Image planning & checks
Image Size Calculator
Separate pixel dimensions, raw pixel memory, print dimensions and encoded KB/MB targets before you compress or resize an image.
Image Size Calculator
Compare pixel count, raw memory, print size and a target byte budget.
What this calculator separates
Useful for
- Planning image uploads with both dimension and size limits
- Estimating canvas memory before browser processing
- Checking print dimensions before export
- Choosing whether to resize, compress or do both
How to calculate image size
- 1
Enter pixel dimensions
Use the actual or planned width and height.
- 2
Enter DPI when relevant
Use the printer or destination density requirement.
- 3
Enter a target KiB value
Use the byte ceiling required by the upload destination.
- 4
Compare the measurements
Use dimensions for canvas requirements and the target bytes for encoded-file planning.
Important limits
- • Raw RGB/RGBA estimates are not predictions of JPG, PNG, WebP or AVIF file size.
- • Encoded file size depends on image detail, format, transparency and compression settings.
- • DPI affects physical size calculations; it does not automatically change pixel dimensions.
- • KiB uses 1,024 bytes. Some websites label decimal KB differently.
Encoded file size cannot be predicted from pixels alone
Two images with identical dimensions can produce very different compressed file sizes because codecs respond to detail, noise, transparency and quality settings.
Use this calculator for planning, then use the compressor for a real target-size output and verify the downloaded file.
Frequently asked questions
Can pixel dimensions tell me the exact JPG file size?
No. JPG size also depends on image content and quality settings. Pixel dimensions only establish the canvas.
What is the difference between KB and pixels?
Pixels describe image dimensions; KB describes encoded storage size. Upload forms can impose both requirements.
Why show RGB and RGBA estimates?
They are useful approximations of raw pixel memory before compression: roughly three bytes per RGB pixel or four bytes per RGBA pixel.
Should I resize or compress first?
Meet the required pixel dimensions first, then compress the resulting image to the required byte limit.
Related image tools
Inspect dimensions, file size, format, aspect ratio and megapixels from an image.
Read an image ratio and calculate matching dimensions without stretching.
Create a new image at the pixel dimensions required by your destination.
Reduce encoded file size after you have chosen the right dimensions.