Image & Photo
Aspect Ratio Calculator
Find the aspect ratio of any width × height, or calculate a missing dimension for 16:9, 4:3, 21:9 and custom ratios.
W : H = (W ÷ GCD) : (H ÷ GCD)
Also called aspect ratio · 16:9 calculator
Tech & Media · 10 calculators
Image & Photo Calculators
Image aspect ratios, resolution, DPI and PPI, print sizes, pixels to inches, resizing, megapixels and file size.
Image & Photo
Image Resolution Calculator
Megapixels, aspect ratio and print size for any image dimensions.
megapixels = width × height ÷ 1,000,000
Also called image size calculator · megapixel calculator
Image & Photo
DPI Calculator
Dots per inch from pixel dimensions and print size, with the quality verdict.
DPI = pixels ÷ inches
Also called dots per inch calculator · print dpi
Image & Photo
PPI Calculator
Screen pixel density from resolution and diagonal size, with the viewing distance it suits.
PPI = √(width² + height²) ÷ diagonal in i…
Also called pixels per inch · screen density calculator
Image & Photo
Print Size Calculator
Largest good-quality print from an image, at any DPI, in inches and centimetres.
print inches = pixels ÷ DPI
Also called photo print size · max print size calculator
Image & Photo
Pixels to Inches Converter
Convert pixels to inches, centimetres and millimetres at a given DPI.
inches = pixels ÷ DPI
Also called px to inches · pixel to cm
Image & Photo
Inches to Pixels Converter
How many pixels a physical size needs at a chosen DPI, for print or screen.
pixels = inches × DPI
Also called inch to px · cm to pixels
Image & Photo
Image Resize Calculator
New image dimensions that keep the aspect ratio, from a target width, height or percentage.
new height = new width ÷ original aspect …
Also called aspect ratio resize · proportional resize calculator
Image & Photo
Megapixel Calculator
Convert between megapixels and image dimensions for any aspect ratio.
megapixels = width × height ÷ 1,000,000
Also called mp calculator · megapixels to resolution
Image & Photo
Image File Size Calculator
Estimated file size for an image from its dimensions, format and compression.
size ≈ pixels × bits per pixel ÷ 8, scale…
Also called photo file size · jpeg size calculator
Key image & photo formulas
| Aspect Ratio | W : H = (W ÷ GCD) : (H ÷ GCD) · H = W × b ÷ a |
|---|---|
| Image Resolution | megapixels = width × height ÷ 1,000,000 |
| DPI | DPI = pixels ÷ inches |
| PPI | PPI = √(width² + height²) ÷ diagonal in inches |
| Print Size | print inches = pixels ÷ DPI |
| Pixels to Inches Converter | inches = pixels ÷ DPI |
| Inches to Pixels Converter | pixels = inches × DPI |
| Image Resize | new height = new width ÷ original aspect ratio |
| Megapixel | megapixels = width × height ÷ 1,000,000 |
| Image File Size | size ≈ pixels × bits per pixel ÷ 8, scaled by the compression quality |
Image & Photo questions
What are the common aspect ratios?
16:9 for HD video and most monitors, 4:3 for older TVs and iPads, 21:9 for ultrawide displays, 1:1 for square social posts, 9:16 for vertical video and 3:2 for many camera sensors.
How many megapixels do I need for a print?
For a good 12 × 8 inch print at 300 DPI you need about 8.6 MP. Large prints viewed from a distance need far fewer.