New Year to Christmas, 2026
From 1 January 2026 to 25 December 2026 is 358 days, which is 51 weeks and 1 day (51.14 weeks). The calendar breakdown is 0 years, 11 months and 24 days. Include the end date and the total becomes 359 days.
Date Difference Calculator
Find the exact gap between two dates as total days, weeks and months, and as a calendar breakdown of years, months and days. Choose whether to include the end date.
Choose two dates
Leave blank to use today.
Pick your dates
Choose a start date to see the gap. If you leave the end date blank, today is used.
How to use the Date Difference Calculator
- Pick a start date and an end date. If you leave the end date blank, today is used.
- Switch on Include end date if you want to count the last day as well, for example for a booking that covers both the first and the last night.
- Read the gap as total days, weeks and days, decimal weeks, whole months, an approximate decimal month figure, and a years, months and days breakdown.
- If your end date is earlier than your start date, the calculator swaps them for you and tells you it did. Press Swap dates to flip the fields yourself.
- Press Copy summary to put all the figures on your clipboard, or Reset to start again.
How the date difference is worked out
Each date is treated as a plain calendar day, not a moment in time, so your time zone and daylight saving changes cannot shift the answer. The total is the number of days you would count stepping from the start date to the end date, and it is exact.
The years, months and days breakdown is calendar-aware. It finds the largest number of whole months you can add to the start date without passing the end date, then counts the days left over. When the start day does not exist in a month (the 31st, or 29 February), the day is clamped to the last day of that month, so 31 January plus one month is the end of February.
Decimal weeks are simply days divided by 7. Decimal months are different: months have different lengths, so the decimal figure divides by the average Gregorian month of 30.436875 days (365.2425 divided by 12). Treat it as a rough size, and use the whole months or the years, months and days breakdown when you need calendar months.
Total days = end date - start date (+ 1 when the end date is included) Weeks = floor(days / 7), remaining days = days mod 7, decimal weeks = days / 7 Whole months = largest N where start date + N months is not after the end date Decimal months (approximate) = days / 30.436875
Assumptions and limits
- Dates are whole calendar days. Time of day, time zones and daylight saving changes are ignored.
- Leap years use the modern Gregorian rules for every year, including years before the calendar was adopted. Historical calendar changes are not modelled.
- Supported years are 1 to 9999.
- The decimal months figure is an approximation based on an average month length, not a count of calendar months.
- Other tools may break years, months and days down differently when the start day is the 29th, 30th or 31st. This one clamps to the end of the shorter month.
Practical examples
A longer stretch across a leap year
From 15 March 2024 to 3 November 2026 is 963 days: 137 weeks and 4 days, or 137.57 weeks. That is 2 years, 7 months and 19 days, which is 31 whole months. The approximate decimal figure is 31.64 months.
Month ends behave differently from day counts
From 31 January 2025 to 1 March 2025 is 29 days. As a calendar breakdown it is 1 month and 1 day, because 31 January plus one month lands on 28 February.
Frequently asked questions
Does the calculator count the start date and the end date?
By default it counts the days between them, so the start day is not counted and the end day is not either: 1 June to 2 June is 1 day. Turn on Include end date to count the final day as well, which adds 1.
Why is a full year not exactly 12.00 months in the decimal figure?
The decimal figure divides days by an average month length, and a 365-day year is slightly shorter than 12 average months. 1 January 2026 to 1 January 2027 shows about 11.99 months, while the calendar breakdown correctly says 1 year, 0 months and 0 days.
What happens if my end date is before my start date?
Nothing breaks. The two dates are swapped, a note tells you the range was reversed, and you see the gap between the earlier and later date. The result is a positive size, not a negative one.
Which should I use, whole months or decimal months?
Use whole months, or the years, months and days breakdown, when calendar months matter, such as contracts, ages or subscriptions. The decimal figure is only a quick approximation of size.
Can I compare dates from different years or centuries?
Yes, any dates from year 1 to year 9999 work. Leap years follow the standard Gregorian rules, applied to every year.