How can I create a booking form for tours with calculations?

Hi i was wandering if you could help me create a booking form for tours where i can add different value to different seasons? 

When people select their dates, there are different prices behind different seasons.

Oktober - March = 1

April = 2

May - June = 3

July - September = 4

All help would be really appreciated.

To set a different value per month, try this workaround.

1. Use Birth Date Picker field

2. Add Form Calculation and get the Date Field value into string/text format.

3. Create an Update/Calculation a Field condition like the following.

You can do the same condition for the other months.