Resize Image Pixels, CM, MM or Inches
Type the width and height you need and this free image resizer changes your image dimensions in pixels, centimetres, millimetres or inches, right in your browser. Lock the aspect ratio so nothing stretches, pick a DPI if you are printing, and download. JPG, PNG, WebP, AVIF or GIF up to 25 MB.
Drop an image here to resize it
JPG, PNG, WebP, AVIF or GIF, up to 25 MB. Resized in your browser, never uploaded.
Two Numbers.
Whatever Unit You Think In.
Every form asks for something different. 1080 pixels wide. 3.5 by 4.5 centimetres. Two inches at 300 DPI. Most resizers only speak pixels and leave you doing arithmetic in another tab, which is exactly where the mistakes come from. Type your requirement in the unit you were given it in, and let the tool do the conversion it was going to do anyway.
Tools that pair well with this one
All free, all in your browser, no signup.
How to resize an image in pixels
Three steps, no account, 25 MB per file.
Select your image
Click the button or drop a JPG, PNG, WebP, AVIF or GIF file onto the box. It stays on your device.
Type your width and height
Pick your unit first, then type one side. With the ratio locked, the other side fills itself in.
Resize and download
Check the before and after, then save it. No watermark, no waiting, no signup.
The default
Resize image pixels, exactly
Pixels are the only dimension an image really has. Everything else on this page is a way of describing them. If a site, a platform or a spec gave you a number in px, type it in the width box and you are done.
The fields open at your image's own size, because the most common edit is making one number smaller and it should take one edit rather than four. Type over the width, and with the ratio locked the height lands on its own.
| Where it goes | Pixel size to type | Why that one |
|---|---|---|
| Instagram post | 1080 × 1080 | Square feed images are served at 1080; anything larger is re-encoded by Instagram anyway |
| Instagram story or Reel cover | 1080 × 1920 | 9:16, the full phone screen |
| YouTube thumbnail | 1280 × 720 | 16:9 at the resolution YouTube asks for, under their 2 MB cap |
| X / Twitter in-feed image | 1600 × 900 | 16:9, sharp on desktop without being wasteful |
| LinkedIn carousel page | 1080 × 1350 | 4:5, the tallest ratio the feed will show without cropping |
| Website hero | 1920 × 1080 | Full HD is still the width most laptops actually render |
| Email header | 600 × 200 | 600px is the safe width across email clients |
Physical units
Resize an image in cm, mm or inches (and what DPI has to do with it)
An image has no physical size on its own. A 600 pixel wide photo is 15.9 cm at 96 DPI and 5.1 cm at 300 DPI, and it is the same photo. So a centimetre only means something once you also say how many pixels go into an inch.
That is the whole reason a DPI control appears the moment you switch away from pixels. It is not a quality setting and it does not change how the image looks on a screen. It is the exchange rate between your unit and pixels, and the tool shows you the pixel result underneath the fields so the conversion is never hidden.
- The formula: pixels = centimetres ÷ 2.54 × DPI. For millimetres, divide by 25.4. For inches, just multiply by the DPI. That is all any of these tools are doing.
- 96 DPI: The screen default, and what a CSS pixel is defined as. Use it when the image is going on a website or into a document that will be read on a screen.
- 300 DPI: What a print lab wants. A 3.5 × 4.5 cm passport photo at 300 DPI is 413 × 531 pixels, and that is the file to send.
- 72 DPI: A legacy default that still shows up in old briefs. Harmless, but 96 is the more honest screen number today.
| Physical size | At 96 DPI | At 300 DPI | Typical use |
|---|---|---|---|
| 3.5 × 4.5 cm | 132 × 170 px | 413 × 531 px | Passport and visa photos |
| 2 × 2 in | 192 × 192 px | 600 × 600 px | US passport photo |
| 5 × 7 cm | 189 × 265 px | 591 × 827 px | Application form photos |
| 10 × 15 cm | 378 × 567 px | 1181 × 1772 px | Standard 4 × 6 in print |
| 21 × 29.7 cm | 794 × 1123 px | 2480 × 3508 px | Full A4 page |
| 35 × 45 mm | 132 × 170 px | 413 × 531 px | The same passport size, in mm |
One thing most browser resizers get wrong: they resize the pixels and then write the file with a 72 DPI tag anyway, so your 5 cm image opens in Word at 20 cm. We write the DPI you chose into the PNG or JPG itself. WebP and AVIF have nowhere to store it, and the tool says so on the result instead of pretending.
