# Date Difference Calculator URL: https://discuvr.org/date-difference/ Last updated: 2026-11-08 MCP tool: `date_difference` Count the days, weeks, months and years between two dates, including working days, or add and subtract days and working days from a date. How many days until a deadline, how many working days a notice period covers, what date is 90 days after an invoice. Enter the dates as dd/mm/yyyy and get the answer in days, weeks, months and working days at once. ## What it does - Years, months and days between two dates, plus the total in days, weeks and hours. - Working days (Monday to Friday) and weekend days in the period. - Choose whether to count the end date, as many contracts and leave policies do. - Add or subtract calendar days or working days from any date. - Handles leap years and month ends correctly, for dates from year 1 to 9999. ## How it works 1. Enter a start and end date as dd/mm/yyyy, or press Today. 2. Tick Include the end date if both days should count. 3. Read the difference, or use the second form to add or subtract days. ## Worked example: a 30-day notice and a 90-day payment term Notice served on 15/01/2026 with 30 days to reply: add 30 days and the deadline is 14/02/2026, a Saturday, so check whether your contract moves it to the next working day. An invoice dated 31/10/2026 on 90-day terms is due on 29/01/2027. Ticking Count working days only counts Monday to Friday instead; public holidays are not skipped. ## How months are counted at month ends A month is counted from a day to the same day in the next month. When that day does not exist, the last day of the month is used, so one month from 31/01 is the end of February (28/02, or 29/02 in a leap year). That is why 31/01 to 28/02 shows as one month rather than 28 days. ## Which days the working-day count includes Without Include the end date, the count runs from the start date up to but not including the end date, so Monday 02/11/2026 to Friday 06/11/2026 gives 4 working days; tick it to get 5. When adding working days the start date itself is not counted: 1 working day after Friday 06/11/2026 is Monday 09/11/2026, and 1 working day after Saturday 07/11/2026 is that same Monday. The weekend is always Saturday and Sunday, so where it falls on a Friday, as in Saudi Arabia or Iran, adjust by hand. Years follow the month-end rule too: 29/02/2024 to 28/02/2025 shows as exactly 1 year, while 28/02/2026 to 31/03/2026 is 1 month and 3 days. ## Legal and contract deadlines: is the first day counted? Most deadline rules leave out the day of the event and count the last day, and that is how this tool adds days: 30 days from a notice received on Thursday 15/01/2026 run from 16/01 and end on 14/02/2026. In EU law, Article 3(1) of Regulation 1182/71 says the day of the event is not counted, and Article 3(4) moves a period that would end on a Saturday, Sunday or public holiday to the end of the next working day, so that deadline becomes Monday 16/02/2026; this does not apply to periods counted backwards. In India, section 9 of the General Clauses Act 1897 reads "from" as excluding the first day and "to" as including the last. The difference between two dates counts the same way unless Include the end date is ticked: 15/01/2026 to 14/02/2026 is 30 days. A contract or court rule can set its own method, so check its wording. ## Questions **How many working days are in a month?** Usually 20 to 23 Monday-to-Friday days. Enter the first and last day of the month with include end date on to get the exact number, then subtract any public holidays that apply to you. **Can I count backwards from a deadline?** Yes. Adding days accepts a negative number, so -10 with working days on counts back from a filing date to find when the documents must be ready. **Does it count public holidays?** No. Working days here means Monday to Friday. Holidays differ by country, state and employer, so subtract any that apply to you. **Should I include the end date?** From 01/01 to 02/01 is one day apart. If you are counting days of leave or a notice period where both the first and last day count, tick Include the end date to get two. **How are months counted?** A month runs to the same day number in the next month. From 31/01 it ends on the last day of February, since February has no 31st. **How do I get the same numbers in Excel or Google Sheets?** Subtracting two dates, =B1-A1, gives the day count with Include the end date (count both days) off: 15/01/2026 to 14/02/2026 is 30 in both. NETWORKDAYS(A1, B1) counts both the start and the end date, so it matches the working-day count with that box ticked: Monday 02/11/2026 to Friday 06/11/2026 gives 5. WORKDAY(A1, 10) matches adding 10 days with Count working days only (skip Saturdays and Sundays) ticked: 10 working days after Friday 06/11/2026 is Friday 20/11/2026. For a Friday and Saturday weekend, use NETWORKDAYS.INTL(A1, B1, 7). Those functions also accept a list of holiday dates as an extra argument, which this tool does not. Some language versions of Excel translate the function names and separate arguments with a semicolon. **Is the hours figure exact across a clock change?** No. Hours are the day count times 24, and times of day are not used, so a period that crosses a daylight saving change is one hour shorter or longer in real elapsed time. **What date is 90 days from today?** Use Add or subtract days: press Today, enter 90 and press Calculate. The result shows the date and its weekday, for example 01/01/2026 plus 90 days is 01/04/2026, a Wednesday. Tick Count working days only for business days instead: 30 working days from 01/01/2026 is 12/02/2026, a Thursday. Public holidays are not skipped, and -90 counts back. **Can I type dates in US month/day/year order?** No. Every date is read day first, as dd/mm/yyyy, so 03/04/2026 means 3 April 2026, not March 4. A US date such as 12/25/2026 is rejected because there is no month 25, but one where both numbers are 12 or less is accepted with the wrong meaning. Swap the first two numbers before you type: March 4, 2026 is 04/03/2026. The Today button always fills in today in the right order. ## More in Everyday Helpers - [Percentage Calculator](https://discuvr.org/percentage-calculator/) - [SIP Calculator](https://discuvr.org/sip-calculator/) - [BMI Calculator](https://discuvr.org/bmi-calculator/) - [QR Code Generator](https://discuvr.org/qr-code-generator/) ## Often used with - [Unix Timestamp Converter](https://discuvr.org/timestamp-converter/) - [Age / Date Difference Calculator](https://discuvr.org/age-calculator/) --- Part of Discuvr (https://discuvr.org/): Discuvr is a collection of free, focused tools for day-to-day professional work - office and data utilities, legal and compliance helpers, privacy and security checks, and developer formatters. 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