Before you resize an image, upload it or fix an error, you often need two numbers: its dimensions in pixels and its file size. Every device can show you both, you just have to know where to look.
On Windows
- Right-click the image file.
- Choose Properties.
- Open the Details tab.
Under Image, you’ll see Dimensions (such as 4000 x 3000) and under File, the Size. You can also hover over a file in File Explorer to see a tooltip with dimensions and size, and add those columns in the Details view.
On Mac
- Get Info: select the file and press Cmd + I. Look under More Info for dimensions, and at the top for size.
- Preview: open the image and choose Tools > Show Inspector. The first tab shows pixel dimensions and size.
On iPhone
Open the photo in the Photos app, then swipe up (or tap the info button) to see details like file name, size and dimensions. The resolution and file size appear in the info panel for most photos. It’s also a place to see location data. See what is EXIF data.
On Android
Open the photo in your gallery or Google Photos, then tap the info icon or swipe up. You’ll find the resolution (often in megapixels and pixel dimensions) and file size. The layout varies by phone brand.
In a web browser
For an image on a website:
- Quick look: right-click and choose Open image in new tab. Many browsers show the natural dimensions in the tab’s title bar.
- Developer tools: right-click the image, choose Inspect, and hover over the img tag. A tooltip shows both the displayed size and the “intrinsic” (real file) size.
- File size: in the Network tab of developer tools, reload the page, filter by Img and look at the size column.
Comparing real size with displayed size tells you whether you’re sending more pixels than needed. See how to audit website images.
Reading the numbers
- Dimensions: width x height in pixels. This determines how detailed the image is. See what is image resolution.
- File size: kilobytes (KB) or megabytes (MB). 1 MB is about 1,000 KB. This determines upload limits and loading time.
The two are related but not the same, as explained in image dimensions vs file size.
Common mix-ups
- Windows may show file size in KB and “size on disk” differently. Use the Size figure.
- Megapixels are not dimensions. A 12 MP photo is about 4000 x 3000. See how many megapixels you need.
- A screenshot of an image has the dimensions of your screen capture, not the original.
Need to send a photo under a size limit? See making photos smaller for text messages.
Once you know the numbers, use our free image resizer to bring them to what your form or website needs.