Calculating your age in days is a fairly simple calculation of multiplying your age by the days in a year and adding the days since your last birthday. Make an adjustment for leap years.
- Determine your age and leap years
Calculate your age in years. If unsure, subtract your birth year from the current year if your birthday has occurred in the current year. Use a calendar to determine how many leap years there have been since your birth.
- Calculate days from whole years
Multiply your age in whole years by the number of days in a full year, 365.
- Calculate number of days since birthday and add leap days
Add the total number of leap days (one per leap year) and the days for each month since your last birthday. This total is your age in days.