Free aspect ratio calculator. Enter width and height to get the simplified ratio, decimal value, and the matching height for any new width.
Your results will appear here.
Enter your values and press Calculate.
The aspect ratio is the width divided by the height, simplified by their greatest common divisor (GCD). For 1920x1080 the GCD is 120, so 1920/120 : 1080/120 = 16:9. To resize without distortion, multiply the new width by the original height-over-width: a 16:9 image fitted to 1280 wide becomes 1280 × 1080/1920 = 720 tall.
An aspect ratio compares width to height as width:height. The raw pair 1920:1080 is correct but unwieldy, so we divide both sides by their greatest common divisor. GCD(1920, 1080) = 120, giving 16:9.
The decimal form is just width divided by height: 1920/1080 = 1.778. Decimals are handy for quick identity checks: 1.778 means 16:9, 1.333 means 4:3, 1.000 means square. If your decimal does not match a clean ratio, the dimensions are not an exact standard ratio.
Enter the width and height in pixels. The calculator returns the simplified ratio, the decimal value, and a common name when it matches a standard ratio like 16:9 or 9:16.
To solve for a missing side, enter the width you want to fit: the matching height is computed to preserve the ratio exactly. Want a 16:9 image at 1280 wide? The matching height is 720.
Use this page as your aspect ratio finder for any picture: enter the dimensions of the image to find its ratio, then use the fit-to-width field to find the missing height for any new size. Scaling both sides equally is how you maintain aspect ratio and resize an image without stretching or squashing it.
16:9 is the widescreen standard: YouTube, TVs, and most monitors. 9:16 is its vertical twin for TikTok, Reels, and Shorts. 1:1 is the square Instagram grid format, while 4:5 is Instagram's taller portrait post. 4:3 is classic TV and many tablets. 3:2 is the DSLR photo standard. 21:9 is the ultrawide monitor and cinematic format.
Pick the ratio your destination expects before you export: uploading 16:9 video to a 9:16 slot forces a crop or ugly letterboxing.
YouTube: 16:9 for standard video (1920x1080 or 3840x2160). TikTok, Reels, and Shorts: 9:16 vertical (1080x1920). Instagram grid: 1:1 (1080x1080); Instagram portrait posts: 4:5 (1080x1350). Thumbnails: 16:9 at 1280x720.
Shooting vertical video? Frame for 9:16 from the start. Cropping a 16:9 shot down to 9:16 throws away most of your pixels.
Resizing scales both dimensions by the same factor, so nothing distorts and nothing is lost: 1920x1080 at half size is 960x540. Cropping cuts pixels off the edges to force a new ratio, which changes the composition.
The safe resize rule: new height = new width × (old height / old width). Round to even numbers for video: many codecs require even pixel dimensions, so 719 becomes 720.
A common laptop screen is 1366x768. GCD(1366, 768) = 2, so the simplified ratio is 683:384, and the decimal is 1366/768 = 1.779. That is not exactly 16:9 (1.778), which surprises people: 1366x768 is close to 16:9 but not mathematically exact.
Fitting it to 1280 wide: new height = 1280 × 768/1366 = 719.6, rounded to 720.
The proportional relationship between an image's width and height, written as width:height. 16:9 means 16 units wide for every 9 units tall, whatever the actual pixel size.
Divide both the width and height by their greatest common divisor. For 1920x1080 the GCD is 120, so the ratio is 16:9.
16:9. GCD(1920, 1080) = 120, and 1920/120 : 1080/120 = 16:9. Its decimal value is 1.778.
Yes, exactly. It is the reference 16:9 resolution, also called Full HD or 1080p.
Scale both dimensions by the same factor: new height = new width × (old height / old width). Use this calculator's fit-to-width field to get the exact matching height.
16:9, at 1920x1080 or 3840x2160. YouTube Shorts use 9:16 vertical instead.
9:16 vertical, ideally 1080x1920. It fills the phone screen with no bars.
16:10 is slightly taller: 1.600 decimal vs 1.778 for 16:9. It is common on productivity laptops and gives extra vertical space for documents.
Because it is not exactly 16:9: GCD(1366, 768) = 2 gives 683:384, decimal 1.779. It is a rounded manufacturing resolution close to, but not exactly, 16:9.
Pick a width, then height = width × (ratio height / ratio width). For 16:9 at 1280 wide: 1280 × 9/16 = 720, so 1280x720.
Master the exposure triangle: find the right aperture, shutter speed and ISO for any scene.
Predict exactly what stays sharp in your photo with hyperfocal distance and depth of field.
Estimate video file size from bitrate and duration before you export.