Does a higher PNG compression level make a smaller file?

Choosing a PNG compression level? More effort can shrink the file without changing the picture, though a higher setting doesn't always make it smaller.

FluffyBench · 6 min read · Reviewed October 15, 2026

What does a PNG compression level change?

Think of packing a suitcase: spending longer folding the clothes can leave more room without taking anything out. PNG compression works the same way: Fast spends less effort looking for ways to pack the picture's data; Maximum spends more, with Balanced in between.

Two suitcases contain the same four colored shirts, loosely spaced on the left and neatly packed on the right. — A compression level changes packing effort, not picture quality. How we reviewed

Color mode and resizing can change the picture. Leave those choices alone when you compare compression levels.

Does a higher PNG compression level make a smaller file?

It can. Maximum made the smallest PNG for both images here. The photo came out about 2.4% smaller than at Fast; on the flat graphic, Balanced was about 0.8% larger than Fast. A higher level asks for more searching, not a particular file size.

Here's a Dream Lake photograph that started as a JPG, with the same patch before and after saving at Maximum. The three sizes belong to complete PNG copies of that photo.

Matching forest and rock crops from the source JPG and Maximum PNG, above exact PNG file sizes for Fast, Balanced and Maximum. — Maximum saves a little space without changing the pictured detail. · Photo: John Marino / NPS Photo, National Park Service, Public domain in the United States: National Park Service employee work produced in official duties, via Wikimedia Commons.

This flat interface graphic was already a PNG. Its middle setting produced the largest copy, so you can't assume each step up will save space.

Matching interface panel crops from the source PNG and Maximum PNG, above exact file sizes for Fast, Balanced and Maximum. — For the graphic, Maximum is smallest and Balanced is largest.

Wondering why a PNG made from a JPG can be much larger? Why image files get larger explains that separate format choice.

How much longer does PNG compression take?

Maximum took longest in all four image-and-browser pairs. The extra wait bought a modest saving on the photo, and the waiting time varied with both the image and browser.

Photo - Chrome

Common time scale: 1,345 ms

Fast: 854 ms
Balanced: 862 ms
Maximum: 1,050 ms

Photo - Firefox

Common time scale: 1,345 ms

Fast: 904 ms
Balanced: 1,126 ms
Maximum: 1,345 ms

Graphic - Chrome

Common time scale: 1,345 ms

Fast: 461 ms
Balanced: 457 ms
Maximum: 466 ms

Graphic - Firefox

Common time scale: 1,345 ms

Fast: 487 ms
Balanced: 500 ms
Maximum: 718 ms

Median time from clicking Convert to completion, including the page's work; shorter bars mean less waiting.

There isn't one best tradeoff for every job. If you're making a single copy, a little extra waiting may be fine. If you're processing a folder, a small saving on each image may matter less than finishing sooner.

Doing it in FluffyBench: choosing a PNG compression level

FluffyBench's PNG converter lets you compare the levels on your own picture. Keep your original; the walkthrough makes separate PNG copies, starting with Fast.

Make the Fast copy first. The color, sample depth, interlace and Size choices stay unchanged for the comparison.

Step 1. Choose your image and leave To on PNG. Open Settings.
1. Choose images opens your file picker.
2. To is already PNG.
3. Open Settings for the PNG controls.
Step 2. Open More options and choose Advanced local encoder. Choose Fast; leave RGBA, 8-bit and interlace off as shown.
1. More options reveals the PNG choices.
2. Advanced local encoder makes compression levels available.
3. Use Fast first. RGBA keeps color and alpha; 8-bit sets sample depth; interlace changes loading order.
Step 3. Keep Size on Original so both copies have the same dimensions.
1. Original keeps the pixel dimensions.
Step 4. Close Settings with the gear button.
1. Press the gear again to close Settings.
Step 5. Press Convert 1 to PNG to make the Fast copy.
1. Convert 1 to PNG creates the copy at Fast.

Now compare Maximum on the same image. Keep the copy whose size is worth the wait for your job.

Step 1. Read the Fast output size and Download this copy. Reopen Settings for the comparison.
1. Read the output size on the second size line.
2. Download saves the Fast PNG to your device.
3. Open Settings to change the compression level.
Step 2. Change PNG compression to Maximum. Leave the other choices as they were.
1. Choose Maximum for the second copy.
Step 3. Close Settings with the gear button.
1. Press the gear again to return to the image.
Step 4. Press Reconvert 1 to PNG to replace the displayed result with the Maximum copy.
1. Reconvert 1 to PNG makes the second copy at Maximum.
Step 5. Compare the Maximum PNG size with the Fast copy you saved.
1. Read the output size on the second size line.

For the other controls, which PNG settings are worth changing explains when color mode, sample depth and interlace help. For a smaller photo copy where exact pixels don't matter, FluffyBench's JPG converter gives you a quality setting to trade some picture detail for space.

Compare compression levels on your own image with FluffyBench's PNG converter.

FluffyBench's PNG converter

How we reviewed PNG compression levels

These are the complete median waiting times behind the timing chart.

Setting	Photo · Chrome	Photo · Firefox	Mock · Chrome	Mock · Firefox
Fast (level 1)	854 ms	904 ms	461 ms	487 ms
Balanced (level 6)	862 ms	1,126 ms	457 ms	500 ms
Maximum (level 9)	1,050 ms	1,345 ms	466 ms	718 ms

Read down a column to compare levels for one image and browser.

How we reviewed

Reviewed October 15, 2026

We ran each input, setting and browser combination three times in a fresh page, with no warm-up, on 15 October 2026. The inputs were dream-lake-nps.jpg (reference photograph; 990.8 KB; 1920 × 1275 pixels) and png-levels-ui-sample.png (first-party generated flat interface sample; 14.1 KB; 1200 × 800 pixels). The runs used Chromium 153.0.8010.12 and Firefox 155.0 on Windows 11, shared desktop machine in a local build.

The results cover two single-file inputs. The sample is generated artwork, not a captured application screenshot. Action times run from clicking Convert to the page reporting completion, including interface and polling overhead.

Only the compression level changed: Advanced local encoder, RGBA output at eight bits per channel, interlace off; Fast = 1, Balanced = 6, Maximum = 9. Output bytes are exact counts; displayed sizes use decimal KB and MB. The matched source and Maximum crops were recreated with the app encoder and checked against the recorded output sizes. Crops are 450 x 338 pixels for the photo and 400 x 300 for the graphic, scaled equally within each pair. The packing diagram is conceptual.

Each action-time median comes from three runs on a shared machine. The three Chrome runs at Maximum on the photo took between 1,046 ms and 1,065 ms.

The run did not compare browser-default PNG output and covered no palette, grayscale, RGB, 16-bit, or Adam7 mode. It did not separate encode time from interface time, run on a phone, or measure process memory or visual preference.

Image credits

Hallett Peak reflected in Dream Lake — John Marino / NPS Photo, National Park Service. Public domain in the United States: National Park Service employee work produced in official duties. An enlarged crop from the 1920-pixel Commons thumbnail sits beside remeasured PNG output bytes; the interface sample beside it is first-party artwork.