Image Resizer vs Image Compressor
Choose this if
the image is larger than it will ever be displayed, which is true of almost every photo straight from a camera or phone
Choose this if
the dimensions are already right and the file is still too big for its purpose
How they compare
| Criterion | Image Resizer | Image Compressor |
|---|---|---|
| What actually changes | The number of pixels. A 4000 × 3000 image becomes 1000 × 750 | How precisely those pixels are stored. The dimensions are untouched |
| Typical file saving | Halving both dimensions quarters the pixel count and usually cuts the file to roughly a quarterBetter here | Dropping quality from 90 to 75 typically saves 40 to 60%, with diminishing returns below that |
| Visible cost | None at the new size. The image simply cannot be displayed larger than you made itBetter here | Block edges and colour smearing, worst on flat areas, gradients and text |
| Reversibility | Not reversible: enlarging back interpolates and does not recover detail | Not reversible either, and repeating it compounds the damage through generation loss |
| Effect on a web page | Also reduces decode time and memory, because the browser holds fewer pixelsBetter here | Reduces transfer size only. The browser still decodes the full pixel count |
Which is best for you
Resize if the image is bigger than the space it goes in
A phone photo is around 4000 pixels wide. A blog header is 1200, a thumbnail is 300, and an email signature is 150. Serving 4000 to fill 300 wastes the bytes and makes the browser decode sixteen times more pixels than it draws. Resizing to the largest size the image will actually be displayed at is the single biggest win available, and it costs nothing visually.
Compress if the dimensions are already correct
Once an image is the right size, compression is what is left. It is the right tool for a hero image that must be 1600 pixels wide and still needs to come under 200 KB, or a PNG screenshot heading for a page-weight budget. Start at quality 75 and move up only if you can see the difference at the size it will be viewed.
The recommendation
Resize first, then compress, in that order, and usually you will find the second step is barely needed. Resizing removes pixels that were never going to be displayed, which costs nothing you can see, while compression always trades visible quality for bytes. An image cut from 4000 to 1200 pixels wide and saved at quality 80 will beat the same image left at 4000 pixels and crushed to quality 40, and it will look considerably better.
Frequently asked questions
Which one should I do first?
Resize, then compress. Compressing first and resizing afterwards means the compression artefacts get scaled along with everything else, and you pay for detail that is then thrown away. Resizing first also means the compressor has fewer pixels to work on, so the same quality setting produces a smaller file.
Why did compressing barely shrink my file?
Because it was probably already compressed. A JPEG from the web has been through an encoder once, and re-encoding it at a similar quality preserves the first pass's artefacts rather than removing detail. Resizing will still help, because the pixel count is independent of how the file was encoded.
Can I do both in one step?
Yes. The compressor has a width cap, which resizes before encoding. That is the quickest route when you know both the target width and the quality you want. Use the dedicated resizer when the dimensions matter enough to want the stepped-down scaling and a choice of output format.