How to reduce image file size
The three levers, which one to reach for first, and how far each can go before the picture starts to suffer.
In short
Resize first if the image is larger than it needs to be — that is usually the biggest saving. Then convert to WebP. Then lower the quality. Doing all three in that order beats pushing any one of them hard.
A photo straight off a phone is often 4000 pixels wide and several megabytes. Displayed at 800 pixels on a web page, most of that is data nobody will ever see.
In order of what to try first
- 01
Resize to the size it will actually be displayed at
This is usually the largest saving and the one that costs the least, because you are removing pixels that were never going to be shown. Use Resize Image.
- 02
Convert to WebP
At the same visual quality WebP produces meaningfully smaller files than JPEG, and unlike JPEG it keeps transparency. Every current browser displays it.
- 03
Lower the quality
72% is the default and sits in the useful range. 60% is fine for most photographs. Below 50% the artefacts become obvious.
What to resize to
| Use | Width | Note |
|---|---|---|
| Full-width web hero | 1920 px | Beyond this is wasted on almost every screen |
| Article or blog image | 1200 px | Comfortable on a high-density display |
| Thumbnail or card | 600 px | Anything more is invisible |
| Email attachment | 1200 px | Legible without being heavy |
| Avatar | 400 px | Displayed far smaller than people expect |
The PNG special case
If your source is a PNG, the quality slider does nothing at all — PNG is lossless and has no quality parameter. The only way to make it meaningfully smaller is to convert it, which is why Compress Image switches WebP on automatically for PNG sources. If you need to keep PNG, resizing is your only lever.
Mistakes worth avoiding
- Compressing hard when the real problem is a 4000-pixel-wide image being shown at 800.
- Re-compressing an already-compressed JPEG. Very little left to remove, and it degrades further.
- Converting to WebP before checking the destination accepts it — some upload forms and older desktop software still do not.
Tools used in this guide
Related guides
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