Date Difference Calculator
This days between two dates calculator shows the gap in years, months, weeks and days for any two dates, past or future.
Quick answer: To find the number of days between two dates, subtract the earlier date from the later one. From 15 January to 3 October 2026 there are 261 days, which is 37 weeks and 2 days, or 8 months and 18 days. The calculator also shows the gap in hours and works for past and future dates.
How do you use the Date Difference Calculator?
- Enter the start date. Pick the first date in the start field.
- Enter the end date. Pick the second date; it can be in the past or the future.
- Read the gap. See the difference as years, months, weeks, days, hours and minutes.
What is the formula, and what does a worked example look like?
Formula: Days = end date − start date. Months are whole calendar months from the start date; leftover days are counted after them.
Example: 31 January 2024 to 1 March 2024 = 30 days, or 1 month and 1 day (4 weeks and 2 days).
Method & source: Gregorian calendar arithmetic; the same month rule used by the age calculator. See how we test our calculators.
Next step: try exact age on a specific date or working days between two dates.
Worked examples for the Date Difference Calculator
Each figure below was produced by the same code as the calculator, so you can enter the inputs and get the same result. Rates and thresholds are the ones on the official pages linked under “How it is calculated”.
The 2026/27 tax year: 6 April 2026 to 5 April 2027
GOV.UK gives the tax year dates; the end date is not counted by default.
- Days between the dates: 364.
- Calendar breakdown: 0 years, 11 months, 30 days.
- Counting both the first and last day gives 365 days, which is the full 365-day year.
Result: 364 days (52 weeks and 0 days) if the end date is excluded.
Independence Day to Christmas: 4 July to 25 December 2026
Used to count down to a deadline or a holiday.
- Total days: 174.
- Weeks and days: 24 weeks and 6 days.
- Calendar breakdown: 5 months and 21 days.
Result: 174 days apart.
A month-end trap: 31 January to 1 March 2027
February 2027 has 28 days, so month arithmetic needs a rule.
- Total days: 29.
- Calendar breakdown: 1 month and 1 day, because 31 January plus one month is clamped to 28 February.
Result: 29 days, shown as 1 month and 1 day.
How is the Date Difference Calculator calculated, and where do the rates come from?
The difference in days is the end date minus the start date, counted on the calendar with no time of day, so daylight saving changes never add or remove a day. The calendar breakdown adds whole months to the start date first (clamping to the last day of a short month), then counts the leftover days. The week figure is the total days divided by seven with the remainder shown.
By default the start date counts but the end date does not, the way most deadlines and notice periods are counted: 6 to 8 April is two days. Switch to inclusive counting when both the first and last day matter, such as a hotel stay measured in days or a leave request.
The tax year dates in the first example come from GOV.UK. Public holidays are not removed here; use the business days calculator when weekends and holidays matter.
For contracts and notice periods, the exact counting rule is usually written into the document, so use the calculator to check your arithmetic rather than to replace the wording. The calculation uses calendar dates with no clock time, so differences across a daylight saving change or between time zones do not shift the answer by a day, but a deadline 'by midnight in New York' still depends on the time zone named in the agreement.
- GOV.UK – Income Tax rates and Personal Allowances (tax year dates) – States the 2026/27 tax year as 6 April 2026 to 5 April 2027.
What are the common mistakes and edge cases?
- Mixing inclusive and exclusive counting. If a contract says 'within 14 days of 1 March', check whether the first day counts and which day the count ends on.
- Assuming every month is 30 days. A month between 31 January and 28 February is shorter than one between 1 March and 31 March.
- Reading dates in the wrong order. 03/04/2026 is 3 April in the UK and March 4th in the US; the date picker removes the ambiguity.
- Treating the result in months as an exact length. 'One month and one day' covers 29 to 31 days depending on the month.
- Forgetting weekends and holidays when the deadline is in working days. That needs a business-day count.
More in this category: Dates & Time calculators.
How do you find the gap between two dates?
A date difference calculator tells you how much time lies between two dates. It answers the classic question “how many days between two dates?” and also expresses the gap in years, months, weeks and days.
