How do I count months between two dates?

Step forward one calendar month at a time from the start date until you'd pass the end date, counting each full month; the leftover is the remaining days. From 2020-01-15 to 2023-07-20 that's 42 full months and 5 days, which is 3 years 6 months and 5 days.

Why not just divide the days by 30?

Because months have 28 to 31 days, dividing total days by 30 only approximates the answer. This calculator counts real calendar months, so 2024-01-01 to 2024-12-31 is 11 months and 30 days — not 12 — even though it's almost a full year.

How does it handle end-of-month dates?

Each step clamps the day to the length of the target month. So one month after January 31 lands on February 28 or 29, and 2020-01-31 to 2020-03-01 comes out as 1 month and 1 day (30 days total), which matches how people count calendar months.

What if I enter the dates backwards?

The calculator swaps them automatically, so the result is always a positive duration. The order you type them in doesn't change the number of months, years, days or weeks reported.

Is this the same as age in months?

Yes — enter a birth date as the start and today (or any date) as the end to get age in months. It's commonly used for a baby's age, lease and loan terms, project durations and subscription periods, anywhere whole calendar months matter.

Months Between Dates Calculator

From → To	Months
2024-02-29 → 2024-03-29	1 mo
2020-01-31 → 2020-03-01	1 mo 1 day
2024-01-01 → 2024-12-31	11 mo 30 days

This calculator counts the full calendar months between two dates by stepping forward one month at a time — clamping the day to each month's length so end-of-month dates behave — then reporting the leftover days. It also breaks the total into years and months and gives the total days and weeks.

Reviewed: June 20, 2026 · Author: Naveen P N, Founder — AI Calculator · Verified against: forward calendar-month counting, recomputed in code.

How it counts

Full months

step +1 calendar month from start until passing end

Breakdown

years = months ÷ 12 · leftover = days past the last whole month

Calendar months vary from 28 to 31 days, so the only reliable way to count them is to advance month by month. At each step the day is clamped to the target month's length, so one month after Jan 31 lands on Feb 28 or 29. Whatever time is left after the last whole month is reported as days; the total days and weeks come straight from the day difference.

Worked examples

2020-01-15 to 2023-07-20:

Step & leftover

42 full months + 5 days = 3 yr 6 mo 5 days · 1282 days

2020-01-31 to 2020-03-01 (end-of-month):

Clamped

Jan 31 → Feb 29 (1 month) + 1 day · 30 days

2024-01-01 to 2024-12-31:

Almost a year

11 months + 30 days · 365 days

So a span of 1282 days is 42 months, the tricky Jan-31 case is 1 month and 1 day, and a near-full year reads as 11 months and 30 days — not 12 — because Dec 31 hasn't reached Jan 1.

Related date & time calculators

Date Difference Calculator — full breakdown.
Weeks Between Dates — in weeks.
Age Calculator — years, months, days.
Business Days — weekday count.
All Date & Time Calculators — the full collection.

Frequently Asked Questions

How do I count months between dates?⌄

Step forward a month at a time, count full months, report leftover days. 2020-01-15 → 2023-07-20 = 42 mo 5 days.

Why not divide days by 30?⌄

Months are 28–31 days. 2024-01-01 → 2024-12-31 is 11 mo 30 days, not 12, even at 365 days.

End-of-month dates?⌄

The day is clamped per month. Jan 31 → Mar 1 = 1 mo 1 day (30 days total).

Dates entered backwards?⌄

Swapped automatically; the result is always positive.

Same as age in months?⌄

Yes — use birth date and today. Also for leases, loans, projects and subscriptions.

Months Between Dates Calculator

Months between dates — Quick answer