Time Between Dates Calculator: Days, Weeks, Months & Years
Enter a start date and end date to instantly see the exact duration between them in every unit - years, months, weeks, days, hours, minutes and seconds. Toggle working-days mode to count only Monday-Friday, include or exclude the end date, and follow the step-by-step calculation panel to see exactly how the answer is built.
How the time between dates is calculated
The core calculation is straightforward: subtract the start date from the end date to get a count of elapsed days. Every other unit follows from that single number.
- Days: the raw difference between the two dates, optionally adding 1 when "include end date" is on (useful for counting inclusive spans like school terms or billing periods).
- Weeks: total days divided by 7. The decimal part of this number tells you the leftover days - 0.5 weeks is 3.5 days.
- Hours, minutes, seconds: multiply days by 24, 1,440 and 86,400 respectively. These totals assume full 24-hour days; they do not account for time zones, daylight-saving changes, or the specific time of day each event occurred.
- Calendar breakdown (years, months, days): counts whole years first, then whole months in the remaining period, then the leftover days. Because months have different lengths, this is not simply dividing by 30 - the calculator steps through the calendar month by month to give an exact answer.
- Working days: sweeps the range and counts only Monday-through-Friday days, skipping Saturdays and Sundays. Public holidays are not excluded (they vary by country and region).
Include end date: when to turn it on
By default the calculator counts the start date but not the end date, which is standard for "how many days from A to B" questions. For example, the number of days from January 1 to January 7 is 6 by this convention - the same logic a calendar uses when measuring the gap between two events.
Turn "include end date" on when you are counting a period where both the first and last days matter: the duration of a hospital stay, a school term from the first class day to the final exam day, or an employment period where both the hire date and last date of work are paid days. Adding 1 to the result gives you the total number of days the period covers.
Working days vs. calendar days
Calendar days and working days tell different stories. A seven-day calendar week contains exactly five working days. A 30-day calendar month contains roughly 21 to 23 working days depending on where the weekends fall.
Working-day counts matter for:
- Project planning: a 90-day project timeline contains about 65 actual working days, not 90.
- Legal deadlines: many court, contract and regulatory deadlines are stated in business days rather than calendar days.
- Payroll periods: bi-weekly payrolls run for 10 working days per pay period.
- Delivery estimates: couriers quote shipping in business days; a "5-business-day" window covers a full calendar week.
This calculator excludes Saturdays and Sundays. It does not exclude public holidays because those differ by country, state and employer. For deadline calculations in a specific jurisdiction, check whether the relevant rule counts public holidays as non-working days.
Leap years and calendar accuracy
The calculator accounts for leap years automatically. A year is a leap year if it is divisible by 4 but not by 100, or if it is divisible by 400. This means 2000 and 2400 are leap years, but 1900 and 2100 are not. February has 29 days in a leap year and 28 in all others.
The calendar breakdown (years, months, remaining days) steps through each month individually to respect its actual length, so the result is accurate for any date range, including those that cross multiple leap years. The total-days count is always precise - it is computed from the exact day numbers, not from an approximation like "365.25 days per year".
Common time spans for reference
| Period | Calendar days | Working days (approx.) |
|---|---|---|
| 1 week | 7 | 5 |
| 2 weeks | 14 | 10 |
| 1 month (30-day) | 30 | 22 |
| Quarter (3 months) | 91 | 65 |
| 6 months | 182 | 130 |
| 1 year (non-leap) | 365 | 261 |
| 1 year (leap) | 366 | 262 |
| 2 years | 730 | 522 |
| 5 years | 1,825 | 1,305 |
| 10 years | 3,652 | 2,610 |
Approximate day counts for frequently searched intervals.
Frequently asked questions
How do I calculate the number of days between two dates?
Subtract the earlier date from the later date. In practice, convert both dates to a day number (days since a fixed epoch), then take the difference. This calculator does that automatically and also breaks the result into weeks, months, years, hours, minutes and seconds.
Does the calculator count the start date, the end date, or both?
By default it counts the start date but not the end date (exclusive end). This is the standard convention for durations - the same way a calendar measures the gap between two events. Toggle "include end date" to add 1 and count both endpoints, which is useful for inclusive spans like employment periods or hospital stays.
How many working days are between two dates?
Working days are Monday through Friday. To count them, take the total calendar days and subtract the weekend days that fall in the range. A rough rule is to multiply calendar weeks by 5, then handle the partial week at each end. This calculator does the exact count. Note that public holidays are not excluded because they vary by country and employer.
How does the years-months-days breakdown work?
The calculator counts whole years from start to end first, then counts whole calendar months in the remaining period, then counts the leftover days. Because months have different lengths, this is more accurate than dividing the total days by 30. For example, the period from January 31 to March 1 is 1 month and 1 day (or 2 days in a leap year), not simply 29 or 30 days.
What if I enter the end date before the start date?
The calculator automatically swaps the order and computes the absolute difference, so you always get a positive result. The start and end labels refer to the chronological order, not the order you entered them.
How many days are in a year?
A common (non-leap) year has 365 days. A leap year has 366. Because leap years occur roughly every 4 years, the average is about 365.2425 days per year under the Gregorian calendar. This calculator uses exact day counts rather than this average, so results are always precise.
Can I use this to count how many days until a future date?
Yes. Set the start date to today and the end date to the future date you are counting toward. The result shows the exact number of days remaining, along with the breakdown in weeks, hours, minutes and seconds.