Power Level Requirements for Laser Therapy

Every day, the most common question we answer is about power levels. Every manufacturer has a unique marketing strategy about why they have the "right" amount of power, so this guide summarizes the entire market and draws some conclusions. The general trend is toward more power in cold lasers—but more isn't always better for every application.

Why Power Requirements Are Complicated

One of the complexities of laser therapy is the huge variation in treatment area size and treatment depth. As treatment depth increases, target energy at the surface must increase because most energy is absorbed on the way down. Larger treatment areas also increase dosage requirements. These factors have major effects on total therapy dosage—and as dosage increases, treatment time increases.

Depth

The biggest factor causing sub-optimal dosages is treatment depth. The most universally accepted standards were developed by the World Association for Laser Therapy (WALT), recommending 4–12 J/cm² at the target tissue—not at the surface.

Experience shows that to achieve this photon density at depth, the laser must deliver 5–10× that density at the surface. That's because 70–90% of energy is absorbed before reaching the target area.

What this means: Surface energy should be 24–100 J/cm² based on WALT standards for optimal results at 2+ inches of depth. Larger patients require more; smaller patients require less.

Area

Treatment area varies dramatically between conditions. Arthritis in one finger is a shallow, small area. Neuropathy from a pinched nerve in the lower back requires treating a large, deep area to ensure adequate energy density reaches the damaged tissue.

The difference between these two scenarios can mean treatment times ranging from seconds to hours depending on your laser's power output.

Treatment Time Comparisons

The following tables illustrate how power level affects treatment time for two very different conditions. Note: Target energies listed are at the surface—density at depth could be up to 90% less.

Example 1: Finger Arthritis

Depth: 1cm | Area: 6 cm² (approximately 1 square inch)

Surface Density	Total Dosage	100mW System	1,000mW System	10,000mW System
10 J/cm²	60 J	10 minutes	60 seconds	6 seconds
24 J/cm²	144 J	24 minutes	144 seconds	14 seconds
48 J/cm²	288 J	48 minutes	288 seconds	28 seconds

Insight: Any laser will treat this condition. A Class 4 laser is overkill here. A 100mW laser is the lowest-cost option and works fine—treatment time will be 10+ minutes but that's acceptable for a small area.

Example 2: Lower Back Neuropathy

Depth: 3cm | Area: 300 cm² (treating hips/lower back region)

Surface Density	Total Dosage	100mW System	1,000mW System	10,000mW System
4 J/cm²	1,200 J	3.3 hours	20 minutes	2 minutes
12 J/cm²	3,600 J	10 hours	60 minutes	6 minutes
24 J/cm²	7,200 J	20 hours	120 minutes	12 minutes

Insight: Even Class 4 lasers have meaningful treatment times at higher dosages. Very low-power lasers that worked perfectly for finger arthritis will never achieve adequate energy density at depth in a reasonable timeframe.

Power vs. Treatment Time Reference

This table shows treatment times across a wide range of power levels and target energies. Use it to understand what's realistic for your applications.

Power	50 J	500 J	1,500 J	5,000 J	15,000 J
5mW	2.7 hrs	1.1 days	3.4 days	11 days	33 days
100mW	8 min	83 min	4.2 hrs	13 hrs	39 hrs
500mW	1.6 min	16 min	50 min	2.7 hrs	8.1 hrs
1W	50 sec	8.3 min	25 min	83 min	4.1 hrs
5W	10 sec	1.6 min	5 min	16 min	50 min
10W	5 sec	50 sec	2.5 min	8 min	25 min
30W	2 sec	17 sec	50 sec	2.7 min	8 min
60W	<1 sec	8 sec	25 sec	83 sec	4 min

As you can see, some lasers are overpowered for some applications and underpowered for others. Most higher-power systems can be turned down when less is needed.

Two Types of Laser Therapy

Pinpoint Therapy

Uses a narrowly focused beam to treat trigger points or acupoints. Because the treatment area is extremely small, power levels can be very small too. If you're primarily doing trigger point or acupoint therapy, you don't need high power.

Broad Coverage Therapy

Treats large areas of damaged tissue—knees, hips, spines. Treating a large leg injury with a single focused beam would be like coloring a piece of paper with a ballpoint pen. It could take all day and the results wouldn't be good.

This is why many manufacturers gang together multiple laser beams or diverge the beam to cover larger areas evenly—and why power levels keep going up. For general tissue therapy, emitter outputs go up to 50,000mW (50W).

Wavelength & Power Interaction

Wavelength mainly controls penetration depth. There are two schools of thought about optimal wavelength:

600–660nm Range

This camp says you don't need deep penetration to address the root cause, and you don't need huge power since most energy is absorbed near the surface. Companies like Erchonia have gotten good results with as little as 20mW in this range, emphasizing pulsing frequency over power.

800–980nm Range

This camp says higher wavelengths provide much deeper penetration—then they disagree about how much power you really need. Products for this range vary from 40mW to 50,000mW. This is where the real controversy exists, especially for large-area, deep-tissue conditions like knee injuries.

