Calculating Age & Milestones
Whether you are determining eligibility for retirement, calculating a baby's exact age in weeks, or finding out how long ago a historical event occurred, precision matters.
Use our age and date difference tools to find exact durations spanning decades, automatically accounting for every leap year along the way.
Essential Calculators
Use these tools to run the numbers for this scenario.
Action Plan Checklist
- Enter the start date (Date of Birth or historical event).
- Choose whether to calculate the difference to today, or a specific past/future date.
- Review the breakdown in total years, months, and days.
Required Reading
Deep dive into the strategies behind this use case.
How to Calculate Age from a Date of Birth
Calculating age manually involves subtracting the birth year from the current year, then adjusting the result if the person's birthday hasn't happened yet this year.
Leap Years Explained: Why We Have February 29th
Discover the astronomical reasons behind leap years, how the mathematical rules work, and why skipping leap years occasionally is necessary.
Key Terminology
Understand the financial and mathematical terms involved.
Frequently Asked Questions
Does the age calculator account for leap years?
Yes. Because it uses exact calendar math, every extra day from February 29th over the lifespan is accurately counted.