How to Resize an Image Online Free

Resizing changes an image’s pixel dimensions. This is different from compression — compression reduces file size while keeping dimensions the same. You need to resize when an image is too large for its destination, or when a platform has specific dimension requirements.


Resize Images Free with AllMediaTools

  1. Open AllMediaTools Image Compressor.
  2. Upload your image.
  3. Set Max Width and/or Max Height in pixels.
  4. Enable Maintain Aspect Ratio to scale proportionally.
  5. Click Compress / Resize and download.

Standard Image Dimensions by Platform

Platform / useRecommended size
YouTube thumbnail1280×720px
Facebook cover851×315px
Instagram post (square)1080×1080px
Instagram Stories / Reels1080×1920px
Twitter/X header1500×500px
Website hero (full-width)1920×1080px
Blog post / Open Graph image1200×630px
Email header600px wide
Email signature logo200–300px wide

Built-In OS Methods

Windows — Paint

Open in Paint → Home → Resize → Pixels → enter Width → OK → File → Save As.

Mac — Preview

Open in Preview → Tools → Adjust Size → set Width (height locks automatically) → File → Export.


The Correct Web Image Workflow

  1. Resize to max display width (e.g. 1200px for blog posts)
  2. Convert to WebP using AllMediaTools Image Converter
  3. Compress to under 100KB using AllMediaTools Image Compressor

Frequently Asked Questions

What’s the difference between resizing and cropping?

Resizing scales the full image proportionally. Cropping removes parts of the image to change composition or match a specific aspect ratio. Most tools offer both.

Can I make an image larger without losing quality?

Standard upscaling always reduces sharpness — software invents pixel data that wasn’t there. AI upscalers (Topaz Gigapixel, ESRGAN) produce better results for enlargement. For print, always start with the highest resolution source.

Does resizing reduce file size?

Yes — significantly. A 4000×3000px image has 12 million pixels; a 1200×900px version has 1.08 million — 91% fewer pixels to store. See our guide: How to Compress Images Without Losing Quality.

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