Image Size vs Resolution: Pixels, KB, MB and DPI
“Image size” can mean several different measurements, and each one requires a different change.
Pixel dimensions
Width and height describe the number of pixels in the image, for example 1200 × 800. Multiplying them gives the total pixel count. Pixel dimensions control how much screen detail the file can contain.
File size in KB or MB
KB and MB describe storage size. Format, compression quality, metadata and visual complexity all affect the number of bytes. Reducing dimensions often lowers file size, but two files with identical dimensions can still have very different KB values.
Megapixels and aspect ratio
Megapixels are the total pixel count divided by one million. Aspect ratio describes the shape, such as 4:3, 3:2 or 16:9. Cropping changes aspect ratio and may also reduce megapixels.
DPI and print size
DPI is mainly a print instruction. A 3000-pixel-wide image printed at 300 DPI is about 10 inches wide. Changing DPI metadata alone usually does not create more screen detail or change the pixel dimensions.
Choose the right action
Use a size checker to inspect the file, a resizer to change pixels, a compressor to meet a KB limit, and a cropper to change composition or aspect ratio.
- Exact pixels required: use Image Resizer
- Maximum KB required: use Image Size Reducer
- Unknown file properties: use Image Size Checker
- Different composition required: use Crop Image