Image Aspect Ratio & DPI Converter
Enter a photo's pixel dimensions to get its simplified aspect ratio, a matching width or height for a target ratio, and its physical size in inches or centimeters at a given DPI. Nothing is uploaded — this reads only the numbers you type.
Print suitability is a general rule-of-thumb guideline (300 DPI ≈ photo-print quality, 150 DPI ≈ usable for larger or less critical prints), not a guarantee for any specific printer or paper. No image file is read, uploaded, or stored — only the numbers you type.
A 4000 × 3000 px listing photo, checked at 300 DPI: Aspect ratio: gcd(4000, 3000) = 1000 → 4000/1000 : 3000/1000 = 4:3 Width in inches: 4000 / 300 ≈ 13.33 in Height in inches: 3000 / 300 ≈ 10.00 in In centimeters: 13.33 × 2.54 ≈ 33.87 cm, 10.00 × 2.54 = 25.4 cm At 300 DPI this reads as photo-print quality up to that physical size.
How to use this calculator
- Enter the photo's pixel width and height.
- Optionally click a preset ratio (1:1, 3:2, 4:3, 16:9, 9:16) and enter a target width or height to see the matching dimension for that ratio.
- Enter the DPI/PPI you're printing or exporting at to see the physical size and a general print-suitability note.
- Use "Copy result" to copy a plain-text summary, or "Reset" to start over.
How the calculation works
The aspect ratio is reduced with the greatest common divisor of the width and height — a 4000×3000 image reduces to 4:3 the same way 8:6 would. Given a target ratio and one fixed dimension, the other dimension is solved by cross-multiplication. Physical size divides pixel count by DPI to get inches, then multiplies by 2.54 to get centimeters. A DPI of zero or a blank field is rejected before it can produce a division-by-zero result.
FAQ
Does this tool read my actual photo file?
No — it only works from the pixel numbers you type in. No file is selected, uploaded, or sent anywhere.
Is DPI the same thing as PPI?
Not technically — PPI (pixels per inch) describes the image file, DPI (dots per inch) describes a printer's output — but they're commonly used interchangeably for this kind of estimate, which is why this tool treats them as one input.
Why would I need a specific aspect ratio for a listing photo?
Different platforms and print templates crop to fixed ratios — knowing the matching width or height ahead of time avoids an awkward last-minute crop that cuts off part of a room.