How it works
Enter the original width and height in whole pixels, then a new width. The calculator reduces the original dimensions to their simplest ratio and rounds the matching height to the nearest pixel. A 1920 × 1080 frame has a 16:9 ratio; at 1280 pixels wide it is 720 pixels high.
Example: resize a 16:9 frame
Enter 1920 for width, 1080 for height, and 1280 for the new width. The reduced ratio is 16:9 and the matching height is 720 pixels.
Resize and crop are different
Keeping the ratio avoids stretching, but it does not turn a landscape frame into a portrait frame. To fill a different shape, crop away part of the image or add space around it. Check where faces, captions, and important details land before exporting. This calculator changes no files and does not predict the export’s byte size.
Formula
Divide both original dimensions by their greatest common divisor to get the simplest integer ratio. New height = new width × original height ÷ original width, rounded to a whole pixel.
Common questions
Does this crop my picture?
No. The calculator returns dimensions; it does not open or alter a file.
Can I turn a landscape image into 9:16 without cropping?
To keep all of the picture in a different frame shape, add borders. Stretching changes proportions, and cropping removes part of the image.
Why is the result rounded?
Images need whole pixel dimensions. Rounding can create a tiny ratio difference for small or unusual dimensions.
Three shapes you may need
A 1920 × 1080 image reduces to 16:9. A 1080 × 1920 image reduces to 9:16. A 1200 × 1200 image is 1:1. The order matters: width comes first, so reversing the two values changes landscape into portrait rather than leaving the ratio unchanged.
At a width of 640 pixels, a 16:9 image needs a height of 360 pixels. A 4:3 image at the same width needs 480 pixels. These calculations help prepare consistent cards or exports, but they do not establish a platform’s current upload specification. Check the destination’s own requirements when exact dimensions matter.
Choose between crop and borders
If the source and destination have different shapes, decide which content can be removed. A crop that works for a landscape view may cut off a person’s face, a subtitle, or the object being demonstrated. Review several moments of a video, not just its opening frame.
Adding borders keeps the complete source visible but reduces how much of the destination frame it fills. Stretching may fill the frame, yet distorts proportions. The guide to portrait video from landscape footage walks through this decision, and resizing without stretching applies it to still images.
Rounding and export requirements
An exact proportional height can be fractional, while a raster image needs whole pixels. The calculator rounds the result; a small discrepancy is expected for unusual dimensions. Some encoders impose additional requirements, such as particular dimension increments. Confirm the export settings in the actual editor rather than assuming every calculated pair is accepted.
This tool does not enlarge a source, recover cropped content, or estimate its compressed byte size. Use the Video Size Calculator for a separate duration-and-bitrate estimate. For printing, use the Photo Size Calculator to relate pixels to physical size. Keeping these questions separate makes the result easier to interpret.
