Image Size Calculator
The uncompressed size of an image from its pixels and colour depth, its megapixels, and its print size at a DPI.
Your image
Filled in with example values. Replace them with your own.
Optional
How large the image prints at a resolution in dots per inch.
Results update as you type.
Result
6000 × 4000 px at 24 bits per pixel: 72 MB (68.66 MiB) uncompressed, 24 MP
Uncompressed size
72 MB
- In binary units
- 68.66 MiB
- Megapixels
- 24 MP
How it’s calculated
Pixels
6,000 × 4,000 = 24,000,000
Bytes
24,000,000 × 24 ÷ 8 = 72,000,000
How the image size calculator works
An image is a grid of pixels, and each pixel takes a fixed number of bits to store its colour. Multiplying the number of pixels by the bits per pixel gives the uncompressed size: what the image takes up in memory or in an uncompressed file.
Add a print resolution in DPI to see how large the image prints.
The formula
Bytes = Width × Height × Bits per pixel ÷ 8
Print width = Width in pixels ÷ DPI
Worked examples
- A 6000 × 4000 photo at 24-bit colour: 24,000,000 pixels × 3 bytes = 72 MB (68.66 MiB) uncompressed. At 300 DPI it prints at 20 × 13.33 inches.
- A 1920 × 1080 screenshot with transparency (32-bit): 2,073,600 × 4 bytes = 8.29 MB.
Frequently asked questions
Why is my JPEG much smaller than this?
This calculator gives the size of the raw pixels. JPEG, PNG and WebP compress them, often to a small fraction of that size, by an amount that depends on the picture and the quality setting. A busy, detailed photo compresses less than a plain one.
What colour depth should I choose?
Most photos and screenshots are 24-bit colour (8 bits each for red, green and blue). Add transparency and it is 32-bit. Professional editing and scanning often use 48-bit (16 bits per channel).
What DPI do I need for printing?
It depends on the printer and how closely the print will be seen; print services usually state the resolution they want. The calculator shows the print size at whatever DPI you enter.
What is a megapixel?
One million pixels. A 6000 × 4000 image has 24,000,000 pixels, so 24 megapixels.