Resize Image in MM
Enter the width and height in millimetres — the unit most photo and label specs use — and get a print-ready file with the DPI saved inside. Everything runs in your browser — nothing is uploaded. Need a smaller file instead? Compress or convert.
Drag the preview to choose which part of the image is kept. The same framing is used for every image in the batch.
How to resize an image
Resizing changes the pixel dimensions of an image — making it fit a specific width, a percentage of the original, or a platform's required size. Smaller dimensions also mean a smaller file, which is why resizing is one of the most effective ways to speed up a page.
- Add your images, or drop them in.
- Choose By dimensions for an exact width and height, By percentage to scale, or a Preset for common social and screen sizes.
- Click Resize, then download each file or grab them all as a ZIP.
Exact or proportional
Set precise pixels with aspect-ratio lock, scale by percentage, or pick a preset. Whatever the target needs.
Batch, instantly
Resize a whole folder at once to the same dimensions. No upload wait, no queue, no file limit.
Nothing is uploaded
Your images are resized by your own browser and never sent to a server, so they stay completely private.
Resize for a specific platform
Jump to a common size:
Other image tools:
Will resizing reduce quality?
Making an image smaller is safe — you are discarding pixels you no longer need, and the result looks clean. Making an image larger than its original is where quality suffers, because the browser has to invent pixels that were never there, which looks soft or blocky.
As a rule: resize down freely, but avoid scaling up much beyond the original dimensions. If you need a smaller file rather than smaller dimensions, use the compressor instead.
Square sizes
Same width and height — profile photos, icons, product shots:
Landscape sizes
Wider than tall — screens, banners, covers and thumbnails:
Portrait sizes
Taller than wide — passport photos, forms and phone screens:
Change the aspect ratio
Paper, print & photo sizes
Paper and photo sizes in mm, cm and inches, plus DPI tools:
Resize for a platform
Ready-made sizes for social profiles and posts:
Resize tools
Batch resizing, DPI and crop tools:
Why photo and label specs use millimetres
Passport rules, label templates and die-cut stickers are specified in millimetres because a millimetre or two matters. This page lets you type those numbers directly instead of converting them yourself.
The maths: pixels = mm ÷ 25.4 × DPI. At 300 DPI, 35 mm is 413 pixels and 45 mm is 531 pixels.
Decimals are fine. Type 38.1 or 50.8 exactly as the spec shows; the tool rounds to whole pixels.
Check the print. Print at 100% ("actual size") and measure with a ruler. If it is off, the print dialog scaled it — not the file.
Common mm sizes: 35×45, 33×48, 50×70, 51×51. For centimetres use resize in cm.
More ways to resize
Other units and tools for the same job:
Frequently asked questions
How many pixels is 1 mm?
About 11.8 pixels at 300 DPI, 5.9 at 150 DPI, and 3.8 at 96 DPI.
What is the difference between resizing and compressing?
Resizing changes the dimensions (the width and height in pixels). Compressing keeps the dimensions but reduces the file size by lowering quality. Resizing down does both at once, which is why it is so effective. For file size alone, use the compressor.
Will the aspect ratio be kept?
In dimensions mode, tick "Keep aspect ratio" and set just the width or height — the other is calculated automatically so the image is not stretched. Untick it to force exact dimensions, which may distort the image.
Can I resize many images at once?
Yes. Drop in as many as you like and they are all resized to the same setting in one go, then you can download them together as a ZIP. There is no limit on how many.
Are my images uploaded?
No. Resizing happens entirely in your browser. Nothing is transmitted or stored, and you can disconnect from the internet after the page loads and it still works.
Which format will I get back?
Images keep their original format where the browser supports it (JPG, PNG, WebP). Formats a browser cannot write, like GIF or BMP, come back as PNG. To change format on purpose, use the converter.