Which PNG settings should you change?

Want a smaller PNG that looks exactly the same? In FluffyBench, changing how the picture is packed can save more space than turning compression up.

FluffyBench · 7 min read · Measured October 19, 2026 on 4 test images

What does a PNG setting change?

A PNG stores a picture as colored pixels. Think of a completed jigsaw: you can pack the same pieces into a smaller box, or replace them with a simpler picture. PNG compression does the packing; color choices can change the pieces. Start by changing how it’s packed before you simplify its colors.

Repacking keeps the colors you already have. A shorter palette gives the picture fewer shades to choose from.

Conceptual illustration: the top pair keeps every color; the bottom pair simplifies the shades. How we reviewed

Here, ‘unchanged’ means the saved picture comes back with the same pixels.

Start with FluffyBench’s advanced PNG encoder

In FluffyBench’s PNG converter, the PNG choices live in Settings, under More options. Advanced local encoder makes the color, depth, compression and interlace controls available.

More options panel with PNG encoding, color, sample depth, compression and interlace controls. — The settings below explain when each choice helps; the complete walkthrough follows them.

Advanced local encoder made every picture we tried 10.3% to 58.3% smaller than Browser default, with unchanged pixels. We used a mountain photo, flat app-screen art, a transparent Earth graphic and a PNG saved with 16-bit color.

Same pixels in every bar: Advanced starts at RGBA, 8-bit, Balanced, interlace off. RGB saves a little more on the three pictures without transparency; each group has its own scale.

Which color choice fits your picture?

RGBA keeps red, green, blue and transparency. Indexed palette stores a short color list, and each pixel points to a color on that list. That can be a great fit for flat artwork whose colors already fit the list.

A flat app-screen graphic, like artwork you’d export for an interface, came back unchanged with Indexed palette in a smaller file than RGBA. The edges and colors still match the source.

Matched detail from the same interface graphic; sizes describe the complete files.

A mountain photo has more shades than the short palette can keep unchanged: Indexed approximates them, while Grayscale removes the color. RGBA keeps the source picture’s pixels.

The enlarged sky detail makes the palette’s color steps easier to see; sizes describe the complete files. · Photo: John Marino / NPS Photo, National Park Service, Public domain, via Wikimedia Commons.

The mountain source is already a JPG; why image files get larger explains why its PNG copy grows.

On a see-through Earth graphic, RGB (no alpha) and Grayscale (no alpha) fill transparent areas with white; Grayscale also removes color. Keep RGBA when see-through areas matter.

The framed panels share a checkerboard and dark backing; white fill covers that backing in both no-alpha outputs. · Photo: NASA, Public domain, NASA-created image, via Wikimedia Commons.

For pictures without transparency, RGB is the small extra saving in the encoder chart above. It doesn’t reduce the color palette.

Does stronger compression save much?

Compression repacks the picture without changing its pixels. Maximum made these files 2.3% to 7.5% smaller than Fast—a modest saving beside the color choices.

Bytes saved by Maximum compared with Fast

Photograph: 2.4 %
Flat interface graphic: 7.5 %
Picture with transparent areas: 2.3 %
16-bit PNG: 5.1 %

Same pixels at RGBA, 8-bit, interlace off; Balanced isn’t always smaller than Fast.

For the separate question of waiting time, see PNG compression: file size and timing.

Do bit depth and interlacing help?

Leave PNG sample depth at 8-bit for ordinary PNG input in FluffyBench. Even a PNG saved with 16-bit color is decoded to 8-bit first, so 16-bit output can't restore the finer color steps lost on input.

Simplified precision path. The 16-bit PNG grew from 6.6 KB at 8-bit output to 7.8 KB at 16-bit output, without adding finer color steps.

PNG interlace arranges the picture in rough-to-complete passes. Leave it off unless you need that kind of preview while a picture is arriving.

Conceptual loading sequence, not a timed capture; interlacing changes the loading order, not the finished picture. · Photo: John Marino / NPS Photo, National Park Service, Public domain, via Wikimedia Commons.

Doing it in FluffyBench

This walkthrough uses flat art and Indexed palette; choose RGBA instead when you need the picture’s colors and transparency kept.

