How to use the image size checker
- 1 Drop one or more images on the box.
- 2 Read the dimensions, file size, megapixels and aspect ratio in the table.
- 3 Check the print size at 300 dpi.
- 4 If a file is too large, use the compress or resize tools.
Meeting size limits
Forms usually set two limits: dimensions in pixels and file size in KB. Fix the pixels with Resize Image in Pixels and the file size with Compress Image. Check again here before uploading.
- Dimensions are not changed by compression; file size is.
- Print at 300 dpi for sharp photos, 150 dpi for posters seen from afar.
- Phone screenshots often have very large pixel sizes.
Features
Full details
Pixels, KB or MB, megapixels, ratio, type and print size.
Many files
Check a whole folder at once.
HEIC and SVG
Reads iPhone photos and SVG graphics too.
When to use it
Upload forms
Check that a photo meets limits such as 600 × 600 pixels and under 100 KB before submitting. Too large? Use Compress Image.
Websites
Make sure images are not far larger than they are displayed. Resize with Resize Image.
Printing
See how big a photo can print sharply at 300 dpi.
Social media
Check aspect ratios before posting.
Related Image tasks
Frequently asked questions
How do I find the dimensions of an image?
Drop it here and read the width and height in pixels. On Windows you can also right-click, choose Properties and Details.
What is the difference between dimensions and file size?
Dimensions are the number of pixels wide and tall; file size is how much storage it takes, in KB or MB. Compression changes the file size without changing the dimensions.
What does megapixels mean?
Millions of pixels: width times height divided by one million. A 4000 × 3000 photo is 12 megapixels.
How is the print size worked out?
Pixels divided by 300, the usual dots per inch for good prints, then converted to centimetres.
What aspect ratio do phones use?
Most phone cameras take 4:3 photos; widescreen video is 16:9.
Is 1 KB 1,000 or 1,024 bytes?
This tool shows sizes using 1,024 bytes per KB, the same as Windows.
Can it read the camera details?
Not yet; it focuses on size. Camera and EXIF details are planned for a separate viewer.
Why does my image look small on my screen but have a big file size?
File size depends on detail and compression, not just dimensions. A detailed photo saved at high quality can be several megabytes even at a modest size.
How do I reduce the dimensions?
Use the resize tools to set a new width and height in pixels, or the compress tools to reduce the file size while keeping the dimensions.
Can I check images on my phone?
Yes. Open this page in your mobile browser and choose photos from your gallery to see their exact size.
Are my images uploaded to check their size?
No. The browser reads only the file details and pixel size on your device, so nothing is uploaded or stored.
How this tool works. These image tools run entirely in your browser using the Canvas API built into every modern browser, the open-source libheif decoder for iPhone HEIC photos and Tesseract, a widely used open-source OCR engine, for reading text. Each tool is tested with real phone photos, screenshots and scans before it goes live, and nothing you open is sent to a server.
Built and reviewed by Hamza Farooq, founder and lead developer
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