How this calculator works
A 16:9 frame is sixteen units wide for every nine units high. Video names use the height, so 1080p is 1920 pixels across and 1080 down, and 2160p is the 3840 by 2160 frame sold as 4K UHD. Each standard in the table is exactly 16:9, which means you can scale any of them by a whole number and keep the shape. Entering one side works the same way: the missing side is the known side multiplied by the other ratio term. A pixel result that is not a whole number should be rounded to the nearest pixel, which can be a fraction of a percent away from the ideal shape.
Formula
height = width x 9 / 16. width = height x 16 / 9. total pixels = width x height. megapixels = total pixels / 1,000,000. The ratio is always 16:9, or 1.777778 when the width is divided by the height.
Worked example
A Full HD frame is 1920 by 1080 pixels. If you know only the 1920 width, the height is 1920 x 9 / 16 = 1080. The frame holds 2,073,600 pixels, or about 2.07 megapixels. Scaling the same shape to 4K UHD multiplies both sides by two: 3840 by 2160, which is 8,294,400 pixels or 8.29 megapixels. A smaller 1280 by 720 clip is 0.92 megapixels but still 16:9.
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Frequently asked questions
Why is 4K called 4K when the width is 3840 pixels?
The name comes from the cinema DCI 4K frame of 4096 pixels across. Consumer 4K UHD is 3840 by 2160, which is exactly 16:9 and slightly narrower than the cinema version.
What happens when 16:9 video is shown on a 4:3 screen?
The player either adds black bars above and below the picture, called letterboxing, or crops the sides. Letterboxing keeps the whole frame visible; cropping fills the screen but loses the edges.
Is 1366 by 768 a true 16:9 resolution?
No. It is close, but 1366 divided by 768 is about 1.7786 rather than 1.7778. Panel makers round laptop and monitor resolutions, so the reduced ratio is 683:384 rather than 16:9.
Can a 16:9 frame be rotated to portrait?
Yes. Rotating the frame gives 9:16, the shape used by phone video, stories and short-form video. The pixel count and the shape are unchanged; only the orientation differs.