How to use the days between dates calculator
- 1
Choose a start date
Tap the first field and pick a date. It starts on today, so for “days until” questions you only need to change the end date.
- 2
Choose an end date
Pick the second date. It can be before or after the first one; the calculator always shows the gap as a positive number.
- 3
Read the result
The total appears instantly, with the same span in years, months and days, full weeks, weekdays, weekend days, hours and minutes.
How to calculate the days between two dates by hand
The simplest manual method is to count the days left in the start month, add the full months in between, then add the days into the final month. It works well for short spans in the same year.
Full months: April 30 + May 31 + June 30 + July 31 = 122
Days into August: 2
Total: 16 + 122 + 2 = 140 days
A faster method for any two dates in the same year is to use day-of-year numbers. August 2 is day 214 of 2026 and March 15 is day 74, so the gap is 214 − 74 = 140 days. For dates in different years, add 365 for each full year in between, plus one extra day for every February 29 you pass.
Days in each month
Most mistakes in manual counting come from month lengths. Here is the full list:
| Month | Days | Note |
|---|---|---|
| January | 31 | |
| February | 28 or 29 | 29 in leap years |
| March | 31 | |
| April | 30 | |
| May | 31 | |
| June | 30 | |
| July | 31 | |
| August | 31 | July and August are the only back-to-back 31-day months |
| September | 30 | |
| October | 31 | |
| November | 30 | |
| December | 31 |
An easy way to remember them is the knuckle trick: make two fists and count months across your knuckles and the gaps between them. Every month that lands on a knuckle has 31 days.
Should you include the end date?
It depends on what you're counting. A gap or duration, like the time between two appointments or nights in a hotel, excludes the end date. A list of days that something happens on, like the days of a conference or a course of medication, includes both ends.
| Example | End date excluded | End date included |
|---|---|---|
| Monday to Friday, same week | 4 days | 5 days |
| January 1 to January 31 | 30 days | 31 days |
| January 1 to December 31 | 364 days | 365 days |
Days between popular dates in 2027
| Span | Dates | Days | Weeks | Weekdays |
|---|---|---|---|---|
| Whole year | Jan 1, 2027 → Jan 1, 2028 | 365 | 52w 1d | 261 |
| New Year → Valentine's Day | Jan 1, 2027 → Feb 14, 2027 | 44 | 6w 2d | 31 |
| New Year → Easter | Jan 1, 2027 → Mar 28, 2027 | 86 | 12w 2d | 61 |
| New Year → July 4th | Jan 1, 2027 → Jul 4, 2027 | 184 | 26w 2d | 131 |
| Memorial Day → Labor Day | May 31, 2027 → Sep 6, 2027 | 98 | 14w 0d | 70 |
| Halloween → Christmas | Oct 31, 2027 → Dec 25, 2027 | 55 | 7w 6d | 40 |
| Thanksgiving → Christmas | Nov 25, 2027 → Dec 25, 2027 | 30 | 4w 2d | 22 |
What people use it for
Personal milestones
How long you've been together, days since you moved, or how many days until a wedding, birth or graduation.
Work and contracts
Notice periods, probation, project timelines, invoice terms and the length of a fixed-term contract.
Travel and visas
Trip lengths, how long you've stayed in a country, and checking visa limits such as 90 days within 180.
Health and habits
Sobriety streaks, fitness challenges, days since a vaccination or how long a course of treatment lasts.
Leap years and why they matter
A leap year adds February 29 to keep the calendar in line with the Earth's orbit. The rule is that years divisible by 4 are leap years, except century years, which must also be divisible by 400. That's why 2000 was a leap year but 1900 was not. Any span that crosses February 29 gets one extra day.
Upcoming leap years: 2024, 2028, 2032, 2036, 2040, 2044.
