How to use the Date Calculator
- Use the buttons at the top to pick Time between two dates or Add or subtract days.
- To measure the time between two dates, pick a start date and an end date. You'll get the total number of days, the result in weeks and days, the result in months and days, and the number of weekdays and weekend days.
- If you need to count both the first and the last day, as you would for a contract term or a vacation, check Include end date.
- To find a date before or after another date, enter a start date, a number and a unit (days, weeks, months or years). You'll get the resulting date and its day of the week. The quick-pick buttons show dates such as 90 days or 6 months out in one click.
Counting days between two dates: include the end date or not?
The number of days between two dates is end date − start date. From March 1 to March 10 is 9 days, meaning that 9 days after March 1 is March 10.
For vacation days, hotel stays or contract terms, you usually count both the first and the last day, so you add 1. A vacation from March 1 to March 10 is 10 days. Turn "Include end date" on or off to match what you're measuring.
| What you're measuring | Include end date? | Example: Mar 1 – Mar 10 |
|---|---|---|
| Days elapsed or days remaining | No | 9 days |
| Vacation, business trip or travel days | Yes | 10 days |
| Length of employment or a contract | Yes (usually) | 10 days |
Adding months to a date and the end-of-month rule
Adding months needs some care because months have different lengths. This calculator keeps the same day of the month. If that day doesn't exist in the target month, it uses the last day of that month instead.
- January 31, 2026 + 1 month → February 28, 2026
- March 31, 2026 + 1 month → April 30, 2026
- February 29, 2024 + 1 year → February 28, 2025
"90 days from now" and "3 months from now" aren't the same thing either. Starting from January 1 in a non-leap year, both land on April 1. Starting from March 1, though, 90 days later is May 30, while 3 months later is June 1. Before you work out a deadline, check whether it's stated in days or in months. Return windows, notice periods and visa stays often use one or the other.
How weekdays are counted, and what about holidays?
Weekdays are the days in the range that aren't Saturday or Sunday. Every 7 days contain 5 weekdays, so the calculator multiplies the number of full weeks by 5, then adds any weekdays among the leftover days.
The calculator doesn't remove public holidays. If your range includes holidays such as Thanksgiving, Christmas, New Year's Day, bank holidays or Canada Day, or holidays that move from year to year like Easter Monday or Memorial Day, subtract them from the result yourself. Remember that a holiday falling on a weekend often gives a substitute day off on a weekday. This matters most for business-day deadlines, such as "processed within 10 business days" or "delivery in 5–7 working days."
Common uses
- Deadlines: find the date 30, 60 or 90 days after an invoice, an order or a notice.
- Countdowns: see how many days are left until a trip, a due date or an event.
- Work and contracts: measure a period of employment or a lease in months and days.
- Planning: count the working days available for a project, minus any holidays.