Converting AM/PM Time to 24-Hour Time

Hi...

What sort of calculation or work-flow would be needed to convert AM/PM time input to a 24-hour output so it can be used in further calculations as explained in https://www.jotform.com/help/443-Mastering-Date-and-Time-Calculation 

You might ask: "Why not just use 24-hour time format to start with?" ... Well, because some form users may not be adept or comfortable with 24-hour time... so I have to keep it simple by allowing them to answer in AM/PM Time format.

Thanks in advance.

P.S. if you already have a page link where this is explained, the link would be great; I've just not been able to locate one.

It seems that there is no easy way to convert the value from 12 hour format to 24 hour and may be required to have some conditions to be setup. Please allow me sometime to check in my free time on this and get back to you with relevant information.

Thank you for your patience.