How Do I Resize an Image? A Step-by-Step Guide for Web, Mobile, and Print

Resizing an image changes its pixel dimensions (width and height) to better fit a purpose, whether that’s speeding up web load times, matching print specifications, or preparing images for social media.

Key difference:

• Resizing alters dimensions
• Resampling (optional) adds or removes pixel data
• Aspect ratio determines whether the image keeps its original proportions

1. Open the image in Paint
2. Click the Resize button
3. Choose between percentage or pixels
4. Maintain aspect ratio (optional)
5. Click OK, then Save

1. Open image in Preview
2. Go to Tools > Adjust Size
3. Enter new width and height
4. Save the resized image

Apps like Snapseed, Photoshop Express, or Photo Resizer (iOS/Android) make it easy to resize on the go.

These options are great for beginners and fast edits, though they lack batch capabilities or advanced options.

Online tools are user-friendly and ideal for quick resizing when you don’t have local software installed.

• Cloudinary
• Canva
• Adobe Express
• ILoveIMG
• Image Resizer
• Pixlr

1. Upload your image
2. Choose resize method: by pixel, percentage, or aspect ratio
3. Adjust dimensions (e.g., width, height, DPI)
4. Download the resized version

⚠️ Tip: Some online tools may reduce image quality or compress your image. Be cautious with sensitive or high-fidelity files.

For more precise control and quality preservation, professional editors are ideal.

1. Open your image
2. Go to Image > Image Size
3. Adjust pixel dimensions or use %
4. Maintain aspect ratio using the chain-link icon
5. Resample (optional): Select methods like Preserve Details 2.0
6. Click OK and Save

1. Open the image
2. Go to Image > Scale Image
3. Enter new size
4. Choose interpolation method (e.g., Cubic or Sinc for quality)
5. Apply and save

These tools are great for high-quality resizing, creative edits, or print-specific settings.

If you’re automating workflows or building applications, libraries in Node.js or Python make image resizing efficient.

    const sharp = require('sharp');
    sharp('input.jpg')
      .resize(600, 400)
      .toFile('output.jpg');Code language: JavaScript (javascript)

from PIL import Image

img = Image.open("input.jpg")

img = img.resize((600, 400))

img.save("output.jpg")Code language: JavaScript (javascript)

If you’re managing tons of images or want automated, responsive resizing, Cloudinary is the best cloud-based solution.

• Resize on the fly using URL parameters
• Preserve aspect ratio automatically
• Smart cropping, fitting, and padding
• Real-time delivery optimized for each device and screen
  

<img 
src="https://res.cloudinary.com/demo/image/upload/w_400,h_300,c_fill/sample.jpg" 
alt="Resized Image">Code language: HTML, XML (xml)

This dynamic URL uses three features:

• w_400 for width
• h_300 for  height
• c_fill crops to fit image to it’s new size

Try Cloudinary’s transformation demo

• Maintain aspect ratio to avoid distortion
• Use lossless formats (like PNG or TIFF) when quality matters
• For web, aim to keep file sizes under 200 KB for performance
• DPI settings matter for print but not for web
• Save a copy of the original before resizing

Use Case	Best Option
Quick edits	Built-in tools (Paint, Preview)
No installation	Online resizers (Canva, Img2Go, Adobe Express)
High quality or print	Photoshop, GIMP
Backend automation	Node.js (Sharp), Python (Pillow)
Responsive, scalable delivery	Cloudinary

Whether you’re resizing a photo for your blog or batch-processing assets for an e-commerce site, the right method depends on your needs.

Get started with Cloudinary to dynamically resize, crop, and optimize your images for every screen, without lifting a finger.