Can I resize in centimetres or millimetres?

Yes. Switch the unit to centimetres and enter the size the form asks for — 3.5 × 4.5 cm is the common passport size. Centimetres only become pixels once a DPI is chosen, so the DPI box appears alongside; 300 is the print standard and 96 is typical for screen. The exact pixel output is shown before you export, so you are not guessing at the conversion. For millimetres, divide by ten: 35 × 45 mm is 3.5 × 4.5 cm.

Does switching between pixels and centimetres change my numbers?

It converts them rather than reinterpreting them. Entering 800 × 600 px and switching to centimetres gives 6.77 × 5.08 cm at 300 DPI — the same physical image described differently. It does not read your 800 as 800 cm, which would be a request for a 94,000-pixel-wide file.

Can it resize and hit a KB limit at the same time?

Yes, and this is the case most forms actually demand: exact dimensions and a maximum file size. Set the dimensions, add a target KB, and the image is resized first and then compressed to fit. If the picture genuinely cannot reach that size at the dimensions you asked for, you are told so with the size it did reach — rather than being handed a file that an upload form will reject.

Will resizing lose quality?

Making an image smaller is safe — detail is discarded, but nothing is invented, and the result is sharp. Making it larger is not: enlarging can only stretch the pixels that exist, so a 200-pixel photo asked for at 2000 pixels comes back soft. Where a form demands a minimum size your original cannot meet, the real fix is a higher-resolution source, not an upscale.

What does 'fit inside box' do?

It preserves the aspect ratio. Your image is scaled to fit entirely within the width and height you gave, so nothing is stretched — which means one side usually lands smaller than the number you typed. A portrait photo fitted into 600 × 600 comes out 522 × 600, not 600 × 600. Turn it off when a form demands exact dimensions and you have already cropped to the right shape.

No. Resizing scales the whole picture; it never cuts anything off. If you need a head-and-shoulders crop to a passport ratio first, use the passport photo maker, then come back here if a further pixel or KB adjustment is needed.

Is there a size limit?

Output is capped at roughly 50 megapixels — around 7000 × 7000 — because beyond that a browser cannot reliably hold the raw pixels in memory and the tab dies. Anything past it is refused as soon as you type it, with the reason, rather than being attempted and failing halfway.

Is my photo uploaded?

No. Your files never leave your device. The resize runs on your own device using your browser's own image handling, which is also why it works on a phone and why there is no file size cap imposed by an upload.

Resize

Resize an image to exact pixels, cm, or KB

Set the size a form actually asks for, and see what you got. Your files never leave your device.

Private by design. Your files never leave your device

Drop an image here, or click to browse

JPG, PNG, GIF, WebP, AVIF, HEIC (Safari/iOS only) — or paste / take a photo

Tip: Ctrl+V / ⌘V to paste

Forms ask in pixels or in centimetres, rarely both

Upload requirements come in two dialects. Government and exam portals usually specify pixels — 600 × 600, or 350 × 450. Print-oriented specifications use physical size — 3.5 × 4.5 cm, or 2 × 2 inches. Enter whichever your form uses and the tool works in that unit.

Centimetres are the ones that catch people out, because a centimetre is not a number of pixels until you decide how densely they are packed. That is what DPI means. At 300 DPI, 3.5 × 4.5 cm is 413 × 531 pixels; at 96 DPI the same physical size is 132 × 170. The tool shows the pixel result before you export, so the conversion is visible rather than assumed. Leave DPI at 300 unless your form says otherwise.

Dimensions and a file size limit, in one pass

The genuinely awkward requirement is the common one: exact dimensions and a maximum file size. Meeting one usually breaks the other, which is how people end up cycling between two different websites and re-uploading the same photo six times.

Set the dimensions, add a target KB, and both are handled together — resized first, then compressed to fit the cap. Where the picture cannot fit that budget at the size you asked for, you are told which size it actually reached and by how much it missed. A tool that quietly hands back 5.2 KB against a 5 KB limit has not helped you; you find out at the upload form, which is the worst possible moment.

