Date calculator: days between dates, business days, age
Days between dates, countdowns, exact age, and business days that skip US federal holidays and their observed days off. Calculated as you type, right in your browser.
Days between two dates
Countdown (D-day)
Add / subtract
Business days
Counts working days only, skipping weekends and public holidays (including substitute holidays).
Business-day deadline
Finds a date N business days away, like a shipping or processing deadline. The start date itself isn't counted.
Age calculator
Anniversaries (100 days, 1 year…)
What day of the week?
Week number & day of year
Time between two moments
Public holidays
Date calculation guides
- Days between two dates: when to add 1Inclusive or exclusive counts, countdowns and leap years
- Counting business daysDeadlines like “within 5 business days”, step by step
- Federal holidays on a weekendSaturday moves to Friday, Sunday to Monday: dates for 2026–2028
- Adding months to a dateThe end-of-month rule and monthly schedules
- Exact age in years, months and daysThe counting method, month-end and February 29 birthdays
- ISO week numbersWeek 1, week 53 and why spreadsheets disagree
Frequently asked questions
What does “include start date” mean?
It counts the first day as a day too. From Oct 1 to Oct 3 is 2 days by subtraction, or 3 days if you include the start date. Leave it off for countdowns and “how long ago”; turn it on for periods like “June 1 through June 5”.
Which days are skipped when counting business days?
Saturdays, Sundays and the public holidays of the calendar you pick. With US holidays, that means the 11 federal holidays on the days they are observed: the Friday before when one falls on a Saturday, the Monday after when it falls on a Sunday. Holiday data covers 2015 to 2035.
What’s Jan 31 plus one month?
If the next month has no 31st, the result is that month’s last day, so you get Feb 28 (Feb 29 in leap years).
How is age calculated?
You gain a year on each birthday, and the months and days are counted on from your last birthday. People born on Feb 29 are treated as having their birthday on Feb 28 in other years.
Are the dates I enter sent anywhere?
No. Everything is calculated in your browser. Only your holiday calendar and language choices are remembered on this device. Google ads on the page may use cookies (see the privacy policy).