UlvixorImage Size Calculator
Upload an image to see its real width, height, file size, and aspect ratio, and use the built-in calculator to get new dimensions while keeping the original proportions. Handy before resizing an image in your favorite editor. Everything happens in your browser — the file is never uploaded to a server.
How it works
- Select an image from your device using the file picker.
- Your browser loads the image and reads its real dimensions in pixels along with its file size on disk.
- The simplified aspect ratio is calculated and shown (for example, 16:9).
- Enter a target width or height in the calculator, and the other value is calculated automatically to keep the proportions.
Use cases
- Calculate the exact dimensions before resizing an image in Photoshop, GIMP, or Canva.
- Verify that an image meets a platform's size requirements (social media, banners, thumbnails).
- Check whether an image is in a standard aspect ratio (16:9, 4:3, 1:1) before using it.
- Plan a set of responsive images by calculating the corresponding height for different widths.
Use cases
- Calculate the exact dimensions before resizing an image in Photoshop, GIMP, or Canva.
- Verify that an image meets a platform's size requirements (social media, banners, thumbnails).
- Check whether an image is in a standard aspect ratio (16:9, 4:3, 1:1) before using it.
- Plan a set of responsive images by calculating the corresponding height for different widths.
Common mistakes
- Expecting the tool to generate and download an already-resized image.This tool only calculates the resulting dimensions while keeping the proportions; it doesn't produce a new file. Use those values in your image editor, or in this site's Image Compressor or Image Converter, to apply the actual change.
- Changing width and height separately in an image editor expecting the image not to distort.If you change both values without respecting the original ratio, the image stretches or squishes. Use the width or height calculated here, which always keeps the original aspect ratio.
- Confusing a file's 'weight' (in KB or MB) with its dimensions in pixels.They're two different things: file size depends on compression and format, while dimensions are the actual width and height in pixels. This tool shows both separately to avoid the confusion.
Frequently asked questions
No. It only calculates the resulting dimensions while keeping the original proportions; it doesn't generate or download a resized image. For that, you can use this site's Image Compressor or Image Converter, or your preferred image editor with the values calculated here.
No. The image is loaded locally in your browser using an Image object and a temporary URL generated with URL.createObjectURL(). It's never sent to any server.
If you enter a target width, the height is calculated by multiplying that width by the original height/width ratio (and vice versa if you enter a height), rounded to the nearest pixel.
Any format your browser can display natively: JPEG, PNG, WebP, GIF, SVG, and other common web formats.
Alternatives
You can check an image's dimensions by right-clicking → Properties → Details on Windows, or with Cmd+I in macOS Preview. This tool adds the ratio calculation so you know ahead of time what height corresponds to a target width (or vice versa), without doing the cross-multiplication by hand.