How many days since a date?
Pick a past date and see how many days have passed since it. The count runs up to today unless you pick another end date.
- Days since
- 100
100 days since June 22, 2026.
- In weeks
- 14 weeks, 2 days
- In years, months, and days
- 3 months, 8 days
- Day number
- 101
- Start date was a
- Monday
Answer for the example date Wednesday, September 30, 2026. It changes to today's date when the page loads.
Days since: 100. 100 days since June 22, 2026.
Where are the dates on the calendar?
How to calculate
Counts the calendar days from a past date up to today or another end date, also as weeks and days, as years, months, and days, and as a day number.
Example with the default inputs (Start date June 22, 2026, Count up to September 30, 2026) on the example date Wednesday, September 30, 2026: 100 days since June 22, 2026.
Method: days since = end date − start date, in whole calendar days (the start date is not counted, the end date is)
- Dates are whole calendar days in the Gregorian calendar, with no time of day, so daylight-saving changes cannot add or lose a day.
- The count is the end date minus the start date: from yesterday to today is 1 day, and the same date twice is 0 days.
- The end date is today unless you change it; the page reads today’s date from your device when it loads.
- A start date after the end date has no answer.
Worked examples
Each example is checked against the calculator on every build.
- Start date 2026-01-01, Count up to 2026-09-30 gives Days since 272, In weeks 38 weeks, 6 days, In years, months, and days 8 months, 29 days, Day number 273, Start date was a Thursday.Source: Julian Day numbers (Meeus, Astronomical Algorithms, 1991, chapter 7): JD 2461313.5 − JD 2461041.5 = 272
- Start date 2024-02-28, Count up to 2024-03-01 gives Days since 2, Day number 3, Start date was a Wednesday.Source: Gregorian leap-year rule (ISO 8601)
- Start date 2000-01-01, Count up to 2026-09-30 gives Days since 9,769, In years, months, and days 26 years, 8 months, 29 days, Start date was a Saturday.Source: Julian Day numbers (Meeus, Astronomical Algorithms, 1991, chapter 7): JD 2461313.5 − JD 2451544.5 = 9769
- Start date 2026-09-30, Count up to 2026-09-30 gives Days since 0, In weeks 0 days, Day number 1.
How it works
Dates are whole calendar days in the Gregorian calendar, with no time of day, so a daylight-saving change cannot add or lose a day. Dates from January 1, 1600 to December 31, 2400 are accepted.
- Days since = end date − start date, in whole days. The start date is not counted and the end date is: from yesterday to today is 1 day, and the same date twice is 0 days.
- In weeks = the days as whole weeks and the days left: weeks = days ÷ 7 rounded down, days left = days − 7 × weeks.
- In years, months, and days: from the start date, the most whole years Y such that the start date plus Y years is not after the end date; then the most whole months M such that the start date plus Y years and M months is not after the end date; then the days left up to the end date. A day that a month does not have moves to that month’s last day (January 31 plus 1 month is February 28, or February 29 in a leap year).
- Day number = days since + 1: the end date’s number when the start date is day 1.
- Start date was a: the day of the week of the start date.
The end date starts as today. The page was built on one day and may be opened on another: the built page shows the count for its build day, and your browser replaces it with the count for your today as soon as the page loads.
When the start date is after the end date, there is no answer.
Worked examples by hand
January 1, 2026 to September 30, 2026. From January 1 to January 31 is 30 days. February to August add 28 + 31 + 30 + 31 + 30 + 31 + 31 = 212 days, and August 31 to September 30 adds 30. So 30 + 212 + 30 = 272 days. In weeks: 272 = 38 × 7 + 6, so 38 weeks and 6 days. January 1 plus 8 months is September 1, and 29 more days is September 30, so 8 months and 29 days. September 30 is day 273. January 1, 2026 was a Thursday.
February 28 to March 1, 2024. 2024 is a leap year, so February 29 comes between: 2 days, and March 1 is day 3.
January 1, 2000 to September 30, 2026. The Julian Days are 2,451,544.5 and 2,461,313.5, so the count is 9,769 days. January 1, 2000 plus 26 years is January 1, 2026, plus 8 months is September 1, 2026, plus 29 days is September 30: 26 years, 8 months, and 29 days.
The same date twice is 0 days, and it is day 1.
Other questions people ask
How do I count the days since a date?
Subtract the start date from today, in whole calendar days. From January 1, 2026 to September 30, 2026 is 272 days: 30 days to January 31, then 212 days for February to August (28 + 31 + 30 + 31 + 30 + 31 + 31), then 30 days for September.
Does the count include the start date?
No. The count is the days that have passed, so from yesterday to today is 1 day and from today to today is 0 days. If you number the days with the start date as day 1, today is the day number shown, which is the count plus 1.
Are leap years counted?
Yes. The calculator uses the Gregorian calendar, so February has 29 days in years divisible by 4, except century years not divisible by 400. From February 28 to March 1, 2024 is 2 days.
Why does the answer change when I open the page on another day?
The end date starts as today, read from your device when the page loads. The page itself was built on an earlier day, so it shows that day’s count until your browser works out today’s. Pick an end date if you want a fixed count.
Can I count days since a date in the future?
No. If the start date is after the end date there is no answer. To count the days to a coming date, use a days until or days between dates calculator.
How is the count shown in years, months, and days?
From the start date, the calculator takes the most whole years, then the most whole months, then the days left. From January 1, 2000 to September 30, 2026 is 26 years, 8 months, and 29 days.