aspectCalc

Select one of the default aspect ratios or enter one yourself.
Choose which value you want to calculate by selecting the radio button next to the field. :)

the width of your ratio (e.g. 16)

the height of your ratio (e.g. 9)

the width of your media (e.g. 3840)

the height of your media (e.g. 2160)

16:9