How to Resize Image in cm or mm
Use our unit converter to set exact dimensions in centimeters or millimeters for official forms. Perfect for SSC, UPSC, Banking exam photos where dimensions are given in cm.
cm / mm Support
Enter dimensions in centimeters or millimeters
Auto Conversion
Automatically converts to pixels at 300 DPI
Maintain Aspect Ratio
Lock proportions to avoid stretching
100% Private
All processing in browser
📏 Why Resize in cm or mm?
Most government exam forms and official documents specify photo dimensions in centimeters or millimeters:
SSC Exams
Photo: 4.0 x 2.0 cm
Signature: 4.0 x 2.0 cm
UPSC
Photo: 2.0 x 2.0 inches
Signature: 3.5 x 1.5 cm
Railways
Photo: 3.5 x 4.5 cm
Signature: 3.5 x 1.5 cm
NEET
Photo: 4.0 x 3.0 cm
Signature: 4.0 x 2.0 cm
📊 Unit Conversion Reference
| Centimeters (cm) | Millimeters (mm) | Inches (in) | Pixels (300 DPI) |
|---|---|---|---|
| 1.0 cm | 10 mm | 0.39 inches | 118 px |
| 2.0 cm | 20 mm | 0.79 inches | 236 px |
| 3.0 cm | 30 mm | 1.18 inches | 354 px |
| 4.0 cm | 40 mm | 1.57 inches | 472 px |
| 5.0 cm | 50 mm | 1.97 inches | 591 px |
* Based on standard 300 DPI (dots per inch) for print quality
🔢 The Math: How Pixels are Calculated
Formula: Pixels = (Centimeters × DPI) ÷ 2.54
Since 1 inch = 2.54 cm, and standard print DPI = 300
For 4.0 cm at 300 DPI:
Pixels = (4.0 × 300) ÷ 2.54 = 472 pixels
📝 Step-by-Step Resize Guide
Go to Image Resizer
Open your browser and visit: imresizer.in
[Screenshot: Image Resizer homepage with upload area]
⬆️ Main resizer tool with unit selector
Upload Your Image
Click the upload button and select the image you want to resize:
- Formats: JPG, PNG, WEBP, GIF, BMP
- From anywhere: Phone camera, gallery, or computer
[Screenshot: File upload dialog]
📱 Upload from any device
Select Unit (cm or mm)
This is the key step for exam photos:
Centimeters (cm)
SSC, Banking, NEET
Millimeters (mm)
UK, Europe, Australia
- Look for the unit dropdown (px/cm/mm/in)
- Select "cm" or "mm" based on your requirement
[Screenshot: Unit dropdown showing cm selected]
📏 Choose cm or mm from dropdown
Enter Exact Dimensions
Enter the required dimensions from your exam form:
- Width: Enter in cm or mm (e.g., 4.0 for SSC photo)
- Height: Enter in cm or mm (e.g., 2.0 for SSC photo)
- DPI: Keep at 300 (standard for print/exam photos)
| Exam | Width | Height | Unit |
|---|---|---|---|
| SSC | 4.0 | 2.0 | cm |
| UPSC | 2.0 | 2.0 | inches* |
| Railways | 3.5 | 4.5 | cm |
| UK Passport | 35 | 45 | mm |
* UPSC uses inches, but you can select "inches" from same dropdown
[Screenshot: Width and height fields with 4.0 and 2.0 entered]
✏️ Enter exact dimensions as per exam requirement
Click Resize
- Click the "Resize" or "Apply" button
- Wait 2-3 seconds for processing
- Preview the resized image
[Screenshot: Resize button with preview]
⏳ Processing your image
Download & Verify
- Click "Download" to save your image
- Right-click the downloaded file → Properties/Get Info
- Check dimensions under "Details" tab
- Verify they match your required cm/mm size
[Screenshot: Download button with file properties showing dimensions]
✅ Verify dimensions before uploading to exam portal
📱 Mobile Instructions
Resize images on your phone:
- Open imresizer.in in Chrome/Safari
- Tap upload and select photo from gallery
- Tap unit dropdown and select "cm" or "mm"
- Enter width and height
- Tap "Resize" and wait
- Tap "Download" - saves to your phone
🎯 Real-World Examples
📄 SSC Exam Photo (4.0 x 2.0 cm)
Steps:
- Upload your photo
- Select unit: cm
- Enter width: 4.0
- Enter height: 2.0
- Lock aspect ratio (to prevent stretching)
- Resize and download
📄 UK Passport Photo (35 x 45 mm)
Steps:
- Upload your photo
- Select unit: mm
- Enter width: 35
- Enter height: 45
- Resize and download
📄 UPSC Photo (2 x 2 inches)
Steps:
- Upload your photo
- Select unit: inches (available in same dropdown)
- Enter width: 2.0
- Enter height: 2.0
- Resize and download
⚠️ Important Tips
- DPI matters: Always use 300 DPI for exam photos (our default)
- Check both dimensions: Some exams have different width and height
- After resizing: You may need to compress to meet file size limits (use compressor)
- Verify before upload: Always check dimensions in file properties
Common Mistake
Don't confuse cm and mm! 4.0 cm is NOT the same as 4.0 mm. 4.0 cm = 40 mm. Always double-check your exam notification for the correct unit.
🔒 Privacy & Security
Your Images Are Safe
- 100% Client-Side: All resizing happens in your browser
- No Server Uploads: Your images never leave your device
- No Data Storage: We don't keep any copies
- HTTPS Secure: Encrypted connection
❌ Common Problems & Solutions
| Problem | Solution |
|---|---|
| Image looks stretched | Enable "Maintain aspect ratio" before resizing |
| Wrong unit selected | Check dropdown - cm vs mm vs inches |
| Dimensions not matching after download | Verify DPI is set to 300 |
| File size too large after resize | Use compressor to reduce KB |
| Can't find cm option | Look for unit dropdown near width/height fields |
❓ Frequently Asked Questions
Q: How do I convert cm to pixels?
A: Our tool does it automatically. At 300 DPI, 1 cm = 118 pixels. Formula: (cm × 300) ÷ 2.54
Q: What is the difference between cm and mm?
A: 1 cm = 10 mm. So 4.0 cm = 40 mm. Always check which unit your exam uses.
Q: Can I resize in inches as well?
A: Yes! The dropdown includes inches option for UPSC and US requirements.
Q: What DPI should I use for exam photos?
A> 300 DPI is standard for all exam photos. Our tool uses this by default.
Q: Will resizing reduce quality?
A: No, our tool maintains quality. If you need smaller file size, use compressor after resizing.
Q: Can I resize multiple photos at once?
A: Currently, our tool handles one photo at a time for precise dimensions.
📚 Related Resources
🚀 Resize Your Image Now
👉 Ready to resize in cm or mm?
Set exact dimensions for your exam photos. Free, no registration, 100% private.
Open Image Resizer →📌 Quick Checklist Before Resizing:
- ✅ Know your required dimensions (check exam notification)
- ✅ Confirm unit (cm, mm, or inches)
- ✅ Lock aspect ratio to prevent stretching
- ✅ After resize, verify dimensions in file properties
- ✅ Compress if file size exceeds limit
⭐ Bookmark this guide for all your exam photo resizing needs!