Home › Tools › Pixel Calculator
Pixel Calculator
Enter any image size in pixels to get its megapixels, simplified aspect ratio, orientation, print size at your DPI, and an estimated uncompressed file size. Everything runs in your browser — no image is uploaded anywhere.
Print size uses the formula inches = pixels ÷ DPI, then × 2.54 for centimetres. The file-size estimate is width × height × 3 bytes (24-bit colour, uncompressed) — a real JPG or PNG will usually be much smaller.
Frequently asked questions
What is a megapixel?
One megapixel is one million pixels. Multiply width by height: a 4000 × 3000 photo has 12,000,000 pixels, which is 12 megapixels.
What does DPI change in this calculator?
DPI only changes the print size. The pixel count stays the same. At 300 DPI a 350 × 450 px photo prints about 2.96 × 3.81 cm; at 150 DPI the same photo prints twice as large, about 5.92 × 7.62 cm, because fewer dots are packed into each inch.
Why is the estimated file size different from my JPG size?
The estimate is the raw, uncompressed size (width × height × 3 bytes for colour). A JPG or PNG compresses that data, so the real file is almost always much smaller. The estimate is useful for comparing images, not for predicting an exact JPG size.
What aspect ratio is 350 × 450?
Divide both numbers by their greatest common divisor. 350 and 450 share 50, so the ratio is 7:9. This calculator does that step for any size you enter.