How to Resize an Image on Windows, Mac, and Online (Free)

The fastest free way to resize an image is an online tool like PicResize or a built-in app: Paint on Windows, or Preview on Mac. You can change pixel dimensions (e.g. 1920×1080 to 800×450) or the file size in megabytes. Just need a smaller file without changing dimensions? See how to reduce image file size.

Method 1: Windows — Paint (built-in)

1. Right-click the image → Open with → Paint.
2. Click Resize in the toolbar.
3. Choose Pixels or Percentage, enter new width/height, and tick Maintain aspect ratio.
4. Click OK, then File → Save As.

Method 2: Mac — Preview (built-in)

1. Open the image in Preview.
2. Tools → Adjust Size.
3. Enter new width or height in pixels (keep Scale proportionally checked).
4. Click OK, then File → Save.

Method 3: Online (any device)

• PicResize — free, no signup
• iLoveIMG — free batch resizing

Upload → enter dimensions → download.

FAQ

How do I resize an image without losing quality?

Always keep aspect ratio locked (the width/height ratio). Resizing down (smaller) keeps quality; resizing up (bigger) makes it blurry.

What size should images be for email?

Keep images under 1–2 MB and around 1200 px on the long side. Most email clients limit attachments to 25 MB total.

How do I resize an image in bulk?

Use iLoveIMG’s batch resize, or on Windows select multiple images → right-click → Resize pictures (PowerToys).

How do I resize an image on my phone?

Use the built-in crop/resize in your Photos app, or a free app like Image Size (iOS/Android) — see how to resize an image on iPhone.