Whether the dates are in the past, the future or one of each, the tool orders them for you and shows the elapsed time in every unit you might need.
How are the days, weeks and months counted?
Pick a start date and an end date. The calculator compares them as calendar dates, so daylight saving and time zones cannot distort the result.
- Calendar breakdown: Complete years, months and leftover days.
- Total days: The exact day count between the two dates.
- Weeks and days: For example 12 weeks and 3 days.
- Hours and minutes: The gap converted into smaller units.
- Any order: Dates entered back to front are swapped automatically.
The result is the same whichever direction you look at it, so you can use it to count up to a deadline or back from an event.
Why does measuring the gap between dates matter?
Knowing the exact gap between two dates is useful far beyond curiosity – it underpins plans, contracts and personal milestones.
- Count down to holidays, weddings, exams or product launches.
- Measure how long a project, contract or subscription has run.
- Work out notice periods, warranty windows and trial lengths.
- Track pregnancy, travel or relationship milestones.
- Check how many days remain until a deadline.
A days between two dates calculator saves you from counting on a calendar and avoids off-by-one errors around month ends and leap years.
Worked walkthrough: a project timeline
A project started on 14 January 2026 and is due on 30 September 2026. The calculator finds 259 days between the two dates, which is exactly 37 weeks. In calendar terms that is 8 months and 16 days, because 14 January plus eight months reaches 14 September and 16 more days reach 30 September. It also shows 6,216 hours and 372,960 minutes for teams that plan in smaller units. If you enter the dates in the wrong order, the tool swaps them and tells you, so you never get a negative answer by accident.
Practical tips for Date Difference calculations
- The end date is not counted as an extra day: Monday to Tuesday is 1 day. Add one yourself if your rule counts both the first and last day.
- Use the weeks-and-days result for pregnancy, project sprints and notice periods that are written in weeks.
- For working-day gaps, use the Business Days Calculator instead – it removes weekends and holidays from the count.
- Leap years are handled automatically, so a span that includes 29 February will correctly be one day longer.
- Month lengths vary, so “months and days” depends on the start date. Rely on total days if you need an exact, unambiguous measure.
Three ways to express the same gap
One gap can be stated in several forms, and each suits a different purpose. The calendar form (years, months and days) is how people talk about durations. Total days is what contracts, warranties and countdowns need. Weeks and days is the natural unit for pregnancy, sprints and notice periods.
From 30 September 2026 to 25 December 2026 there are 86 days. In calendar terms that is 2 months and 25 days, and in weeks it is 12 weeks and 2 days. The calculator shows all of them, plus hours and minutes for anyone planning in smaller units.
Counting days: is the last day included?
The difference between two dates is the number of midnights that pass, so 1 March to 10 March is 9 days. If a rule counts both the first and the last day, add one. Hotel stays, for example, are counted in nights, which matches this style of counting, while some legal periods count inclusively. Check how your rule is worded.
Date differences worked out: three examples
Each row below is what the calculator shows for the two dates. The end date is not counted as an extra day, so the totals are the number of days from one date to the other.
| From | To | Calendar breakdown | Total days | Weeks and days |
|---|---|---|---|---|
| 1 March 2026 | 10 March 2026 | 9 days | 9 | 1 week, 2 days |
| 1 February 2028 | 1 March 2028 | 1 month, 0 days | 29 | 4 weeks, 1 day |
| 1 February 2027 | 1 March 2027 | 1 month, 0 days | 28 | 4 weeks, 0 days |
| 15 January 2026 | 3 October 2026 | 8 months, 18 days | 261 | 37 weeks, 2 days |
The second and third rows are both “1 month”, but 2028 is a leap year, so February has 29 days and the total is one day longer. If a rule counts both the first and the last day, add one to the total: 1 to 10 March is then 10 days. For time on the clock rather than dates, such as the length of a shift, use the time duration calculator.
Why months and days can look odd
Months have different lengths, so the calendar breakdown follows a set rule: add whole months to the start date, using the last day of the month when the day does not exist, then count the days left. From 31 January to 28 February 2026 the answer is exactly 1 month and 0 days, although only 28 days have passed. One day later, on 1 March, it is 1 month and 1 day. Total days is always the unambiguous figure.
