How to use the Image Size Checker
Choose the picture
Drop a file on the box, or choose one from this device. For an address, use the paste button or the keyboard, then press Check URL.
Read the pixel size
The large number is the width and height the image size checker read. Under it are the simplified ratio, the megapixels, and the file size when the browser can read the bytes.
Leave the file here
A file you choose is read in this browser and is not posted to this site. An address is fetched by your browser from that host.
Summarize with
Key features
Read on this device
A file you drop is decoded in this browser. The image size checker does not post it to a server this site runs.
A file or an address
Use a picture stored on this device, or paste an https address when the file is already online.
Formats this browser can open
JPEG, PNG, WebP, GIF, BMP and SVG. If the browser cannot decode the file, the page says so instead of inventing a size.
The ratio sits beside the pixels
Width and height become a simplified ratio and a megapixel count, so the calculator and the converter already have a shape to work from.
Pixels are not the file size
The image size checker reports two different facts. Width times height is the pixel grid, such as 1920×1080. File size is how many bytes that file occupies, such as 240 KB. A 5×7 print is a useful picture of the first number: it is the space the picture takes up. The second number is closer to how heavy the file is to store or to send.
The same 1920×1080 grid can be a small JPEG or a much larger PNG. The ratio stays 16:9 either way. Compression changes the bytes. It does not change the shape. When a page is slow, the bytes are the usual cause. When a crop looks wrong, the pixel grid is the cause. The resolution calculator starts from that grid. It does not open the file.
What a browser does with PPI
People ask for resolution when they want to know whether a picture will look sharp. On a screen, the pixel grid is the part that draws. An 800×600 picture tagged 72 PPI and an 800×600 picture tagged 300 PPI occupy the same rectangle in a browser. The tag is metadata. The browser does not resample the file to honor it.
PPI is pixels per inch on a panel. The PPI calculator divides the diagonal of the pixel grid by the viewable inches. DPI is the print instruction. The DPI to pixel calculator multiplies paper inches by that number. 8×10 inches at 300 DPI is 2400×3000 pixels. That 300 matters at the printer. It does not make an 800×600 web image sharper.
This image size checker can tell you the pixel grid. It does not invent a print DPI, because a file often stores a default tag that was never a print decision.
Format changes the bytes
JPEG throws away detail to stay small, which suits photographs. PNG keeps every sample and can keep transparency, so logos and screenshots are often larger. WebP can do either job and is usually the smaller file for a page. GIF is for short loops and a limited color set, not for a photograph. SVG is drawing instructions. Its width and height may come from the viewBox rather than a bitmap, and a scaled SVG stays sharp.
The type line on the image size checker is the type the browser reports. Renaming the extension does not change it. If a page needs fewer bytes, change the format or the pixel grid in an editor. This page does not recompress the picture, and it does not write a new file.
What to do with the size
The width and height from the image size checker are enough to continue on this site. The homepage calculator simplifies the pair, or gives the missing side when you already know the ratio. The converter shows the crop and the pad when the destination shape is different: 1920×1080 into 9:16 is a side crop or a tall canvas, not a stretch. YouTube and Instagram name the frames those uploads expect.
A slow page is usually a large file, not a wrong ratio. Cut bytes before you change the shape. If the brief is a print, take the pixel grid to the DPI tool instead of trusting a 72 PPI tag that came along with the camera.
Frequently asked questions
Does the image size checker upload my picture?
No. A file you choose is read in your browser and is not posted to this site. If you paste an address, your browser requests that picture from the host in the address.
Which formats can it read?
JPEG, PNG, WebP, GIF, BMP and SVG, plus any other type your browser can decode. A format the browser cannot open, such as some HEIC files, returns an error instead of a size.
Is there a file size limit?
There is no fixed cap. A very large file can stall the tab while the browser decodes it. The pixel size is the decoded width and height, not a guess from the byte count.
Why is file size missing for a URL?
Some hosts let the browser display the picture but not read the bytes. Width and height still appear. File size appears when the host allows the read, and it always appears for a file you choose on this device.
Does it resize or crop the picture?
No. It reports the size. Crop and pad numbers are on the converter, and they are pixel targets, not a new file.
Can I use it on a phone?
Yes. Choose a photo from the device, or paste an image address. The same page is the desktop tool.