 # Date Calculation

I would like get the difference between two dates in order to enable me calculate the ages of children in months. My assumption is that their mothers (who will be asked when the child was born) may not know or their ages in month but are aware on their date of birth. So I need a formula that would substract their date of birth from the current date Now() and display the result in months.
Kindly assist

Hello @rigs,

I've done something like this in the past for some child growth monitoring systems. Try it and test to see if it solves your question

You will need a variable with DOB. We will then get the `date serial` that corresponds with it using conversion `int(\${DOB})` and we will lessen that from `int(today())` and the result (`in days`) will be devided by `30.4384064010668` -- very debatable, but that's about on average how many days they might be in a month for this calculations

Wrapping up, in the variable where you need the number of age in months, use the following in the Calculation column `(int(today()) - int(\${DOB})) div 30.438406010668` and if you need some rounding of the decimal places, use `round((int(today()) - int(\${DOB})) div 30.438406010668,2)` instead (2 dec places)

One technical tip, always make sure that tablet dates are set properly, and one quick way of being sure no off dates are used is to limit `today() >= \${date_survey_started}`

Hoping this helps,

Jules R