Calculating the age gap between two people
Sibling spacing, couple gaps, generational comparisons — how to measure the difference between two birth dates accurately.
3 min readReviewed May 1, 2026
Quick answer
Subtract the older person's birth date from the younger person's — the result is the age gap in years, months, and days, and it doesn't change over time.
Worked example
Person A born 4 June 1992, person B born 17 January 1996.
1. 1. Years
1996 − 1992 = 4. June > January, so subtract one → 3 years.
2. 2. Months
From 17 January to 17 June = 5 months. So 3 years, 5 months.
3. 3. Days
From 4 June to 17 June = 13 days. Final gap: 3 years, 5 months, 13 days.