How to Resize an Image to Exact Pixels or File Size
Resize an image to exact pixel dimensions without stretching it, or shrink it under a file size limit such as 100 KB, with a free in-browser image resizer.
Published
Free tool: Image ResizerUpload forms, websites and email all have their own size rules: "at least 600 × 600 pixels", "under 200 KB", "1200 pixels wide". Resizing an image to fit is quick once you know the difference between pixel dimensions and file size, and how to change one without spoiling the picture. This guide explains both, with examples, using the free Image Resizer.
Pixels, file size and print size
- Pixel dimensions are the image's width and height in pixels, such as 4032 × 3024 for a typical 12-megapixel phone photo. This is what "resize" usually means.
- File size is how much storage the image takes, in kilobytes (KB) or megabytes (MB). It depends on the number of pixels, the file format and the compression.
- Print size depends on how many pixels you spread over each inch. At 300 pixels per inch, the usual standard for good-quality prints, an image 3000 pixels wide prints 10 inches wide. A file's DPI setting alone doesn't change its pixels.
Keep the proportions
To resize without stretching or squashing, change the width and height by the same proportion:
New height = new width × (original height ÷ original width)
- A 4032 × 3024 photo resized to 1200 pixels wide becomes 1200 × 3024 ÷ 4032 = 900 pixels tall.
- A 1920 × 1080 image resized to 1280 wide becomes 720 tall.
If you need a different shape, such as a square profile picture from a rectangular photo, crop it first with the Crop Image tool, then resize. Changing both numbers independently distorts faces and circles.
Common sizes
| Use | Typical width |
|---|---|
| Full-width website banner, Full HD screen | 1920 px |
| Image inside a blog post or article | 1200 px |
| Email newsletter image | 600 px (a common email template width) |
| Thumbnail or profile picture | 300–400 px |
Social networks and online forms change their requirements from time to time, so check the current numbers where you're uploading.
Don't make images bigger
Shrinking an image keeps it sharp, because there's more detail than you need. Enlarging it can't add detail that isn't there, so a small image stretched to twice its size looks soft or blocky. If you need a larger image, go back to the original file.
How to resize an image with Graph Maker
- Open the Image Resizer and add your image by dragging it onto the page or clicking to choose a file. You can also paste a direct link to an image online. The tool shows the original size.
- Enter the new width or height. The boxes start at the original dimensions. With Aspect Ratio Locked (the default), changing one number updates the other automatically. Click it to unlock only if you really want to change the shape.
- Set a target file size if you need one. Type a number of kilobytes in Target File Size, or leave it blank.
- Choose the output format: the same as the original, JPG, PNG or WebP.
- Click Process Image. The preview shows the result and its new file size.
- Download the resized image, or click Try Again to change the settings.
The image is resized in your browser, so files from your device aren't uploaded anywhere. If you choose JPG for an image with a transparent background, the tool saves it as PNG instead, because JPG can't store transparency.
Resizing to a file size limit
Forms often cap uploads at a size such as 100 KB or 2 MB. To get under a limit:
- Reduce the dimensions first. A document photo rarely needs more than about 1000 pixels on its longest side.
- Pick JPG or WebP and enter the limit as the target file size. To reach it, the tool lowers the compression quality and, if it has to, the dimensions as well, so check the final size it reports.
- Avoid PNG for photos when you need a small file. PNG is lossless, so the only way to make it much smaller is to use fewer pixels.
If you need exact pixels and a size limit, as some ID photo forms require, enter the exact dimensions, choose JPG and set a realistic target, then check the result. For tighter savings across many images at once, the Image Compressor handles batches; see How to Compress Images Without Visible Quality Loss.
Resize, crop or compress?
- Resize changes the pixel dimensions of the whole image.
- Crop cuts away the edges to change the framing or shape, keeping the remaining pixels as they are. Use Crop Image, or the Aspect Ratio tool to fit a set ratio such as 16:9.
- Compress keeps the dimensions but stores the image more efficiently, making the file smaller.
Frequently asked questions
Does resizing an image reduce its quality?
Making an image smaller keeps it looking sharp at its new size. Making it larger makes it look blurry, because no new detail is created. Saving as JPG or WebP adds some compression, which is usually invisible at sensible settings.
How do I resize an image to under 100 KB?
Reduce the width to around 800 to 1200 pixels, choose JPG, and enter 100 as the target file size. The tool adjusts the compression to fit, and shows the final size before you download.
How do I resize an image without stretching it?
Keep the aspect ratio locked, so the height changes in proportion to the width. If you need a different shape, crop the image first.