clinics value it. But watts are the means, not the outcome. A spec sheet that shouts about wattage and says nothing about dose, treatment time, or power density is telling you how loud the engine is without telling you where the car goes.
Continuous versus pulsed
A laser can run in continuous wave mode, where the beam is steady, or in pulsed mode, where it switches on and off rapidly. Pulsing can reduce heat buildup and some practitioners prefer it for certain protocols. "Superpulsed" lasers take this to an extreme with very short, very high-peak pulses and a low average power, which is exactly the case where the peak-versus-average distinction matters most. Neither mode is automatically better. What matters is the average power delivered and the dose achieved.
The honest questions to ask any laser seller
If a seller answers these clearly, you can trust their spec sheet. If they dodge, that tells you something too.
- Is that wattage average power or peak power?
- Is it the total across all diodes, or the output at a single wavelength?
- What are the wavelengths, and what is the average power at each?
- What is the recommended dose in joules per square centimeter, and the treatment time per area?
- Is it FDA-cleared, and for what?
- What is the warranty specifically on the laser diodes, not just the housing?
- What is the price? If they will not tell you without a sales call, ask why.
How we list our specs
We publish average power, the wavelengths and what each one is for, and real pricing, because that is the only way you can actually compare one laser to another. If a number on our site could be read two ways, we would rather explain it than let it look bigger than it is. If you want help translating a competitor's spec sheet into what it really means, call us and we will walk through it with you. No pressure, and we will happily tell you when a lower-power or lower-cost laser is the better fit for what you treat.
Frequently asked questions
Does a higher wattage laser heal better?
Not by itself. Healing depends on delivering the right dose of energy at the right wavelength to the right depth. Higher average power delivers that dose faster and helps with large or deep areas, but a lower-power laser can reach the same dose with more time. Watts are a measure of speed and depth, not of results.
What is the difference between peak power and average power?
Average power is the steady output the laser sustains, and it determines how quickly you deliver a treatment. Peak power is the brief instantaneous maximum, most relevant to pulsed and superpulsed lasers. A laser can have a very high peak and a very low average, so average power is the honest number for comparing everyday performance.
Why do two "40 watt" lasers perform so differently?
Often because one is a single high-power source and the other adds several smaller diodes together to reach the headline number. The wavelengths, the average power at each wavelength, and whether the figure is peak or average all change what actually reaches the tissue. Compare the details, not just the front-page watts.
Is Class 4 always better than Class 3B?
No. Class is only a safety rating based on power. Class 4 reaches deeper and treats faster, which suits large or deep targets and busy clinics. Class 3B is gentler and well suited to smaller, superficial, or sensitive areas and home use. The best class depends on what you treat. See our Class 3B vs Class 4 guide.
Why do some companies hide their prices?
Usually so pricing can be set per buyer in a sales call rather than compared openly. There is nothing illegal about it, but it makes honest comparison shopping harder. We publish prices so you can compare on the numbers.
Therapy lasers are FDA-cleared for the temporary relief of pain and inflammation and for increasing local blood circulation. They are not a substitute for clinical diagnosis or a treatment plan. Questions? Call (303) 666-1100 or email nick@therapylasers.com.