Leap years and long spans
Leap years are handled automatically. 1 January 2025 to 1 January 2026 is 365 days, while 1 January 2024 to 1 January 2025 is 366 days, because 2024 contains 29 February. Both are “1 year” in calendar terms, which shows why a year is not always the same number of days.
Countdowns, elapsed time and related tools
Enter today as the start for a countdown to a wedding, exam or launch, or enter a past date to see how long ago something happened. If you enter the dates in the wrong order the tool swaps them and tells you. To exclude weekends and holidays use the business days calculator, and for someone’s age on a date use the age calculator.
Worked examples: days from 9 November 2026 to dates people count down to
The table gives the gap from 9 November 2026, with the calendar breakdown the calculator shows. The first row is the Christmas Day countdown; the 5 April row is the end of the UK tax year.
| To | Days | Weeks and days | Years, months, days |
|---|---|---|---|
| Friday 25 December 2026 | 46 | 6 weeks 4 days | 0y 1m 16d |
| Friday 1 January 2027 | 53 | 7 weeks 4 days | 0y 1m 23d |
| Monday 5 April 2027 | 147 | 21 weeks 0 days | 0y 4m 27d |
| Friday 31 December 2027 | 417 | 59 weeks 4 days | 1y 1m 22d |
Edge cases: leap years and whether the end date counts
Between 28 February and 1 March there are 1 day in 2027 but 2 days in 2028, because 2028 has a 29 February. The calculator counts every real calendar day, so leap years are handled for you.
The calculator gives the difference between two dates, so 1 January to 31 January is 30 days. If you need to count both the first and the last day, such as a 31-day booking, add one: 31 days inclusive. Check which rule your contract or form uses.
Frequently Asked Questions (FAQs)
Enter the start and end date and the calculator shows the total number of days between them. The end date is not counted as an extra day – Monday to Tuesday is 1 day.
Yes. Leap days such as 29 February are counted automatically whenever they fall between your two dates. From 1 February to 1 March is 29 days in 2028, a leap year, but 28 days in 2027. Both show as 1 month in the calendar breakdown, so check the total days figure when the exact count matters, for example for a notice period or a warranty.
Months have different lengths, so the calculator adds whole calendar months to the earlier date first and then counts the remaining days. This is the same method used to work out age.
Yes. If the start date is after the end date the calculator swaps them and tells you, so you always get a positive difference.
The result shows the gap as weeks plus leftover days, along with total days, hours and minutes. Divide the total days by 7 to check it: 15 January to 3 October 2026 is 261 days, which is 37 weeks and 2 days. Weeks are handy for pregnancy dates, sprints and notice periods, where months of different lengths would be confusing.
The calendar breakdown gives full years, months and days, and Total months shows the whole months on their own. From 15 January to 3 October 2026, for example, that is 8 months and 18 days, or 261 days in total. You can read the gap in months without counting on a calendar, and the days left over are shown separately.
Enter today’s date first and the event date second. It works as a simple countdown to any date, with the total number of days left shown at the top of the result.
Enter that past date first and today’s date second. The calculator shows the days that have passed, along with weeks, months and years.
Not in the plain difference: 1 January to 31 January is 30 days. If both the start and end day count, add one, which gives 31 days.
From 9 November 2026 to Christmas Day (Friday 25 December 2026) it is 46 days, or 6 weeks and 4 days.
By default it does not, because most deadlines count from the start date to the day before the end. Choose the inclusive option when both dates count.
The calculator counts leap days automatically. From 28 February 2027 to 1 March 2028 is 367 days because 2028 has a 29 February.
Divide the total days by seven. The result shows the whole weeks and the remaining days, for example 21 weeks and 5 days.
Confirm official deadlines. Results follow the calendar rules described on this page. Contracts, court time limits and official deadlines can count days differently, so confirm any legally important date against the governing document. See our full disclaimer.
Guides that use this calculator
- How to Calculate the Days Between Two Dates (With Examples) – Subtract the earlier date from the later one: 15 January to 3 October 2026 is 261 days. Worked examples, leap years, month-end rules and weeks.