A hero image for a blog
Input 4032 × 3024, width 1200 px, JPEG.
Result 1200 × 900 — the same 4:3 ratio, ready for a 1200 px content column.
Image Resizer
Files & UtilitiesResize a photo to an exact width, height or percentage and download it in JPG, PNG or WebP — the aspect ratio is kept and nothing is uploaded.
Your inputs
Result
Resized image
—
- Preview —
- New size —
- Original —
- New file —
Change any input and the result updates instantly.
Formula and rules
- By width: new height = original height × new width ÷ original width
- By percentage: both sides × scale ÷ 100
- Inside a box: scale = min(1, box width ÷ image width, box height ÷ image height)
- The ratio is always preserved, so the result is never stretched or squashed
- Images smaller than the requested size stay at their original size instead of being enlarged
Worked examples
Half size for email
Input 2400 × 1600, scale 50%.
Result 1200 × 800 and a quarter of the original pixel count.
Fit a portrait photo in a square slot
Input 2000 × 3000, box 800 × 800 px.
Result 533 × 800, so the whole photo fits inside the box without cropping.
FAQ
Will resizing make the file smaller?
Usually, yes — especially when you shrink. A 4032 px photo cut to 1200 px has about a ninth of the pixels, so the file shrinks dramatically even at high quality. Enlarging always makes the file bigger without adding detail.
Why is the result a pixel off from what I typed?
The other side is calculated from the ratio and rounded to a whole pixel, because fractional pixels cannot be stored. For 4:3 at 1200 px wide you get exactly 900, but 1000 px gives 750 — odd ratios may round by one pixel.
Can I upscale a small image?
You can, with the width, height or percentage modes, but scaling up never adds real detail — the browser just interpolates pixels, so the result looks soft. Start from the largest original you have.
Does it keep transparency?
PNG and WebP do. JPEG has no alpha channel, so transparent areas are filled with white — pick PNG if you need the cut-out to stay transparent.
Disclaimer: Files are processed inside your browser only. Nothing is uploaded or stored on a server, and the result disappears when you reload or close the page — download the file you need first.