Age Difference Calculator
Calculate the precise difference between any two birthdates or dates — in years, months, and days. Works for age gaps between people, time elapsed between events, and more.
Exact vs Approximate
An age difference in years only is an approximation. This calculator gives the exact difference down to days, accounting for leap years and varying month lengths. Two people born on the same date in different years always have an exact whole number difference in years.
Uses
Age difference between siblings, parents and children, couples, or colleagues. Time elapsed since an event — a project start date, anniversary, or historical event. Days until a future date — a deadline, holiday, or birthday.
Leap Years
A year is a leap year if divisible by 4, except for century years which must be divisible by 400. So 2000 was a leap year, but 1900 was not. Anyone born on February 29 has a 'real' birthday only every 4 years — this calculator handles these correctly.
When to Seek Medical Advice
Calculator results are estimates based on population averages and statistical formulas — they are not medical diagnoses. Consult your GP if calculator results suggest a health concern, if you have symptoms requiring attention, or if you are managing a chronic condition where precise monitoring is important. Regular health checks (annual GP review, NHS Health Check for those aged 40-74) provide professional assessment using validated clinical tools. Use health calculators to inform conversations
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