Resize image in mm (convert to pixels)
To resize by millimeters, convert mm to inches, then to pixels using DPI.
Conversion formulas
- inches = mm ÷ 25.4
- pixels = inches × DPI
Common DPI values
- 72–96 DPI for screens
- 300 DPI for print
DPI only affects print size, not pixels.
3 steps (using this tool)
- Convert mm to pixels using DPI.
- Enter pixel size in the resizer.
- Export JPG/PNG locally.
Example
35×45 mm at 300 DPI → 413×531 px.
Related guides
Physical size
Resize in cm/inches →Use this when the spec is given in larger physical units, so you can switch between mm and cm/inches cleanly.
Pixels
Resize in pixels →Use this when the output needs exact digital dimensions, so the exported file matches screen-based requirements.
Converter
Image size converter →Use this when you need to compare mm with px and file size limits, so you can choose the right workflow quickly.
FAQ
How do I convert mm to pixels?
Convert mm to inches (mm ÷ 25.4), then multiply by DPI.
Quick tip: Use 300 DPI for print, 72–96 DPI for screens.
Common mistake: Skipping DPI—print size will be wrong.
Can I resize in mm online?
Yes—convert to pixels and enter the px size in the resizer.
Quick tip: Use presets for common pixel sizes.
Common mistake: Entering mm directly without conversion—wrong size.
Does DPI change quality?
DPI doesn’t add pixels; it only changes print size.
Quick tip: Quality improves with more pixels, not higher DPI alone.
Common mistake: Expecting DPI to sharpen a small image.
Do you upload my images?
No. Processing happens locally in your browser. Your files are not uploaded.
What size should I use?
Use the recommended size.
Which export format should I use?
JPG for photos, PNG for text/logos or transparency, WebP for smaller files (if supported).
Crop vs Pad — what is the difference?
Crop fills the target size (may cut edges). Pad fits the whole image and adds background/space.
How do I protect text and logos?
Keep important content centered and avoid placing critical text at the edges.
Can I batch resize?
Yes. Use the Batch Resizer to apply the same size to many images.