Step 1. Choose images, leave To on PNG, then open Settings.
1. Choose images opens your device’s file picker.
2. PNG is already selected as the output.
3. Open Settings to reach the PNG choices.
Step 2. Open More options and choose Advanced local encoder. Use Indexed palette for this flat graphic and leave the other PNG choices as shown.
1. More options reveals the PNG settings.
2. Choose Advanced local encoder for these controls.
3. Choose Indexed palette; leave 8-bit, Balanced and interlace off.
Step 3. Keep Size on Original to compare settings at the same dimensions.
1. Original keeps the picture’s pixel dimensions.
Step 4. Use the gear button again to close Settings.
1. Press the gear button again to close Settings.

With the settings chosen, you're ready to convert and save your PNG.

Step 1. Press Convert 1 to PNG to create the copy.
1. Convert makes a PNG with your chosen settings.
Step 2. Compare the output size and dimensions with the input. Use the picture comparisons above to decide whether the color choice fits.
1. The input’s dimensions and file size.
2. The new PNG’s dimensions and file size.
Step 3. Download saves the completed PNG to your device.
1. Download saves the completed PNG to your device.

Need fewer pixels as well as fewer bytes? Resizing, compression and conversion explains which job to choose.

Try these choices on your own picture with FluffyBench’s PNG converter.

FluffyBench’s PNG converter

How we reviewed PNG settings

We compared 4 inputs at their original dimensions. These counts show pixels changed by each color choice at 8-bit and Balanced compression, with interlace off.

Color type	Photograph	Flat interface graphic	Picture with transparent areas	16-bit PNG	Identical to the source
RGBA	0 of 2,448,000	0 of 960,000	0 of 311,920	0 of 6,144	48 of 48 outputs identical
RGB	0 of 2,448,000	0 of 960,000	97,176 of 311,920	0 of 6,144	36 of 48 outputs identical
Grayscale	2,420,875 of 2,448,000	631,476 of 960,000	310,499 of 311,920	6,137 of 6,144	0 of 48 outputs identical
Indexed	2,446,615 of 2,448,000	0 of 960,000	231,211 of 311,920	6,099 of 6,144	6 of 24 outputs identical

The last column counts identical pictures across every tested setting for that color type.

RGBA stayed unchanged in all 48 outputs. Indexed did so in 6 of 24, all for the flat interface graphic. Grayscale changed every sample. The 6 16-bit Indexed combinations were skipped because that choice isn't offered.

How we measured

Date: October 19, 2026. Browser: Chromium 153.0.8010.12 (bundled with the test tool). Device: AMD Ryzen 9 5950X, 32 logical processors, 137.3 GB memory, Windows 11 Pro.

Chrome's built-in PNG writer and the advanced local encoder at all 42 color-type, depth, compression and interlacing combinations allowed by Settings. Each input and setting was converted once at the input's original dimensions. The advanced encoder ran in Node from the same encoder code the converter uses; the browser baseline and all decoding ran in a blank Chromium page with network requests blocked.

4 test images. Photograph: 1,920 × 1,275 pixels, 990,763 bytes; Flat interface graphic: 1,200 × 800 pixels, 14,071 bytes; Picture with transparent areas: 560 × 557 pixels, 609,807 bytes; 16-bit PNG: 96 × 64 pixels, 32,097 bytes.

Sizes are exact byte counts, and KB and MB are decimal. Percentages are changes in output bytes from one setting to another, to one decimal. A pixel counts as changed if any channel differs after both files are decoded to 8-bit sRGB color with transparency.

Identical means identical after that decoding. It does not show that native 16-bit precision, color profiles, metadata or the hidden color beneath fully transparent pixels were kept.

The test recorded sizes only: no times, speeds or memory use, so it ranks no setting for speed. Firefox and phones were not measured, and neither was resizing.

Fast, Balanced and Maximum are compression levels 1, 6 and 9 in that order. Indexed has no 16-bit setting, so it has 24 outputs against 48 for each other color type.

The descriptions of PNG color types, bit depth and interlacing follow the W3C PNG Specification.