Fit inside the box, or exactly the box

Leave fit inside box on and the aspect ratio is preserved: the image is scaled to fit entirely within the width and height you gave, so nothing is squashed. The consequence is that one side lands smaller than the number you typed — a portrait photo fitted into 600 × 600 comes out 522 × 600.

Turn it off when a form insists on exact dimensions and you have already cropped to the right shape. If you have not, turning it off will stretch the picture, which on a face is immediately obvious to whoever reviews it.

Shrinking is safe, enlarging is not

Reducing an image discards detail it no longer needs and stays sharp. Enlarging cannot do the reverse — there is no extra detail to recover, only existing pixels to stretch, so a small photo blown up comes back soft no matter which tool does it.

If a form demands a minimum resolution your photo cannot meet, the only real fix is a better source image: the original from the camera rather than a copy from a messaging app, which will have been downscaled on the way. Upscaling to satisfy the number will usually fail a human reviewer even when it passes the automated check.

Common sizes, and where to go next

If you already know the exact target, these go straight to it: resize image to 50 KB, resize image in cm, passport size photo and 2 × 2 inch photo.

If the dimensions are already right and only the file size is wrong, Compress Image hits a KB target without touching the dimensions. And if you are not certain what the form wants, paste the requirements into the checker and it will read them and tell you what needs changing.

Related tools

Compress Image

Hit a KB limit without changing the dimensions.

Form Photo Checker

Paste the rules; see what fails before you upload.

Passport Photo Maker

Crop to a passport ratio, then size it exactly.

Remove Metadata

Strip GPS and camera data before you share a photo.

Frequently asked questions

Can I resize in centimetres or millimetres?: Yes. Switch the unit to centimetres and enter the size the form asks for — 3.5 × 4.5 cm is the common passport size. Centimetres only become pixels once a DPI is chosen, so the DPI box appears alongside; 300 is the print standard and 96 is typical for screen. The exact pixel output is shown before you export, so you are not guessing at the conversion. For millimetres, divide by ten: 35 × 45 mm is 3.5 × 4.5 cm.
Does switching between pixels and centimetres change my numbers?: It converts them rather than reinterpreting them. Entering 800 × 600 px and switching to centimetres gives 6.77 × 5.08 cm at 300 DPI — the same physical image described differently. It does not read your 800 as 800 cm, which would be a request for a 94,000-pixel-wide file.
Can it resize and hit a KB limit at the same time?: Yes, and this is the case most forms actually demand: exact dimensions and a maximum file size. Set the dimensions, add a target KB, and the image is resized first and then compressed to fit. If the picture genuinely cannot reach that size at the dimensions you asked for, you are told so with the size it did reach — rather than being handed a file that an upload form will reject.
Will resizing lose quality?: Making an image smaller is safe — detail is discarded, but nothing is invented, and the result is sharp. Making it larger is not: enlarging can only stretch the pixels that exist, so a 200-pixel photo asked for at 2000 pixels comes back soft. Where a form demands a minimum size your original cannot meet, the real fix is a higher-resolution source, not an upscale.
What does 'fit inside box' do?: It preserves the aspect ratio. Your image is scaled to fit entirely within the width and height you gave, so nothing is stretched — which means one side usually lands smaller than the number you typed. A portrait photo fitted into 600 × 600 comes out 522 × 600, not 600 × 600. Turn it off when a form demands exact dimensions and you have already cropped to the right shape.
Does it crop?: No. Resizing scales the whole picture; it never cuts anything off. If you need a head-and-shoulders crop to a passport ratio first, use the passport photo maker, then come back here if a further pixel or KB adjustment is needed.
Is there a size limit?: Output is capped at roughly 50 megapixels — around 7000 × 7000 — because beyond that a browser cannot reliably hold the raw pixels in memory and the tab dies. Anything past it is refused as soon as you type it, with the reason, rather than being attempted and failing halfway.
Is my photo uploaded?: No. Your files never leave your device. The resize runs on your own device using your browser's own image handling, which is also why it works on a phone and why there is no file size cap imposed by an upload.