[FFmpeg-user] let ffmpeg auto-calc height value when specifying (new) width while keeping aspect ratio?

[Ben]

Assume I want to re-encode a video.

The new video should have the same aspect ratio as the original.

I want to change the resolution of the new video to 1680 but don't want to calculate manually the corresponding height (dividable by 2).

Can I tell ffmpeg to automatically calculate the appropriate height by using the specified width and the given aspect ratio?

Thank you
Ben