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July 1, 2026 · 7 min read
PNG is a lossless format, which is exactly why its files get so big: it stores every pixel perfectly instead of throwing detail away. That's great for crisp logos and screenshots, but a single PNG can easily run to several megabytes — far too heavy for a web page or an email. The good news is that you can usually cut a PNG's size by 50–90% without any visible loss. Here are the four methods that actually work, from gentlest to most aggressive.
A PNG records the exact colour of every pixel, and a full-colour PNG (called PNG-24) can store over 16 million colours. For a photograph that's a huge amount of data — which is why a photo saved as PNG is typically five to ten times heavier than the same photo as JPEG. PNG only compresses well when an image has large areas of flat, repeated colour, like a logo or a diagram.
So the first question is always: what's actually in the image? The answer decides which method below will help most.
If your image is a logo, icon, illustration or screenshot with a limited palette, you rarely need 16 million colours. Converting from PNG-24 to PNG-8 reduces the image to a palette of up to 256 colours, which can shrink the file by 60–80% with no visible difference on flat-colour graphics.
This is the single biggest win for graphics. It only hurts on images with smooth gradients or photographic detail, where 256 colours aren't enough and you'd see banding — in that case, use method 3 or 4 instead.
File size grows with the number of pixels, so a 4000-pixel-wide PNG holds roughly four times the data of a 2000-pixel one. If the image is displayed much smaller than its actual resolution — which is almost always the case — resizing it to the size it's really shown at is free, instant savings.
Decide how wide the image actually appears (a little extra for high-resolution screens is fine), then resize to that width before doing anything else. On its own, resizing can cut file size by 75% or more.
Most PNGs exported from design tools, phones or screenshots contain redundant data and aren't optimally compressed. A good PNG compressor re-encodes the image and strips unnecessary metadata, typically saving 20–50% with zero quality loss — the pixels stay identical, the file just gets packed more efficiently.
Our compressor does exactly this in your browser: drop the PNG in, and it re-compresses it locally without uploading anything. Combine it with a colour reduction for the biggest effect.
PNG files get large for three distinct reasons, and the right fix depends on which one applies. The first is dimensions: a 3000-pixel-wide image contains nine times the data of a 1000-pixel one. The second is colour count: PNG-24 can store 16 million colours, and every one it tracks costs space. The third is the alpha channel, which adds a fourth value to every single pixel whether or not the image is actually transparent anywhere.
You can usually diagnose this by eye. If the image is a photograph, the problem is that PNG is the wrong format entirely. If it is a screenshot, it is almost certainly oversized. If it is a logo or icon exported from a design tool, it is probably carrying a 24-bit colour depth and an alpha channel it does not need.
Working out which of the three applies takes ten seconds and determines whether you save 20% or 90%.
Reducing dimensions is the most effective way to shrink a PNG and consistently the most overlooked. File size scales with pixel count, so halving both width and height cuts the file to roughly a quarter. Unlike quality reduction, it costs nothing visually as long as the image remains larger than the size it is displayed at.
The reference point is display size, not source size. For a high-density screen, export at about twice the width the image will actually occupy: 1600 pixels for a full-width banner, 800 for a half-width image, 400 for a thumbnail, 64 for an icon. Anything beyond that is downloaded and then discarded by the browser.
Screenshots taken on Retina and 4K displays are the standard offender here. They routinely arrive at double or triple their display size, which means a 1.2MB screenshot becomes a 300KB one with no perceptible change.
PNG has two colour modes and most tools default to the expensive one. PNG-24 stores full 16-million-colour depth, which a photograph needs. PNG-8 stores an indexed palette of up to 256 colours, which is more than enough for the overwhelming majority of logos, icons, diagrams and flat illustrations.
Converting a suitable image from PNG-24 to PNG-8 commonly cuts the file by 60–70% with no visible difference, because the image never contained more than a few dozen distinct colours to begin with. A two-colour logo stored as PNG-24 is paying for 16 million colours it does not use.
The limitation is dithering. If your graphic contains a smooth gradient, reducing it to 256 colours will produce visible banding or a speckled dithering pattern. Flat colours and sharp edges convert cleanly; gradients do not. Check the result before committing.
PNG files carry optional chunks alongside the image data: colour profiles, gamma information, text comments, creation timestamps, and whatever the exporting application decided to embed. Design tools are particularly generous here — a PNG exported from a design application can carry tens of kilobytes of metadata for a small icon.
On a large photographic PNG this is noise, worth a percent or two. On a 20KB icon it can be a third of the file. Stripping metadata is completely lossless as far as the visible image is concerned, so there is no reason not to do it for web assets.
The one thing worth keeping is the colour profile, if the image contains colours that must reproduce accurately — brand colours in a logo, for instance. Removing an embedded profile can shift colours subtly on wide-gamut displays.
There is a point past which PNG optimisation is a losing battle, and recognising it saves a lot of time. If the image is a photograph, no amount of palette reduction or metadata stripping will make PNG competitive — you are fighting the format's fundamental design. A photograph as PNG will be five to ten times larger than the same photograph as JPEG or WebP, and that gap does not close.
The modern answer is lossless WebP, which does everything PNG does — every pixel preserved, full alpha channel — while typically coming out 25% smaller. It is supported by every current browser, so for anything destined for a website there is essentially no reason to prefer PNG.
If the image is photographic and you need transparency, lossy WebP is the format that does both, and it will be an order of magnitude smaller than the PNG. Keep PNG for the cases where it genuinely wins: assets you are still editing, and files going somewhere that only accepts PNG.
The biggest reductions come from leaving PNG behind when it isn't the right tool. If your image is a photograph and doesn't need a transparent background, save it as JPEG or WebP instead — you'll often go from 4 MB to under 300 KB with no visible difference. If you do need transparency but want it lighter, lossless WebP keeps the transparent background while beating PNG on size.
A simple rule: keep PNG for flat-colour graphics and anything transparent; switch to JPEG or WebP for photos. Whatever you choose, drop the file into our compressor to squeeze out the last kilobytes — everything runs locally, so your image never leaves your device.