Months Since Birth
Months lived = (Years × 12) + Extra monthsYears × 12 + remaining months this year
Free online tool
Months Since Birth
Enter your birth date to see your age expressed in total months.
Instant calculation
Calculate Months Since Birth
Enter your birth date to see your age in months.
Your result
Calculation
Your numbers stay in this browser. Nothing is uploaded or saved.
Three clear steps
How to use this calculator
- 01
Enter your birth date
Type your birth year, month and day.
- 02
Calculate total months
Select Count Months to see your age in months.
- 03
Read the extra days
The result also shows any additional days beyond full months.
The formula
How this calculation works
Convert years to months (multiply by 12), add the remaining months, and show any extra days.
Check the method
Worked examples
Each example follows the same formula used by the calculator.
Born Jan 15, 1990 — months lived?
Years × 12 + remaining months this yearSee result — it updates for today's dateBorn 1 month ago — result?
1 month and a few extra days1 month, X daysCommon questions
Questions about this calculation
Why count months instead of years?
Counting months is useful for baby development tracking, medical timelines and short-term milestones where years would be too coarse.
How are months calculated?
Total months = (Years times 12) + remaining months. Extra days beyond full months are shown separately.
Do different month lengths affect the calculation?
The month count uses calendar months, not 30-day periods. Starting from your birth day, each month refers to the same day of the next calendar month.
What are the extra days in the result?
After counting all complete months, remaining days that do not make a full month are shown as extra days.
How do I track my baby's age in months?
Enter the birth date. The Months Since Birth calculator shows the exact number of full months and extra days.
Continue calculating