Change image dimensions without stretching anything
The aspect ratio lock is on by default, and it is the difference between resizing an image and squashing one. With it on, you type one side and the tool derives the other from your original's proportions.
Turn it off and both fields are yours. That is occasionally what you want, usually when something demands an exact frame and you would rather distort the image than leave it the wrong size. It is worth knowing which one you are doing, because a stretched face is obvious to everyone except the person who stretched it.
- Resizing: Same shape, fewer or more pixels. Ratio locked. Nothing is cut off and nothing is distorted.
- Stretching: Different shape, same content squeezed into it. Ratio unlocked. Circles become ovals.
- Cropping: Different shape, edges removed. Not what this tool does, and it is what you actually need when your source is 4:3 and the slot is 16:9.
| Ratio | Type this width | Get this height | Where it is used |
|---|---|---|---|
| 1:1 | 1080 | 1080 | Instagram posts, profile pictures, product tiles |
| 16:9 | 1920 | 1080 | YouTube, presentations, desktop wallpapers |
| 9:16 | 1080 | 1920 | Reels, Shorts, TikTok, stories |
| 4:5 | 1080 | 1350 | The tallest portrait Instagram will show uncropped |
| 3:2 | 1800 | 1200 | Most DSLR photos, and standard 4 × 6 prints |
| 4:3 | 1600 | 1200 | Phone camera default, older screens, slides |
Reduce image size without losing quality
Resized images look soft for a specific, fixable reason, and it is not the resizer being cheap. It is how a browser draws one image into a smaller canvas.
When a canvas shrinks an image, it samples a small fixed neighbourhood around each output pixel. Ask it to go from 4000 pixels wide to 400 in one move and roughly one source pixel in nine contributes anything at all. The other eight are simply not read. That is where the thin, aliased look comes from: fine detail is not being blurred, it is being skipped.
So this tool does not do it in one move. It halves the image repeatedly until it is close to your target, then makes the final short step. Every pass reads every pixel of the pass before it, which is a cheap approximation of a proper area filter, and it is why text and edges survive a big reduction here.
- Downscaling is nearly free: Removing pixels does not damage the ones that remain. A 25% reduction is visually lossless in any normal viewing situation.
- Upscaling is not: There is no detail to recover, so enlarging invents pixels by interpolation. It will look softer, and the tool warns you before you download rather than after.
- The encoder is the other half: For JPG, WebP and AVIF the quality slider decides how much of the surviving detail gets stored. 90 is the sweet spot: no visible loss, much smaller file.
PNG has no quality setting to expose, which is why the slider disappears for one. A resized PNG is written losslessly, every time.
JPG, PNG, WebP, AVIF and the two honest exceptions
Whatever you upload comes back as the same format, because a resizer's job is to change dimensions and nothing else. There are exactly two cases where a browser makes that impossible, and both of them get said out loud on the result screen rather than discovered later.
| Format | What you get back | Worth knowing |
|---|---|---|
| JPG / JPEG | JPG, with a quality slider | The photo format. The DPI you pick is written into the file's JFIF header |
| PNG | PNG, transparency intact | Lossless. Nothing is flattened onto a white background, ever. The DPI is written as a pHYs chunk |
| WebP | WebP | Keeps transparency and compresses well. No standard place to record DPI, so the pixels are the guarantee |
| AVIF | AVIF, or WebP where the browser cannot write it | Every current browser reads AVIF; not all of them can write it. We test yours rather than guessing, and say which one you got |
| GIF (still) | PNG | No browser canvas can write a GIF at all. PNG keeps every pixel and the transparency |
| GIF (animated) | Declined, with a reason | A canvas only ever sees frame one, so resizing would flatten your animation to a still. We check for extra frames and stop instead |
| HEIC / HEIF | Declined, with a way out | The iPhone default, and no browser can decode it. On iOS: Settings, Camera, Formats, Most Compatible, then re-export |
Why this runs in your browser and not on our server
Most free resizers upload your photo, resize it on a machine you cannot see, and let you download the result. That is a strange amount of trust to ask for a job your own device can do in about 40 milliseconds.
- Private by construction: There is no server to trust with your passport photo, because it never reaches one. That is a stronger guarantee than any privacy policy, including ours.
