What Pixel Block Size Should You Use?
Block size is the only setting that really matters in a pixelation tool, and the right value depends on your image resolution more than on the look you want.
Last updated July 2026
Block size is the width in pixels of each square the effect averages together. A setting of 8 means the image is divided into 8 by 8 squares and each one is flattened to a single color. Larger blocks mean fewer, chunkier squares and more detail destroyed.
Quick reference
| Block size | Best for | What it looks like |
|---|---|---|
| 2 – 4 px | Subtle texture | Barely reads as pixelation. Adds a faint digital grain while leaving the subject fully recognizable. No privacy value. |
| 5 – 10 px | Retro / 8-bit art | The classic pixel-art look on a medium-sized photo. Shapes and colors survive, fine detail does not. This is why the tool defaults to 8. |
| 10 – 20 px | Heavy stylization | Strongly abstract. A face becomes a suggestion rather than a likeness, though build and hair color still read clearly. |
| 20 – 40 px | Censoring a face | The working range for anonymity on a typical photo. Features are gone. Verify by zooming out rather than trusting the number. |
| 40 – 100 px | Maximum obscuration | The region collapses to a few flat squares. Use when the area is large or when you want no doubt about the result. |
Scale the setting to your image
A block size of 8 on a 4000 pixel wide photo produces 500 blocks across the frame, which at normal viewing size is nearly invisible. The same 8 on a 400 pixel wide image produces 50 blocks across and looks dramatically chunky. The setting did not change; the resolution did.
Rather than memorizing values, think in terms of how many blocks you want across the thing you are pixelating:
- For an art effect, aim for roughly 60 to 150 blocks across the full image width. Divide your image width by that to get the setting. A 1600px image divided by 100 gives a block size around 16.
- For censoring a face, aim for 5 to 8 blocks across the face itself, not the image. If the face spans 240 pixels, that is a block size around 30 to 48.
The second rule is the one that keeps people safe, because it automatically compensates for a small face in a large photo, which is the situation where a fixed setting most often fails.
Getting a clean 8-bit look
For retro art, one detail improves the result noticeably: pick a block size that divides evenly into your image width. If the width is not an exact multiple of the block size, the final column of blocks is clipped, producing a visibly narrower strip along one edge.
A 1600 pixel wide image divides cleanly by 8, 10, 16, 20, 25, 32, 40 and 50. Choosing from that list rather than an arbitrary 23 gives you a uniform grid.
Export format matters here
Pixelated images are large areas of flat color with hard edges, which is the worst case for JPEG. Its compression introduces soft halos and color noise exactly at block boundaries, muddying the crisp edges that make the effect look good.
Use PNG for pixel art, logos, and anything with sharp block edges. It is lossless and compresses flat color regions efficiently, so files are often smaller than the JPEG equivalent. WebP is a reasonable middle ground for the web. Reserve JPEG for cases where the pixelated area is a small part of an otherwise photographic image.
Checking your work
For privacy work, the number is never the answer on its own. Two checks take a few seconds:
- Zoom out. View the image small, the way it will appear in a feed or thumbnail. Identity often survives at small sizes even when it looks destroyed at full zoom, because the eye reconstructs shapes from coarse color patterns.
- Ask someone who knows the subject. If a person familiar with them can still pick them out, the redaction has failed for the audience that matters most.
If either check fails, raise the block size. There is no downside to going further than necessary when the goal is anonymity, and our guide on reversing pixelation explains why the margin is worth having.
You can test any of these values directly in the pixelate image tool. The slider updates in real time, so it is quicker to drag until it looks right than to calculate the number first.
Try it yourself
Our pixelation tool runs entirely in your browser. Nothing is uploaded, nothing is stored, and there is no signup.
Open the pixelate tool