Both groups consistently get good results. We typically advise getting a device with both ranges if budget allows.

Continuous vs. Pulsed Power

Most quality lasers offer both Continuous Wave (CW) and Pulsed Wave (PW). Understanding when to use each mode helps optimize results.

Continuous Wave (CW)

The laser beam is on 100% of the time. Best for maximum pain relief—allows you to reach the plateau faster and saturate the area. Also delivers energy faster when treatment time is critical.

Pulsed Wave (PW)

The beam turns on and off at a fixed rate (typically 1,000–5,000 times per second). Pulsing offers additional benefit in stimulating the body that more than offsets the reduced delivery speed. For higher-power systems, pulsing also allows higher power levels without burning risk—both the emitter and tissue cool during off periods.

Sweeping Mode

The pulsing frequency changes over the treatment period. If you don't know the optimal pulsing frequency for a condition, sweeping will hit the optimum at least some of the time.

Note on Pulsing: The general consensus is that pulsing provides additional benefit beyond total energy dosage. Many people get great results with lower-power pulsing systems. However, we can't yet quantify the benefits of pulsing in numbers, so it's difficult to include in dosage calculations. Pulsing also keeps lasers cooler, reducing system cost—making lower-power pulsing and super-pulsing lasers a great option even at lower target dosages.

Why Laser Power Keeps Increasing

Power levels in new products are rapidly growing for several reasons:

Improved diode technology: 20 years ago, a 50mW laser diode had a relatively short life. Now, 500mW or even 50,000mW modules commonly last 10+ years.
Broader treatment coverage: Manufacturers gang multiple beams or diverge beams to cover larger areas evenly, requiring more total power.
Deeper tissue targeting: As practitioners target deeper conditions, more surface power is needed to deliver adequate energy at depth.
Shorter treatment times: Higher power means faster treatments, which matters for busy clinical practices.

Since power level is a controlled variable in FDA clearance, updating older products to new technology can be expensive—which is why some super-low-power devices remain on the market. Also, there's significant cost difference between low and high-power diodes, so some manufacturers use very low-power components to keep prices down.

Finding Optimum Power

All major brands produce beneficial cellular stimulation, but the question is what dosage provides the best results. Based on WALT research, here's what we understand:

Pain Relief

Higher dosages provide increasingly better pain relief—but there must be a maximum where adding more energy is just wasting time. We don't know exactly where this point is, and dosage recommendations vary widely between manufacturers.

Cellular Stimulation

Initially, more energy means more cellular stimulation. But there's an inflection point where adding more energy actually reduces stimulation and starts inhibiting cellular activity. This is the biphasic dose response.

Long-Term Results

Many smaller doses are probably best for long-term cellular regeneration—but most patients won't stick with therapy that isn't producing noticeable results. This is why most practitioners prefer delivering higher dosages than WALT typically recommends.

There's no single right answer. This is why people get great results with both Class 1 and Class 4 lasers. The operator must evaluate every patient and decide how fast they want to progress through therapy.

Why Doesn't Everyone Buy Class 4?

If more power reduces treatment times and enables optimal dosages, why doesn't everyone buy the highest-power lasers? Two reasons: cost and safety responsibility.

Cost

Lasers are expensive, and no one wants to buy more than they need. That's why we work with customers to match each laser to specific needs. A Class 4 system is overkill for someone primarily treating small, shallow conditions.

Safety Responsibility

Class 4 products are by definition the most potentially dangerous on the market. If used improperly, they can cause permanent eye damage and, in some cases, minor burns. With proper training and discipline, these products are completely safe and provide the most consistent results across the widest range of applications. If misused, they can create serious problems.

With great power comes great responsibility. If the individual using a Class 4 laser is properly trained and disciplined, it's a great investment. If misused, it's a liability.

Watch Out For: Treatment Time Marketing

When comparing lasers, be aware that different manufacturers have different specifications for optimum power density. Since treatment time is a big selling point, manufacturers of lower-power devices may target much lower power densities than industry standards—because no one will buy their product if they admit you'd need to leave the laser on one spot for 40 minutes.

Products that never achieve optimum power levels can still help patients with minor issues, but they might not help with larger, deeper problems. Always ask: what dosage is this protocol actually delivering at depth?

Key Takeaways

1

Shallow, small areas can easily be treated with lower wavelengths and lower power lasers. Large damaged areas are best treated with higher power in the IR range.

2

Deeper injuries require more power to achieve optimum photon density in a reasonable amount of time. 70–90% of energy is absorbed before reaching deep targets.

3

Power level mainly affects treatment time. In some cases, low-power lasers will never achieve optimum energy in a reasonable timeframe.

4

Laser technology has evolved. Affordable, reliable high-power lasers are now possible that weren't available before.

5

You get what you pay for. More expensive machines offer more flexibility, helping practitioners get more consistent results across a wider range of patients.

6

Class 4 lasers require proper training but allow treatment of larger and deeper areas in reasonable timeframes.