The fastest way depends on what device you're using and what you need the image for

On a Windows computer, right-click the image file, select "Open with," and choose Photos or Paint. In Photos, click the three dots menu and look for a crop or resize option. In Paint, go to Image > Resize and Image Skew, then enter your new width and height in pixels. On a Mac, open the image in Preview, click Tools > Adjust Size, and enter your dimensions. On an iPhone or Android phone, use the built-in Photos app — open the image, tap Edit, and look for a crop tool that lets you change dimensions. For web use, you can also upload images to free sites like Pixlr or Canva without installing anything.

The key difference is between cropping (cutting away parts of the image) and resizing (making the whole image larger or smaller). Resizing down to a smaller size usually looks fine. Resizing up to a larger size often makes the image blurry, so avoid that unless you have no choice. If you're preparing an image for a website, email, or social media, smaller file sizes load faster — resizing down accomplishes that.

Key Takeaways

  • Windows users can resize images in the built-in Paint app by going to Image > Resize and Image Skew, then entering new pixel dimensions.
  • Mac users open images in Preview, click Tools > Adjust Size, and type the width and height they want.
  • Phone users can crop and resize photos directly in the Photos app without downloading anything extra.
  • Making an image smaller usually looks good; making it larger often causes blurriness, so resize down when possible.
  • Free online tools like Pixlr and Canva let you resize images in a web browser if you don't want to install software.

Resizing in Windows Paint

Open the image file in Paint — right-click it, select "Open with," and choose Paint from the list. If Paint doesn't appear, click "More apps" to find it. Once the image is open, click the Image menu at the top, then select "Resize and Skew."

A dialog box will appear with fields for Horizontal and Vertical size. By default, the "Maintain aspect ratio" box is checked, which means if you change the width, the height adjusts automatically to keep the image from looking stretched. Leave this checked unless you have a specific reason to distort the image. Enter your new width or height in pixels, then click OK. The image will resize, and you can save it by pressing Ctrl+S or going to File > Save As to keep the original.

Resizing on a Mac using Preview

Open the image in Preview — it's the default app for images on Mac. Click the Tools menu at the top, then select "Adjust Size." A window will pop up showing the current width and height in pixels or inches, depending on what you've selected.

Make sure the chain link icon between width and height is connected (locked), so the proportions stay the same when you change one dimension. Type your new width or height, and the other will adjust automatically. If you want to change the resolution (dots per inch), you can do that here too, but for most purposes you only need to change the pixel dimensions. Click OK when you're done, then save the file using File > Export As.

Resizing photos on iPhone or Android

Open the Photos app and select the image you want to resize. Tap Edit (on iPhone) or the pencil icon (on Android). Look for a crop tool — on iPhone it's usually a square with corner marks; on Android it may say "Crop" directly. Tap it to enter crop mode.

You'll see handles around the image that let you drag the edges inward to make the image smaller. Some phones also let you tap a menu to enter specific dimensions, but dragging the corners is usually the simplest method. When you're happy with the size, tap Done or Save. The app will save the edited version, and you can usually undo the change later if you need the original back.

Using free online tools if you don't want to install software

Pixlr and Canva both let you upload an image and resize it in your web browser without downloading anything. Go to Pixlr.com or Canva.com, click the option to open or upload an image, and look for a resize or scale option in the menu. Enter your new dimensions and download the result.

These tools are useful if you're on a computer that isn't yours or if you want to resize multiple images quickly. They also often include basic editing features like cropping, rotating, and adjusting brightness. The trade-off is that you're uploading your image to someone else's server, so avoid these tools if the image contains private information.

Understanding pixels, inches, and file size

Most resize tools let you choose between pixels and inches. Pixels are the tiny dots that make up a digital image — a 1920 × 1080 image is 1920 pixels wide and 1080 pixels tall. Inches are a physical measurement, and the relationship between inches and pixels depends on the resolution (dots per inch, or DPI). For screen use like email or websites, work in pixels. For printing, work in inches and make sure the DPI is at least 300 to avoid blurriness.

File size (measured in kilobytes or megabytes) depends on both the image dimensions and the file format. A JPEG file is usually smaller than a PNG file of the same image. Resizing down reduces file size, which matters if you're uploading to email or a website with size limits. If you need to shrink file size without changing dimensions, you can also compress the image, which reduces quality slightly but keeps the pixel dimensions the same.

Why resizing down works better than resizing up

When you resize an image down, the software throws away pixels, so the image stays sharp. When you resize up, the software has to guess what new pixels should look like between the existing ones, which usually creates a blurry or blocky result. This is why it's better to start with a large image and make it smaller than to start small and try to enlarge it.

If you find yourself needing to enlarge a small image, consider using an AI upscaling tool like Upscayl (free) or Topaz Gigapixel (paid), which use machine learning to guess what details should appear when enlarging. These work better than standard resizing, but they're not perfect and work best on photos rather than graphics with text.

Frequently Asked Questions

What's the difference between resizing and cropping?

Resizing makes the entire image larger or smaller while keeping all the content. Cropping cuts away the edges to remove parts of the image. You can do both — crop first to remove unwanted parts, then resize the result to your final dimensions.

Will resizing an image make it blurry?

Resizing down (making it smaller) usually looks fine. Resizing up (making it larger) often causes blurriness because the software has to guess what pixels should fill the new space. If you must enlarge an image, use an AI upscaling tool for better results than standard resizing.

What size should I use for social media or email?

For email, 800 to 1200 pixels wide is standard and keeps file size reasonable. For social media, each platform has different recommendations — Instagram prefers 1080 × 1080 for square posts, Facebook prefers 1200 × 628 for cover images. Check the platform's help section for exact specs.

Can I resize multiple images at once?

On Windows, you can use batch processing software like IrfanView or XnConvert (both free) to resize many images to the same size in one operation. On Mac, Automator can do this too. Online tools like Pixlr also let you upload multiple files, though you may need to resize them one at a time.

What file format should I use after resizing?

JPEG is best for photographs because it compresses well and keeps file size small. PNG is better for images with text or graphics because it preserves sharp edges. WebP is newer and smaller than both, but not all devices support it yet. Save in the format that matches your original image unless you have a reason to change it.