Months calculator
Created by
Eon CalculatorThe month’s calculator is an easy-to-use tool that helps with three significant functions: finding the number of months between two dates, adding months to a given date, and subtracting months from a date. This article will explain how this month’s calculator works, the conversion formula and examples.
A month is a period of time that is roughly based on the Moon's cycle around the Earth, which takes about 29.5 days. A month usually has 30 or 31 days, except for February, which has 28 days in a regular year and 29 days in a leap year. There are 12 months in a year, starting with January and ending with December.
How the months calculator works
Between dates
To calculate the month between dates, subtract the start year and month from the later year and month. If the day of the later date hasn’t yet occurred on the earlier date, reduce the total by one month.
Months = (Later Year − Earlier Year) × 12 + (Later Month − Earlier Month) + Adjustment
For example: (2023 - 2018) × 12 + (4 - 4) = 60 months.
Adding months Adding months to a specific date function adds a specific number of months to a date, moving it forward. This calculator keeps the same day, but it adjusts automatically if the new date doesn’t exist (like January 31 turning into February 28 or 29).
New Date = Starting Date + Number of Months
For example: March 10, 2022 + 6 months = September 10, 2022.
Subtracting months
Subtracting months from a date option lets you calculate backward in time by removing a specific number of months from a date. Like adding months, the tool adjusts if the resulting date isn’t valid (e.g., March 31 becomes February 28 or 29).
New Date = Starting Date − Number of Months
For example: December 15, 2023 - 8 months = April 15, 2023.
How to use the months calculator
Step 1: Choose what you want to calculate, the month between two dates, add months, or subtract months. Each option serves a different purpose.
Step 2: Enter the start and end dates (if needed) in the format provided (DD/MM/YYYY). Make sure the dates are accurate before proceeding.
Step 3: Click the “Calculate” button after entering the details. The calculator will process the information and display the result immediately.
Step 4: If you want to perform another calculation, use the “Clear” button to remove the previous inputs. Then, enter new values and repeat the steps.
| Start Date | End Date | Total | Weekends | Workdays |
|---|---|---|---|---|
2025-01-01 | 2025-01-31 | 31 days | 10 days | 21 days |
2025-02-01 | 2025-02-28 | 28 days | 8 days | 20 days |
2025-03-01 | 2025-03-31 | 31 days | 10 days | 21 days |
2025-04-01 | 2025-04-30 | 30 days | 9 days | 21 days |
2025-05-01 | 2025-05-31 | 31 days | 10 days | 21 days |
2025-06-01 | 2025-06-30 | 30 days | 9 days | 21 days |
2025-07-01 | 2025-07-31 | 31 days | 10 days | 21 days |
2025-08-01 | 2025-08-31 | 31 days | 10 days | 21 days |
2025-09-01 | 2025-09-30 | 30 days | 9 days | 21 days |
2025-10-01 | 2025-10-31 | 31 days | 10 days | 21 days |
2025-11-01 | 2025-11-30 | 30 days | 9 days | 21 days |
2025-12-01 | 2025-12-31 | 31 days | 10 days | 21 days |
Table 1 shows 12 months data from 2025, including working days, weekends, and days of the month.
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