What is DPI in Laser Engraving and How to Use It

If you’re diving into the world of laser engraving, you’ve likely come across the term DPI, or Dots Per Inch. At first glance, it might seem like just another technical setting buried in your laser software, but understanding DPI is key to achieving clean, detailed, and efficient results. Whether you’re engraving intricate designs into wood or creating frosted artwork on glass, your DPI setting can make the difference between a professional finish and a blurry mess.

In this article, we’ll break down what DPI really means in the context of laser engraving, how it interacts with different materials, and how to choose the right DPI for the job. Stick around for practical tips, material-specific advice, and a look at OMTech laser machines.

What Is DPI in Laser Engraving?

DPI stands for Dots Per Inch. While that term is widely used in printing and digital imaging, it has a slightly different—and often misunderstood—meaning in the context of laser engraving. In laser terms, DPI actually refers to how many horizontal lines your machine engraves in the space of one vertical inch. For this reason, many experts argue it would be more accurate to call it LPI or Lines Per Inch.

When your laser moves horizontally across a material, it burns or etches a line, then moves slightly vertically before starting the next horizontal pass. The higher the DPI, the closer together these passes are, resulting in greater detail, a longer engraving time, and more heat accumulation.

DPI Equals Vertical Resolution

Think of DPI as your vertical resolution. Just like increasing the resolution of a digital image gives you more clarity, increasing the DPI gives your laser engraver the ability to add more detail—especially in complex or photo-based designs. But there's a catch: too much DPI can be a bad thing, depending on the material you’re working with.

Let’s explore how DPI affects two common materials: wood and glass.

DPI and Wood Engraving: Less Is Often More

Laser engraving on wood works by burning or charring the surface. Wood is a porous, organic material, and as your laser heats it up, the burn can “bleed” slightly outside the intended line. This results in thicker engraved lines than what your machine technically outputs.

That’s why a higher DPI is often counterproductive on wood. When lines are too close together, they start to overlap, producing muddy or overly dark areas and increasing your engraving time significantly without improving quality.

Best Practice:

Use a moderate DPI, just enough to capture the detail you need. Running tests with different DPI values is the most reliable way to find the sweet spot.

DPI and Glass Engraving: Fine Control Is Critical

Glass behaves very differently. When struck by a laser, it doesn’t burn; instead, the heat creates tiny surface fractures due to rapid thermal expansion and cooling. These micro-cracks scatter light, giving glass engravings their frosted white appearance on a darker background.

The challenge with glass is that heat can travel more than you’d expect, potentially leading to larger-than-intended cracks and poor detail reproduction. Here, the role of DPI is crucial—but so are speed and power settings.

Best Practice:

Run a speed/power matrix test—also called a material test—before choosing your DPI. This helps you understand how your specific glass reacts under different conditions. Once you’ve dialed in those settings, experiment with DPI to find the lowest value that still gives you enough detail. This reduces engraving time and minimizes the risk of thermal damage.

What DPI Is Best for Laser Engraving?

There’s no one-size-fits-all answer, but the guiding principle is this: use the lowest DPI that still provides the level of detail your project requires. This ensures the fastest results with the least chance of overheating, especially on sensitive materials like glass or acrylic.

Here’s a quick guideline:

• 100–150 DPI: Good for wood, leather, and large graphics where detail isn’t critical.
  

• 200–300 DPI: Ideal for most standard projects, balancing speed and detail.
  

• 400–600 DPI: Best for photo engraving or extremely fine detail—mainly on materials that tolerate high heat (e.g., anodized aluminum).
  

• Above 600 DPI: Usually not necessary and can lead to overheating or loss of clarity due to overlapping lines.
  

Remember, at a .1 mm interval, your machine delivers 254 DPI. If you decrease that interval to .07 mm, you effectively increase the DPI and bring the lines closer together. This improves detail but increases job time and the risk of material distortion.

DPI, Speed, and Power: The Balancing Act

DPI doesn’t work in isolation. It must be considered alongside laser speed and power. A lower DPI combined with higher speed might give better results than a high DPI with too much power. That’s why running material tests before starting a new project is so important.

For example, you might find that on glass:

• At 200 DPI, 30% power, and 150 mm/s speed = clean frost.
  

• At 400 DPI, 40% power, and 100 mm/s = excessive cracking and haze.
  

Always test before committing to a full job.

A Note on Line Interval

In LightBurn, DPI settings are sometimes expressed as line intervals—the distance between each pass, measured in millimeters. Lower line intervals = higher DPI. Understanding this relationship is key to fine-tuning your engraving.

Final Thoughts: Experimentation Leads to Optimization

Laser engraving is part science, part art. The best way to understand how DPI affects your results is to engrave the same image at multiple DPI values, inspect the results closely, and pick the one that balances speed, clarity, and safety for your material.

Try OMTech: Precision Meets Versatility

Most OMTech laser machines are fully compatible with LightBurn, giving you total control over DPI, speed, power, and more. Whether you're engraving on wood, glass, acrylic, or metal, OMTech provides the power and flexibility to optimize every project detail.

Get started today with an OMTech laser engraver and unlock your creative potential with precision, reliability, and LightBurn compatibility.