Date Calculator
Calculate the time difference between two dates.
Time Difference
0
Days
0
Weeks
0
Months
0
Years
Date Facts
1 week = 7 days
1 month ≈ 30.44 days
1 year = 365 days
Leap year = 366 days
Frequently Asked Questions
How do I calculate days between dates?
Simply enter a start date and an end date, and the calculator will show you the exact number of days, weeks, and months between them.
Does the calculator include the end date?
By default, the calculation includes the start date but not the end date. You can toggle this setting if needed.
How many days are in a year?
A regular year has 365 days, while a leap year has 366 days. The calculator automatically accounts for leap years.
Overview
A date calculator handles the small but surprisingly tricky math of counting days, weeks, months, and years between two points in time, or projecting a date a number of days, weeks, or months in the future or the past. Manual counting fails around month boundaries, leap years, and long spans. This tool handles all three by working with standard calendar rules, including leap years and variable month lengths.
Common use cases include figuring out a project deadline, counting down to a wedding or anniversary, calculating the duration of a pregnancy, planning a visa or passport window, or working out the age of a child in years and months. It is also handy for legal and finance questions that hinge on exact day counts, such as notice periods, rental terms, or interest accrual. Two related calculations show up a lot: how many days has it been since a specific event, and what date falls 90 (or 14, or 180) days from today.
One thing worth flagging is the difference between calendar days and business days. Calendar days count every day, weekends included. Business days (also called working days) typically count Monday through Friday and skip weekends, sometimes skipping local public holidays as well. For deadlines that say 'within 30 days', calendar days is usually the right reading; for delivery estimates or service-level agreements, business days is more common. The calculator makes it easy to switch between the two interpretations rather than guessing.
A practical tip: when adding months, the result follows standard banking behavior, so adding 1 month to January 31 lands on the last day of February, not March 3. Adding days is always exact, and is the safer choice when a deadline cannot be ambiguous. For very long spans, prefer counting days and converting to years and months yourself, since month arithmetic gets fuzzy past 24 months due to variable month length.
How to use
- Pick a mode: count the gap between two dates, or add or subtract a number of days, weeks, or months from a starting date.
- Enter the start date and, in gap mode, the end date; in add/subtract mode, enter the unit and amount (for example, 45 days or 3 months).
- Choose whether to count in calendar days or business days, and whether to include the end date in the count.
- Read the result, which usually shows years, months, weeks, and days at the same time, and check the optional weekday label for sanity.