Converting a day count into weeks, months and years
Weeks are easy because every week has exactly 7 days. Months and years are harder because their length changes. The calculator handles this by counting real calendar months, but for a quick mental estimate you can use the averages below. They're based on the Gregorian calendar's average year of 365.2425 days.
| Days | Weeks | Months (avg.) | Years (avg.) |
|---|---|---|---|
| 7 | 1w 0d | 0.2 | 0.02 |
| 14 | 2w 0d | 0.5 | 0.04 |
| 30 | 4w 2d | 1.0 | 0.08 |
| 60 | 8w 4d | 2.0 | 0.16 |
| 90 | 12w 6d | 3.0 | 0.25 |
| 100 | 14w 2d | 3.3 | 0.27 |
| 180 | 25w 5d | 5.9 | 0.49 |
| 365 | 52w 1d | 12.0 | 1.00 |
| 500 | 71w 3d | 16.4 | 1.37 |
| 1,000 | 142w 6d | 32.9 | 2.74 |
| 5,000 | 714w 2d | 164.3 | 13.69 |
| 10,000 | 1428w 4d | 328.5 | 27.38 |
A useful rule of thumb: 100 days is a little over 3 months, 1,000 days is about 2 years and 9 months, and 10,000 days is about 27 years and 4 months.
Days left in 2027 from the start of each month
How many days remain until New Year's Day 2028, counted from the 1st of each month:
| From | Days left in the year | Weeks left |
|---|---|---|
| Jan 1, 2027 | 365 | 52w 1d |
| Feb 1, 2027 | 334 | 47w 5d |
| Mar 1, 2027 | 306 | 43w 5d |
| Apr 1, 2027 | 275 | 39w 2d |
| May 1, 2027 | 245 | 35w 0d |
| Jun 1, 2027 | 214 | 30w 4d |
| Jul 1, 2027 | 184 | 26w 2d |
| Aug 1, 2027 | 153 | 21w 6d |
| Sep 1, 2027 | 122 | 17w 3d |
| Oct 1, 2027 | 92 | 13w 1d |
| Nov 1, 2027 | 61 | 8w 5d |
| Dec 1, 2027 | 31 | 4w 3d |
Common mistakes when counting days
- Counting both ends by accident. Counting on your fingers from the 1st to the 10th gives 10, but only 9 days have passed. Decide up front whether you need the gap or the number of days involved.
- Assuming every month has 30 days. Over a long span, the error adds up fast. Six “30-day months” are 180 days, but six real months can be anywhere from 181 to 184.
- Forgetting February 29. Any span that crosses the end of February in a leap year needs one extra day.
- Mixing up calendar days and business days. “Within 10 days” and “within 10 business days” can be a week apart. Check which one a contract or letter uses.
- Reading dates in the wrong format. 03/04 is March 4 in the US but April 3 in the UK, Canada and Australia. The calculator's date picker follows your device's format, so it avoids this.
Counting days in Excel and Google Sheets
Spreadsheets store dates as numbers, so subtracting one date from another gives the days between them. If your start date is in A1 and your end date is in B1:
| What you want | Formula | Works in |
|---|---|---|
| Days between two dates | =B1-A1 | Excel, Google Sheets |
| Days between (named function) | =DAYS(B1, A1) | Excel, Google Sheets |
| Days since a date until today | =TODAY()-A1 | Excel, Google Sheets |
| Weekdays between two dates | =NETWORKDAYS(A1, B1) | Excel, Google Sheets |
| Full months between | =DATEDIF(A1, B1, "m") | Excel, Google Sheets |
| Full years between | =DATEDIF(A1, B1, "y") | Excel, Google Sheets |
Note that NETWORKDAYS counts both the start and end date, while plain subtraction counts neither end, so the two can differ by one. Format the result cell as a number, not a date, or you'll see something like “Jan 9, 1900” instead of 9.
Time zones and daylight saving time
This calculator counts calendar days, so the answer is the same wherever you are in the world. Time zones only matter if you're counting hours. A day that includes a daylight saving change has 23 or 25 hours, which is why the hours figure in the results is based on 24-hour days. For a countdown to an exact time, use the Countdown Timer, which runs on your local clock.
A short history of the calendar we count with
The calendar used in the US, UK, Canada and Australia is the Gregorian calendar, introduced by Pope Gregory XIII in 1582 to fix a drift in the older Julian calendar, which had a leap year every four years without exception. Catholic countries switched first. Britain and its American colonies didn't switch until 1752, when Wednesday, September 2 was followed directly by Thursday, September 14, skipping 11 days.
Like most date tools, this calculator uses the Gregorian calendar for all dates, including ones before it was adopted. For dates before 1752 in a British or American historical record, the original date may have been written in the Julian calendar.
Popular lookups
Need a date rather than a count? The Date Calculator adds or subtracts days from any date, and the Days Since Calculator counts up from a past date to today.