- Faster: No upload, no queue, no download. On a 6 MB photo the round trip is the entire wait, and we removed it.
- Free to keep free: Your device does the work, so a hundred resizes cost us exactly what zero do. That is why there is no daily cap and no signup wall.
The honest limit: browsers run out of memory eventually. 25 MB per file and 50 megapixels per image is where we stop, because past that a full-resolution decode can take a phone's tab down with no useful error.
A resizer that speaks your units, not just its own.
Because nobody's passport photo requirement was ever written in pixels.
Pixels, centimetres, millimetres, inches
Switch units at any time and the same image is re-described, never re-converted. Your 5 cm stays exactly 5 cm when you flip to inches and back, because pixels are what the tool actually stores.
Lock the aspect ratio
On by default. Change the width and the height follows, so the photo cannot stretch. Turn the lock off when you genuinely need a fixed frame and want the distortion.
DPI that actually gets written to the file
Choose 300 DPI for print and the exported JPG or PNG carries that tag, so Word and Photoshop agree with you about how big it is. Most browser resizers silently ship 72.
Downscales in steps, not one jump
Going from 4000px to 400px in a single draw makes a browser read about one source pixel in nine. We halve repeatedly instead, so every pixel contributes and edges stay sharp.
Your format comes back
A PNG stays a PNG with its transparency. A JPG stays a JPG. The only swaps are the two a browser physically cannot make, and the tool tells you when one happens.
Nothing leaves your device
Decoding, resampling and encoding all happen in your browser. The image is never transmitted, so it cannot be stored, logged or leaked by us or anyone else.
Frequently asked questions
How the resizer works, and where it stops.
Drop your image in, leave the unit on px, and type your number into the width box. With the aspect ratio locked the height fills itself in, so a 1080 wide Instagram post takes one keystroke and a click.
If you need both numbers to be exact and they do not match your image's proportions, turn the ratio lock off. Be aware that is a stretch rather than a resize, so crop to the right shape first if the result matters.
Switch the unit to cm or mm and type your measurement. A DPI control appears next to the fields, because a physical size only becomes a pixel count once you say how many pixels fit in an inch. Use 300 for anything being printed and 96 for anything staying on a screen.
The tool shows you the pixel result under the fields as you type, so a 35 × 45 mm passport photo at 300 DPI visibly becomes 413 × 531 pixels rather than happening behind your back.
300 DPI for print, 96 for screens. And yes, it gets saved: the number you choose is written into the exported PNG or JPG, so opening it in Word, Photoshop or a print dialog gives you the physical size you asked for.
WebP and AVIF have no standard field for it, so those come back with the correct pixel count and no tag. The tool says so on the result rather than leaving you to find out at the print shop.
Not with the aspect ratio lock on, which is the default. Change one side and the other is derived from your original's proportions, so the image is only ever scaled.
Turn the lock off and both fields become independent, which is the only way to get a distorted result here. The tool spells out which mode you are in underneath the fields.
Making an image smaller is close to free. Removing pixels does not harm the ones that stay, and we downscale in repeated halving steps rather than one jump, which is what keeps edges and small text sharp.
Making one bigger is a different story. The detail was never captured, so enlarging can only interpolate, and the result will be softer than the original. The tool warns you before you download when your numbers are larger than the source.
Not here, and that is on purpose. This page changes dimensions. If a form is rejecting your upload for being over 30 KB or 100 KB, what you want is the image compressor, which searches for the highest quality that still fits under a size you type.
The two work well back to back: resize to the dimensions you need first, then compress that result to the file size the form demands.
AVIF, yes. Still GIFs, yes, and they come back as PNG because no browser can write a GIF. Animated GIFs, no: a canvas only ever sees the first frame, so we decline them rather than quietly flattening your animation into a still image.
HEIC is the iPhone default and no browser can open it without a heavyweight decoder. Set your iPhone to Settings, Camera, Formats, Most Compatible, or share the photo to Files and pick JPEG, then drop it back here.
Not yet. One image at a time, with no daily cap and no account. Bulk resizing is on the list, and it will run the same way: in your browser, with nothing uploaded.
No. Decoding, resampling and encoding all happen in your browser using the canvas it already ships with. Your file is read from your device, resized in memory, and handed back. Nothing is transmitted, so nothing can be stored, and closing the tab erases every trace.
Resize your image now
Pick a file, type the width and height you need in any unit, download the result. Nothing gets uploaded.