Aspect-ratio calculator
Work out the simplified aspect ratio (like 16:9 or 4:3) from any width and height — useful for identifying a standard ratio or checking a crop.
Result
Simplified ratio
Width ÷ height
How to use this tool
- Enter a width and height, in any consistent unit (pixels, cm, inches).
- Read the simplified ratio.
Assumptions
- Rounds width and height to whole numbers before simplifying — very precise non-integer dimensions may not simplify to a perfectly clean ratio.
Technical details: what the fields mean
- Width
width - The width measurement, in any unit — pixels, cm or inches all work as long as width and height use the same unit.
- Height
height - The height measurement, in the same unit as width.
Methodology
Divides both width and height by their greatest common divisor (GCD), giving the simplest whole-number ratio.
Worked example
1920×1080
Inputs: Width: 1920, Height: 1080
Result: 16:9 (1.78)
A 6000×4000 camera photo
Inputs: Width: 6000, Height: 4000
Result: 3:2 (1.50) — the classic 35mm-film shape, so a 6×4-inch print needs no cropping.
A portrait phone photo, 3024×4032
Inputs: Width: 3024, Height: 4032
Result: 3:4 (0.75) — width first, so portrait ratios come out below 1.
An 'ultrawide 21:9' monitor at 2560×1080
Inputs: Width: 2560, Height: 1080
Result: 64:27 (2.37). '21:9' is a marketing label; 21 ÷ 9 is 2.33, close but not exact.
A 1366×768 laptop screen
Inputs: Width: 1366, Height: 768
Result: 683:384 (1.78) — not a clean ratio, but the decimal shows it's effectively 16:9.
Practical guidance
- Common standard ratios: 16:9 (widescreen video), 4:3 (older TV/photo), 3:2 (35mm photo), 1:1 (square).
- When the simplified ratio looks odd, compare the decimal instead: 1.78 is 16:9, 1.33 is 4:3, 1.50 is 3:2.
- To fit an image to a different ratio you have to crop or add borders; resizing alone always keeps the original ratio.
Common mistakes
- Assuming any width/height combination will simplify to a 'clean-looking' standard ratio — many real images and crops don't match a standard ratio exactly.
- Swapping width and height, which turns 16:9 into 9:16 (a vertical video).
FAQs
What aspect ratio is 1920x1080?
16:9 — the standard widescreen video ratio.
Why does my image give a strange ratio like 683:384?
Its dimensions aren't an exact multiple of a standard ratio. The decimal (here 1.78) shows which standard it's closest to.
What ratio is a 6×4 photo print?
3:2 — the same as most camera sensors, so camera photos print at 6×4 without cropping.
Last reviewed: 2026-09-25
Rounds inputs to whole numbers before simplifying — very precise measurements may show a ratio that doesn't look 'clean'.
This tool provides an indicative estimate, based on the assumptions stated above.
Theme and tool preferences, along with saved and recently used lists, are stored only in this browser.