Aspect Ratio Calculator
Resize without stretching the picture.
Aspect Ratio Calculator
Height = Width × (ratio height / ratio width); Width = Height × (ratio width / ratio height)
Calculated instantly
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What This Calculator Does
The Aspect Ratio Calculator keeps an image, video, or canvas in proportion. Enter the ratio and one known dimension, and it returns the matching other dimension, the ratio as a decimal, and the megapixel count.
How It Works
An aspect ratio is width divided by height. To keep it, multiply the known dimension by the ratio term for the other side. If you know the width, height is width times ratio height over ratio width; if you know the height, width is height times ratio width over ratio height.
Example
For 16:9 with a 1920 px width, the matching height is 1920 × 9 / 16 = 1080 px, which is 2.07 megapixels. Going the other way, a 1080 px height gives 1080 × 16 / 9 = 1920 px. A 1000 px width would need 562.5 px, so round to 563 and accept a fraction of a percent of distortion.
Formula
Height = Width × ratio height / ratio widthWidth = Height × ratio width / ratio heightMP = Width × Height / 1,000,000Reading the Results
Height that matches this width
The height that preserves the ratio at your width. Round to a whole pixel and check that the visible difference is acceptable.
Megapixels at the known width
Total pixel count, useful for estimating file size, memory use, and whether a crop still has enough resolution.
Sources and References
ITU-R BT.709 — Parameter values for HDTV
16:9 aspect ratio for high-definition television
BT.709 established 16:9 as the HDTV production and display ratio.
W3C — CSS Values and Units Level 4
aspect-ratio property
CSS now lets layout preserve an intrinsic ratio, which is the same arithmetic applied by the browser.
References identify the method or data behind this calculator. Where a standard or tariff changes, the current edition applies, and the assumptions stated above take precedence over a remembered figure.
Frequently Asked Questions
What is the difference between 16:9 and 16:10?
16:9 is wider and is the standard for video and most modern displays. 16:10 is slightly taller and was common on laptops because it leaves more vertical room for documents and toolbars.
How do I resize an image without distortion?
Change only one dimension and let the other follow the ratio, or crop instead of stretching. If you must hit an exact pixel size, crop the excess rather than scaling each axis independently.
Why is my computed dimension a decimal?
Most ratios do not divide the chosen width evenly. 16:9 at 1000 px gives 562.5. Round to the nearest whole pixel; the resulting ratio differs by a fraction of a percent, which is invisible.
What ratio should I use for social video?
Vertical 9:16 for Reels, Shorts, and TikTok, square 1:1 for feed posts, and 16:9 for landscape YouTube. Check the current platform specification before export, because safe areas differ too.