Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate pixel dimensions from an aspect ratio and one known dimension.
The reverse of the Image Aspect Ratio Calculator -- given a target aspect ratio (e.g. 16:9) and one known dimension (width or height), this tool calculates the matching height to preserve that exact ratio.
Enter your aspect ratio (e.g. 16 and 9) and your known width in pixels. The matching height appears instantly.
The interface has three fields: ratio width (pre-filled with 16), ratio height (pre-filled with 9), and a known width in pixels. The tool returns the matching height in pixels. Despite the general description on this page, the current version solves for height from a known width only. It does not offer a switch to solve for width from a known height. If you have a fixed height and need the width, you can work around it (see below).
Height = known width ÷ ratio width × ratio height
The result is rounded to the nearest whole pixel for display and shown with thousands separators. All three values must be greater than zero, otherwise the tool shows a prompt to enter a ratio and known width.
For a 16:9 image with a width of 1920 pixels, the height is 1920 divided by 16, which is 120, times 9, giving 1080. For a 4:3 image at 1600 pixels wide, the height is 1600 divided by 4 times 3, which is 1200. For a 1:1 square at 1080 wide, the height is 1080. For a portrait 4:5 image at 1080 wide, the height is 1080 divided by 4 times 5, giving 1350. For a hypothetical 21:9 ultrawide banner at 2560 wide, the height is 2560 divided by 21 times 9, which is about 1097.14, shown as 1,097 pixels after rounding.
Because the tool solves only for height, use a simple trick: swap the ratio numbers and treat your known height as the width. For example, you want a 16:9 image that is 1080 pixels tall. Enter 9 as the ratio width, 16 as the ratio height, and 1080 as the known width. The result, 1920, is the width of your 16:9 image. This works because the ratio is symmetric when you flip both the sides and the role of the known value.
Use the smallest whole numbers if you can, but any positive numbers work, including decimals. A ratio entered as 1.91 and 1 gives the same result as 191 and 100. Be careful about order: width first, then height. Entering 9 and 16 for a landscape image gives a tall portrait shape. Also check the known width refers to the width of your final image, not the width of a container or screen area with a different ratio.
Remember that changing an image to a different ratio requires cropping or padding, not just resizing, otherwise the picture is distorted.
Only height from width -- this tool takes your known width and returns the matching height. To go the other way, swap the ratio (for example enter 9:16 instead of 16:9) and use your height as the "width" value.
Not directly. The tool takes a known width and returns the height. To find a width from a known height, swap the ratio numbers and enter your height in the known width field.
The height is rounded to the nearest pixel, since images cannot have fractional pixels. Choose a width that is a multiple of the ratio width for an exact result.
Yes, any positive numbers work. For example 1.91 and 1 behave like 191 and 100.
The ratio fields start at 16 and 9, so you only need to type a known width to get a 16:9 height right away.