Resizing vs compressing
These solve different halves of the same problem and work best together. Resizing throws away pixels you do not need. Compression keeps the pixel count and spends fewer bytes describing them.
| Reach for | When | Typical saving |
|---|---|---|
| Resizing | The image is far larger than the space it is shown in | Large — halving the width usually quarters the file |
| Compression | Dimensions are already right but the file is still heavy | Moderate — often 40–70% with no visible change |
| Changing format | You are still serving PNG or JPG where WebP would do | Often 25–35% versus JPEG at similar quality |
Do them in that order. Resize first, because compressing a 4000-pixel image you are about to shrink to 800 wastes the effort. Then compress what is left, and convert the format if the destination supports something more modern.
Pixels or percentage?
- Pixels when something downstream demands an exact size: a theme that wants a 1200px hero, a marketplace with a minimum edge length, a print spec.
- Percentage when you have a batch of mixed-size photos and simply want them all smaller. Every image keeps its own proportions.
Not sure what size the slot actually is? The website image checker scans a live page and reports the rendered size of every image on it, which is the number you want to resize toward.
Frequently Asked Questions
How do I resize an image online?
Drop the image into the tool above, choose either exact pixel dimensions or a percentage to scale by, and press Resize. The work happens in your browser, so nothing is uploaded and the resized file downloads straight back to you. Leave "Lock aspect ratio" on and you only need to set the width.
Does resizing reduce the file size?
Yes, substantially. File size tracks pixel area rather than width, so halving the width of an image quarters its pixel count and usually cuts the file to roughly a quarter. That makes resizing the single most effective way to shrink an oversized photo before compression is even considered.
Are my photos uploaded to a server?
No. Decoding, resampling and re-encoding all run in a Web Worker on your own device using WebAssembly builds of the standard image libraries. You can confirm it by opening your browser Network tab while resizing — no request carries the file.
Will resizing make my image blurry?
Scaling down is safe and stays sharp. Scaling up is not: enlarging past the original pixel dimensions makes the browser invent pixels it does not have, which looks soft. If you need a larger image, start from a larger original rather than upscaling this one.
Can I resize several images at once?
Yes, up to 20 at a time. In percentage mode each image scales by the same proportion. In pixel mode with the aspect ratio locked, each image is fitted to your target width and keeps its own height ratio, so mixed-shape batches do not get distorted.
What size should I resize my image to?
Match the space it will actually occupy, then roughly double it for high-density screens. An image displayed in a 400 pixel wide slot wants a source around 800 pixels wide. Going far beyond that downloads pixels no one will ever see.
Related tools and guides
- Image cropper — reframe rather than rescale, with aspect-ratio locks.
- Social media image resizer — crop to exact Instagram, X, LinkedIn and Pinterest sizes.
- Image compressor — shrink the file without changing dimensions.
- Image converter — change format between JPG, PNG and WebP.
- How to reduce image file size — the full decision order.
- Recommended image sizes for websites — what to resize toward.