Quick answer
The calendar difference counts whole months, then remaining days. From 15 January 2024 to 10 March 2024 is 1 whole month and 24 days (55 days in total).
Enter a start and an end date. The calculator returns months and days, whole months and the total days. Use this months between dates calculator to check your own figures.
Related tools: Days Between Dates Calculator: Number of days, weeks and months between two dates. Weeks Between Dates Calculator: Time between two dates in weeks. Years Between Dates Calculator: Time between two dates in years.
How to use the Months Between Dates Calculator
- Pick start date.
- Pick end date.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Start date | A calendar date | — |
| End date | A calendar date | — |
Formula and method
Formula
calendar difference in whole years, months and days
Exact integer arithmetic.
The order of the dates does not matter. Months and years are counted on the calendar; days are exact.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Start date = 2024-01-15; End date = 2024-03-10.
| Result | Value |
|---|---|
| Months and days | 1 month, 24 days |
| Whole months | 1 |
| Total days | 55 |
Example 2
Inputs: Start date = 2023-01-31; End date = 2024-01-31.
| Result | Value |
|---|---|
| Months and days | 12 months |
| Whole months | 12 |
| Total days | 365 |
The first line is the headline result (months and days). Below it the months Between Dates Calculator lists whole months and total days, which describe the same case from other angles. Exact integer arithmetic.
How the months are counted
15 January to 15 February is one month; from 15 February to 10 March 2024 is 24 days because February 2024 has 29 days (14 + 10 = 24). The total of 31 + 24 = 55 days confirms it.
Months are not equal
Months have 28 to 31 days, so months between dates is not days divided by 30. For billing and contracts check how your agreement counts a month. Identical dates give 0.
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Start date: entering "x" shows "Start date must be a valid date." beside that field and no result.
Choosing between the Months Between Dates Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Days Between Dates Calculator](/date-calendar/days-between-dates-calculator/) | start date, end date and count end date? | Days between |
| [Weeks Between Dates Calculator](/date-calendar/weeks-between-dates-calculator/) | start date and end date | Weeks and days |
| [Years Between Dates Calculator](/date-calendar/years-between-dates/) | start date and end date | Years, months and days |
| [Date Calculator](/date-calendar/date-calculator/) | start date and operation | Resulting date |
| [Days Until Calculator](/date-calendar/days-until-calculator/) | target date | Days until |
Background: dates and times
Date and time results depend on the conventions a tool uses: whether the end date counts, whether weekends and holidays are skipped, how months of different lengths are handled and whether time zones are applied. This page states its convention, and the worked examples show it.
Dates use the Gregorian calendar and calendar days unless the page says otherwise; check deadlines against the rule in your contract or regulation.
Assumptions and limitations
- Identical dates give 0
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for start date to confirm this.
Frequently asked questions
How many weeks is that?
55 days is 7 weeks and 6 days.
Can the end date be earlier?
Order does not matter; the calculator finds the earlier date.
Is the end day counted?
The difference excludes the start day.
What does the Months Between Dates Calculator calculate?
Time between two dates in months. It returns Months and days, Whole months and Total days.
What formula does the Months Between Dates Calculator use?
calendar difference in whole years, months and days. The order of the dates does not matter.
What do I need to enter in the months Between Dates Calculator?
You enter Start date and End date.
How is the result rounded or limited?
Exact integer arithmetic. Identical dates give 0.
What is an example of a months Between Dates result?
With start date 2024-01-15 and end date 2024-03-10, the months and days is 1 month, 24 days.
Related calculators
- Days Between Dates Calculator — Number of days, weeks and months between two dates.
- Weeks Between Dates Calculator — Time between two dates in weeks.
- Years Between Dates Calculator — Time between two dates in years.
- Date Calculator — Add or subtract days, weeks, months or years from a date.
- Days Until Calculator — Days remaining until any date (generalizes “days until June 15”, “days until Christmas” and similar pages).
- Graduation Year Calculator — Expected graduation year from the start year and program length.
Sources
- ISO 8601-1: Date and time, representations for information interchange (calendar dates, ordinal dates and week dates)
- Gregorian calendar reform, papal bull Inter gravissimas (1582): the leap-year rule used for all dates
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.