Day Counter
Use this counter to find the number of days between two dates, including working days, weekends, and holidays.
Holiday Settings
✖Check or define holidays below
Custom Holidays:
| Name | Month | Day |
|---|
Count Days from a Date
The day counter or days calculator can be used in situations such as counting down to a birthday, tracking pregnancy days, or calculating business days left for a project.
How to use the day counter
Select a starting month, date, and year using the dropdown menus. Check the "include end day" option if needed.
Example: If a project is due at 11:59 PM on April 24 and today is March 29, select those dates and include the end day. Alternatively, select April 25 without checking the box for the same result.
Use the Settings option to include holidays. You can choose US holidays or add custom ones. The calculator will display total days, weekdays, weekends, and holidays.
The calculator assumes a Monday–Friday workweek and counts the start date fully. The end date is counted only if selected.
Counting days from a date
Enter a start date and number of days to add or subtract. Use the "business days only" option to exclude weekends.
Example: If Monday is selected and 7 business days are added, the result will be Wednesday (next week), not Monday.
Day of the week
The calculator also determines the day of the week. One popular method is the Doomsday Rule, created by John Conway.
Doomsdays
Doomsdays are specific dates that fall on the same weekday each year.
Doomsdays by month
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/3* | 2/28* | 3/14 | 4/4 | 5/9 | 6/6 | 7/11 | 8/8 | 9/5 | 10/10 | 11/7 | 12/12 |
*Leap year: Jan → 1/4, Feb → 2/29
Even months follow patterns (4/4, 6/6, etc.). March = 3/14 (π). Mnemonic: "I work from 9 to 5 at 7-11".
Anchor day
| 1900 | 2000 | 2100 | 2200 |
|---|---|---|---|
| Wednesday | Tuesday | Sunday | Friday |
Day numbers
| Sun | Mon | Tue | Wed | Thu | Fri | Sat |
|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 | 6 |
The Doomsday Rule
- Find anchor day → a
- Divide last 2 digits by 12 → b
- Remainder → c
- Divide c by 4 → d
- a + b + c + d = e
- Reduce e mod 7 → f (doomsday)
- Find nearest doomsday date
- Count difference to get final day
Example
What day was 3/15/2292? a = 5 (Friday) b = 7 c = 8 d = 2 e = 22 → 1 (Monday) Closest doomsday: 3/14 +1 day → Tuesday Answer: Tuesday