Image Resizer Online: Exact Pixels, MM or CM (Free, No Upload)
Portals do not only check weight; they check dimensions. "35 x 45 mm at 300 DPI" or "600 x 600 pixels" are dimension rules, and a resizer that only speaks pixels cannot answer them directly.
This one speaks all three units and shows the resulting pixel box before you commit, so a print rule and a pixel rule become the same operation.
Pixels, MM and CM are one maths
Physical size plus DPI equals pixels: 35 mm at 300 DPI is 413 pixels across. The resizer does that conversion for you: pick MM or CM, type the physical numbers, set DPI, and the pixel box updates live.
Aspect lock keeps proportions unless you deliberately break them; unlocking is there for the rare rule that demands a stretched box.
Step by step
- Add the image; current pixels and physical size at 300 DPI are shown.
Choose the unit the rule is written in (Pixels, MM or CM) and type the target.
Check the computed pixel dimensions and the lock state.
Download the resized file; the DPI metadata is written so print shops read the intended physical size.
Upsizing versus downsizing
Downsizing throws pixels away and is always safe. Upsizing invents pixels: simple interpolation softens edges, which is fine for screen previews but visible in print. For genuine detail recovery use the upscaler tool instead of the resizer when the jump is large.
For ID and visa rules, never upsize a tiny crop to meet a pixel minimum; re-crop from the source photo instead.
Checks that save a rejection
- Read the rule's unit carefully: pixels, mm and cm are different columns on the form.
Confirm the pixel box the tool computes before downloading.
For print rules keep DPI at the stated value (usually 300) and change only physical size.
Batch mode applies the same target per file with per-file outputs.
Try it free: Image Resizer | runs entirely in your browser, no uploads and no signup.