Webform conditional calculation depending on selected options count Users register for a conference via a webform. There are options for choosing a city [mandatory] and 1-4 dates [at least 1 date has to be checked]. E.g. user checks NYC + 2015-08-07 and 2015-09-01.

The price for the conference bases on the days count: if all 4 days has been checked = X USD; if 1, 2 or 3 of 4 days = Y USD/day.

Now, I have to calculate the price based on total count of checked dates and send it to the user in confirmation e-mail. How to do it?
You have to use javascript for this and multiply the price with the number of days (the number of checkboxes checked).