LEDs per Metre vs Pixels per Metre on LED Strips

LEDs per metre and pixels per metre measure different things

LEDs per metre counts the LED packages along a strip. Pixels per metre counts the independently controlled lighting units along that strip. The two numbers are equal only when each LED package is independently controlled. A driver can instead control several packages together, so a strip with 60 LEDs per metre might have 20 pixels per metre in a grouped design.

This page concerns lighting strips. It does not use “pixel density” in the display-screen sense of pixels per inch, display resolution or screen pixel pitch. A strip specification needs a length unit and a clear definition of what is being counted.

Read a grouped strip without overcounting pixels

Imagine a uniform one-metre strip containing 60 LED packages, arranged in groups of three. Each group receives one independent RGB setting. This hypothetical design has:

• 60 LED packages per metre;
• 3 LED packages per control pixel;
• 20 independently controlled pixels per metre.

The arithmetic is 60 ÷ 3 = 20. It applies only if every group has the same structure and each group really is controlled independently. A product may use a different group size or count a complete fixture as its control unit. Adafruit's TM1814 explanation gives a concrete example of multiple RGBW packages sharing a driver; it does not establish the grouping of other models.

In the diagram, twelve LED symbols sit inside four control outlines. It shows the distinction between counts, without assigning a physical length. To turn those counts into densities, the measured segment length must also be known.

Calculate density from a known segment

Divide the number of units by the segment length in metres. A two-metre section containing 120 packages and 40 independent pixels has 60 LEDs/m and 20 pixels/m. Counting packages on a short photograph without knowing its scale cannot give either per-metre value.

For evenly spaced independent pixels, the nominal centre-to-centre spacing is 1,000 ÷ pixels/m in millimetres. At 20 pixels/m, this is 50 mm. A curved, clustered or uneven layout needs its actual drawing; an average density does not describe every gap or the spacing between separate fixtures.

What changes when pixel density increases?

More independent positions can represent smaller spatial changes in an effect along the strip. That can matter for a moving gradient, a chase or a mapped ceiling. It does not guarantee a smoother-looking installation: the diffuser, distance to the viewer, physical spacing between lines and the content itself also affect the result.

LED package density answers a different question about the distribution of light sources. It cannot by itself establish brightness, power consumption, color quality or visible dot-free diffusion. Those require the model's optical and electrical specifications, and a representative sample when appearance matters.

To connect the counts with actual buying decisions, the LED-strip specification guide covers the broader selection process. Keep the original units in the brief instead of reducing the choice to “higher density is better.”

Carry the pixel count into the controller budget

For a hypothetical 10-metre run at 20 pixels/m, there are 200 independent pixels. At three 8-bit color channels per RGB pixel, the color data occupies 600 channels. Those calculations do not establish a controller's usable output length, refresh performance or power capacity. Firmware, output limits, grouping and the chosen fixture mode must also fit.

Use the controller capacity calculator after confirming pixels/m and channels per pixel. Entering 60 LEDs/m as though it meant 60 pixels/m would triple the assumed pixel count in this example.

Keep cut length as a separate specification

A cut interval is the manufacturer-approved physical division of a particular strip. Pixel density does not grant permission to cut at every pixel boundary. The flexible PCB, pads, circuitry and enclosure determine the permitted cut positions.

Record LEDs/m, pixels/m, LED packages per pixel, approved cut interval in millimetres and requested finished length as separate fields. If a supplier lists only “60/m,” ask which unit is meant. That one clarification prevents a light-source count from silently becoming the control resolution or the cut length in the quotation.