Date Difference Calculator
Count the days, weeks, months and years between two dates, or the business days between them excluding weekends and your own holidays.
Last updated: October 2026
Reading this result: from Thu 1 Jan 2026 to Thu 31 Dec 2026 is 364 days.
Uses the Gregorian calendar. Business days are Monday to Friday; public holidays are not built in — add the ones that apply to you.
How the difference between two dates is calculated
The calculator counts the calendar days from the start date to the end date, using the real length of every month and every leap year. By default it gives the difference between the dates, which does not count the end date: from 1 March to 2 March is 1 day, the same as Excel’s =B1-A1. Tick Include the end date when you need to count both the first and last day, for example the length of a holiday or a hire period.
The total is also shown as whole weeks plus days, and as years, months and days. If you enter the dates the wrong way round, they are swapped and the result says so — the calculator never shows a negative number of days without telling you.
Calendar days vs business days
Calendar days count every day. Business days count only Monday to Friday, and leave out any holidays you add. Use calendar days for ages, notice periods measured in days, interest and rental periods; use business days for delivery times, processing times and deadlines expressed in “working days”.
Inclusive or exclusive counting
Most disagreements about date ranges are about the end points, not the arithmetic. “From 1 to 10 March” is 9 days if you are measuring elapsed time and 10 days if you are counting the days on which something happens. The calculator states the convention it used under every result:
- Date difference: end date not counted unless you tick “Include the end date”.
- Business days: the end date is always counted if it is a weekday; the start date is counted unless you untick “Count the start date”.
Why months and years can be ambiguous
A day is always a day, but a month can be 28, 29, 30 or 31 days long, so “one month after 31 January” has no single answer. This calculator counts whole months from the start date’s day of the month, and when that day does not exist in a shorter month it uses the last day of that month. The remaining days are counted from there:
| Dates | Days | Years, months, days |
|---|---|---|
| 31 Jan 2026 → 28 Feb 2026 | 28 | 28 days |
| 31 Jan 2026 → 1 Mar 2026 | 29 | 1 month, 1 day |
| 15 Jan 2026 → 15 Mar 2026 | 59 | 2 months |
| 29 Feb 2024 → 28 Feb 2025 | 365 | 11 months, 30 days |
| 29 Feb 2024 → 1 Mar 2025 | 366 | 1 year, 1 day |
If a contract or policy defines months in another way, follow that definition; the total number of days is never ambiguous.
Leap years
A year has 366 days when February has 29 days: every year divisible by 4, except century years not divisible by 400 (so 2000 was a leap year and 2100 will not be). Any range that contains 29 February is one day longer than the same range in an ordinary year, and someone born on 29 February reaches a full year of age on 1 March in non-leap years under this convention.
Business days and your own holidays
Business days are counted by going through the range day by day, skipping Saturdays and Sundays. Public holidays vary by country, region and year, so none are built in. Add the holidays that apply to you: each one that falls on a weekday inside the range is excluded. A holiday on a weekend, outside the range, or entered twice is listed separately and does not change the count.
Five worked examples
Date difference
A normal range
From 15 March 2026 to 4 October 2026.
Total = 203 days = 29 weeks, 0 days
= 6 months, 19 days
The difference is 203 days. Counting both dates gives 204.
Same day
Start and end on the same date
From 1 June 2026 to 1 June 2026.
Including the end date = 1 day
Business days (Mon 1 Jun) = 1
Same-day ranges are where the convention matters most: no time has passed, but one day is covered.
Leap year
A year that contains 29 February
From 1 February 2024 to 1 February 2025, compared with 2025 to 2026.
2025→2026: 365 days
Both are exactly 1 year, but the first is a day longer because it includes 29 February 2024.
Business days
A range that spans weekends
From Friday 2 October 2026 to Friday 16 October 2026, counting both dates.
Weekend days = 4 (3–4 and 10–11 Oct)
Business days = 11
Eleven working days. Untick “Count the start date” and it becomes 10 — the working days after Friday 2 October.
Custom holidays
Excluding your own holidays
All of December 2026, counting both dates, with holidays added for Fri 25 Dec, Sat 26 Dec and Thu 31 Dec.
25 Dec (Fri) and 31 Dec (Thu) excluded = 2
26 Dec is a Saturday — no effect
Business days = 21
Only the two holidays on weekdays reduce the count; the Saturday holiday is reported but makes no difference.
Do it in a spreadsheet
With the start date in A1, the end date in B1 and a list of holidays in D1:D10:
- Days between the dates:
=B1-A1(add 1 to count both days) - Whole years, months, days:
=DATEDIF(A1,B1,"Y"),"YM"and"MD"— note that the “MD” part can give odd results around month ends, which is why the convention above matters. - Business days, both dates counted:
=NETWORKDAYS(A1,B1,D1:D10) - Business days with a different weekend:
=NETWORKDAYS.INTL(A1,B1,1,D1:D10)(the 1 means Saturday–Sunday)
Frequently asked questions
How do you calculate the number of days between two dates?
Subtract the start date from the end date. From 1 March to 31 March is 30 days, because the end date is not counted. If you want to count both the first and the last day — for example, the length of an event — add one: 31 days.
Should I include the start and end dates?
It depends on what you are measuring. Elapsed time (age, a notice period from today, interest days) normally excludes the end date. The length of something that happens on every day in the range (a holiday, a hire period, a project) normally counts both ends. Contracts often define this, so check the wording.
How are months and years counted when months have different lengths?
This calculator counts whole months from the start date’s day of the month. If the end date’s day is earlier than the start date’s, the last month is not complete. When a month is too short (31 January plus one month), the date is moved to that month’s last day. So 31 January to 28 February 2026 is 28 days, and 31 January to 1 March 2026 is 1 month 1 day.
How are leap years handled?
Every calculation uses the real calendar, so 29 February is counted in leap years (2024, 2028) and not in others. A full year from 1 March to 1 March is 366 days when it contains 29 February and 365 days otherwise.
What counts as a business day?
Monday to Friday. Saturdays and Sundays are never counted. Holidays you add are removed only if they fall on a weekday inside the range; a holiday on a weekend makes no difference because that day was not a business day anyway.
Does the calculator know my country’s public holidays?
No. Public holidays differ by country, region and year, and some are announced late, so the calculator does not guess. Add the holidays that apply to you, and it will exclude each one that falls on a weekday in your range.
Is this the same as Excel’s NETWORKDAYS function?
Yes, when “Count the start date” is ticked: both the start and end dates are counted if they are weekdays, and listed holidays are excluded. Untick it to count only the business days after the start date, which is how many deadlines are measured.
Keep going
Written and reviewed by Ghayas Uddin, MS (Finance), financial analyst. Last reviewed 4 October 2026. Found an error? Email support@babadigit.com and we will correct it.