How to check image dimensions
Select an image and the browser decodes its intrinsic width and height. Pixel dimensions describe the fixed grid of color samples in the file. For example, a 4000 × 3000 image contains 12 million pixels, or 12 megapixels.
What the aspect ratio tells you
Aspect ratio describes the proportional relationship between width and height. A 4000 × 3000 photo reduces to 4:3. Resizing it to another 4:3 dimension preserves the composition; placing it in an 8 × 10 print, which is 4:5, requires cropping or borders.
| Ratio | Common dimensions | Typical use |
|---|---|---|
| 1:1 | 1080 × 1080 | Square graphics |
| 4:3 | 4000 × 3000 | Cameras and screens |
| 3:2 | 6000 × 4000 | Photography |
| 4:5 | 2400 × 3000 | 8 × 10 prints |
| 16:9 | 1920 × 1080 | Widescreen video |
Image size is not the same as file size
Dimensions measure pixels. File size measures stored bytes and depends on format, compression, metadata, transparency, and image complexity. Two 4000 × 3000 files can have very different file sizes while sharing the same dimensions.
Frequently asked questions
Does checking an image change it?
No. ToolFoundry reads the selected file and creates a temporary local preview. It does not modify or upload the original.
Are megapixels width plus height?
No. Multiply width by height, then divide by one million. A 4000 × 3000 image is 12 megapixels.
Why is the ratio not a familiar number?
Some crops and exported assets use uncommon proportions. The checker reports the exact reduced integer ratio rather than forcing it into the nearest preset.