Aspect Ratio Calculator
What ratio is 1920×1080? How tall is a 16:9 video at 2560 wide? Find the ratio of any dimensions, or solve for the missing one — without stretching anything.
Aspect ratio
16:9
16:9 (HD/4K video, monitors)
Decimal
1.778
width ÷ height
Common resolutions: 1920×1080 and 3840×2160 are 16:9, 2560×1080 is 21:9 (true ultrawide cinema is 64:27), 3000×2000 is 3:2. Resizing without keeping the ratio is what stretches or squashes an image.
Aspect Ratios in Practice
An aspect ratio is just the width-to-height fraction reduced to lowest terms — 1920×1080 divides by 120 to give 16:9. Resizing keeps the image undistorted only when both dimensions scale by the same factor, which is why a 16:9 video letterboxes on a 4:3 screen instead of stretching: the alternative is circles becoming ovals.
Common ratios & resolutions
16:9 1280×720, 1920×1080, 2560×1440, 3840×2160 4:3 640×480, 1024×768, 2048×1536 (iPad) 21:9 2560×1080, 3440×1440 (ultrawide) 3:2 3000×2000 (photo, Surface) 9:16 1080×1920 (Stories, Reels, TikTok) Missing dimension: height = width × ratioH ÷ ratioW
Frequently Asked Questions
What aspect ratio is 1920×1080?
16:9 — both numbers divide by 120. The whole 16:9 family scales the same way: 1280×720 (÷80), 2560×1440, 3840×2160 (4K). If a resolution doesn't reduce to a familiar pair, it's probably a slightly-off panel size like 1366×768.
How do I resize an image without distorting it?
Scale both dimensions by the same factor — or fix one dimension and compute the other from the ratio (height = width × ratio-height ÷ ratio-width). Any photo editor's 'lock aspect ratio' checkbox does exactly that math; the solve mode here does it when you need the number explicitly.
Why does my video have black bars?
The video's ratio doesn't match the screen's, and the player letterboxes (bars top/bottom) or pillarboxes (bars at the sides) rather than stretch. A 21:9 movie on a 16:9 TV letterboxes; a vertical 9:16 phone clip on the same TV pillarboxes hard. Bars preserve geometry — stretching makes circles into ovals.
Is 1366×768 really 16:9?
Almost but not exactly — it reduces to 683:384, about 1.779 versus 16:9's 1.778. The format came from budget panel manufacturing, and the mismatch is invisible in practice; content made for 16:9 displays on it with at most a single row of pixels' difference.