How to Use the Aspect Ratio Resolution Converter
When editing video or designing a banner or thumbnail, keeping the correct aspect ratio prevents your image from looking stretched or squished. 16:9 is the standard widescreen ratio used by YouTube and modern TVs, 4:3 was the classic ratio for older CRT televisions and some presentation slides, and 21:9 is used for ultrawide monitors and cinemascope movie screens. Enter your target ratio along with one known side — either width or height — and this tool instantly calculates the other side.
For example, entering a width of 1920px at a 16:9 ratio calculates a height of 1080px, giving you the familiar Full HD resolution. If you know the height instead, you can calculate the matching width just as easily.
Common Aspect Ratios and Their Resolutions
- 16:9 → 1920x1080 (Full HD), 3840x2160 (4K)
- 4:3 → 1024x768, common presentation ratio
- 21:9 → 2560x1080, ultrawide monitors
- 9:16 → 1080x1920, vertical short-form video
Whether you're resizing a video source for a different platform or producing banner ad creative in multiple ratios, calculating exact pixel dimensions ahead of time with this tool saves you back-and-forth in your editing software.
Frequently Asked Questions
At a 16:9 ratio, a width of 1920px gives a height of 1080px. This is the standard ratio for Full HD (1920x1080) resolution.
21:9 is used for ultrawide monitors and cinemascope movie screens. It produces a much wider frame than the standard 16:9 ratio.