Find the number of days between two dates, or add days to a date. Pick your dates and get the result instantly.
Date Calculator
Count the exact number of calendar days, weeks, weekdays, and weekend days between any two dates, or add and subtract days and weeks from a starting date.
Select your dates
Count days between two dates or project a future/past date.
Your result will appear here
Enter your values above, then press Calculate Dates — or press Enter in any field.TinyExe · Date Result
Calendar duration, weekday count & target date
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Name
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Date Span
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Weeks + Days
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Workdays / Hrs
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How this was calculated
What to do next
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Leap years (366 days when divisible by 4, except century years not divisible by 400) are automatically accounted for in all calendar calculations.
Calendar constants & month lengths
Standard Gregorian calendar durations used in date math.
| Period | Exact Duration | Notes |
|---|---|---|
| Common Year | 365 days (52 weeks + 1 day) | February has 28 days. |
| Leap Year | 366 days (52 weeks + 2 days) | February has 29 days (e.g. 2024, 2028). |
| 30-Day Months | April, June, September, November | 4 months of 30 days each. |
| 31-Day Months | Jan, Mar, May, Jul, Aug, Oct, Dec | 7 months of 31 days each. |
The formula
UTC timestamp arithmetic avoids Daylight Saving Time (DST) off-by-one errors.
Days Between Dates
Each calendar date is normalized to 00:00:00 UTC so spring/autumn clock shifts never distort the day count.
Date Offset Projection
Adds or subtracts the exact number of calendar days and resolves the resulting day of the week.
Worked examples
Three everyday date calculations.
Example 1 · Span
1 Jan 2026 to 31 Dec 2026
Counting inclusive days in a non-leap year.
| Calculation | Steps |
|---|---|
| 364 nights (+1 inclusive) | 365 total calendar days. |
| 52 weeks + 1 day | 261 weekdays and 104 weekend days. |
365 Days
Example 2 · +30 Days
30 Oct 2026 + 30 Days
Calculating a 30-day invoice due date.
| Calculation | Steps |
|---|---|
| Oct has 31 days | 1 day left in October + 29 days in November. |
| = 29 Nov 2026 | Lands on Sunday, 29 Nov 2026. |
29 Nov 2026
Example 3 · +6 Weeks
1 Mar 2026 + 6 Weeks
Projecting a 6-week milestone.
| Calculation | Steps |
|---|---|
| 6 × 7 = 42 days | Add 42 calendar days to 1 March. |
| = 12 Apr 2026 | Same day of the week 6 weeks later. |
12 Apr 2026
How to use this calculator
Pick Days Between Dates or Add / Subtract Days
Use the top toggle to select your mode.
Select your calendar dates
Choose the start and end dates (or enter weeks and days to add/subtract).
Press Calculate Dates
View total days, weeks + days, and weekday vs. weekend counts.
Frequently asked questions
How many days are in a year?
A standard common year has 365 days (52 weeks and 1 day), while a leap year has 366 days (52 weeks and 2 days). The average Gregorian year is 365.2425 days.
Does this calculator account for leap years?
Yes. Every February 29 in a leap year is automatically counted in both duration and date-addition modes.