That was such a long time. There is now an article that clearly describes how to do advanced calculation. Kindly check on it here and if you don’t find your solution, please type your question and example so that we can chime in on it.

Actually my question is not just about the calculation of dates. It is about the display of the calculation in Years, Months.

I have a date variable which opens up the calendar to enter date of survey.
I have another date variable which opens up the calendar to enter the date of birth.

I then calculate the age by subtracting the date of birth from the date of survey. In my data set, if the child is 15 months old, the age displayed is “15 months”. However, I want the display to be “1 year 3 months”.

Is it possible to do this on Kobo?

Please let me know if there is a solution to this.

And as indicated by @Xiphware FYI depending on how pedantic you wish to be, you might be interested in this thread (specifically discussing leap years…). But since you just want years and months here - that is, the precise number of days doesn’t matter - the impact of leap years will be nominal.
Regards
Stephane

FYI depending on how pedantic you wish to be, you might be interested in this thread (specifically discussing leap years…). But since you just want years and months here - that is, the precise number of days doesn’t matter - the impact of leap years will be nominal.

Dear @stephanealoo, about age calculation, how does one do it directly from the KoBoToobox form generation to get this kind 0f form preview as per your post. The article on Advanced Use of Calculate Questions does not seem to explain well.

Hi,
You should use the same principle used in the previous form, the only difference would be that you are adding this on the form builder as opposed to an XLS form.

You will need to create a calculate question from the form builder

You will then have to type your formula in the bar. Remember to use the reference to the previous questions that have the date of birth and date of interview. Please note that the formula will be the same as to the one you could have used in XLS

You will simply type the following into the calculate (${interviewdate}-${birth}) div 365

Unfortunately when working with FormBuilder you can not create calcuations on other types of questions such as text or integer, you must create it on calculate questions. When viewing the form, calculate questions will not be shown.

Hello @stephanealoo in your example is it possible to calculate age by using current date(Meta data) instead of interview date.

I want end user to provide me only date of birth in date format then in the backend I want to subtract date of birth from today’s date. Can you provide me the right formula for this ? many thanks!

Hello @anilgnydn,
Using today() function together with the birthday will give you the (dynamic) age of today. Which might be different of this person’s age tomorrow already (or the one of a tomorrow submitted person with the same birthday) in your backend. But NOT the age at interview.
Do you really want this?
Also be aware that metadata ${today} acts differently to today() function.