ON A MAC
- Open your image in Preview.
- Select Tools > Adjust Size. This will bring up the Resize dialog, which will allow you to resize the image.
- Choose your desired measurement unit (inches, pixels, etc.) and your desired resolution.
- Once you’re done, select File > Save As and save your resized image.
ON WINDOWS
- Open your image in Windows Photo Gallery.
- Select Edit > Properties > Resize.
- Click the Select A Size list and select a size. For a custom size, in the Maximum Dimensions box, enter the maximum width you desire.
- Click Resize and save to save your resized image.
Please note, use RGB for anything dealing with the web (social icons, emails, etc.). Use CMYK for any printed material (collateral, business cards, etc.).