Date Calculator – Days Between Dates, Add or Subtract Days, Months & Years
Use this free online date calculator to find the exact number of years, months, weeks and days between two dates, or to add and subtract time from any date. You can also switch to business days and set your own weekends and holidays.
Days Between Two Dates
Find the number of years, months, weeks, and days between dates. Click "Settings" to define holidays.
Weekend days (not counted as business days)
Holidays (one date per line, format YYYY-MM-DD)
Add or Subtract from a Date
Enter a start date, then add or subtract years, months, weeks and days.
Business day settings
Years and months are added on the calendar first. Weeks and days are then counted as working days, skipping weekends and holidays.
Weekend days
Holidays (one date per line, format YYYY-MM-DD)
What Is a Date Calculator?
A date calculator is an online tool that does calendar maths for you. Instead of counting days on a calendar, you enter a start date and an end date and instantly get the date difference in years, months, weeks and days. It also works the other way: enter a date and add or subtract days, weeks, months or years to find a future date or a past date.
How to Calculate Days Between Two Dates
Pick a start date and an end date in the first calculator and press Calculate. You will see the full breakdown (for example 1 year, 2 months, 3 weeks, 4 days) along with the total number of days and total weeks. Tick "Include end date" if you want both the first and last day counted, which is common for leave, hotel stays and project timelines.
How to Add or Subtract Days, Weeks, Months and Years
In the second calculator, choose a start date, select Add or Subtract, then enter the years, months, weeks and days. For example, to find the date 90 days from today, enter 0 years, 0 months, 0 weeks and 90 days. This is useful for due dates, warranty expiry, notice periods, loan terms and delivery estimates.
Business Days Calculator (Working Days)
Turn on "Calculate in business days" to skip weekends and public holidays. By default Saturday and Sunday are weekends, but you can change this to match your country, for example Friday and Saturday, or only Sunday. Add your own holiday dates in Settings and the calculator will exclude them. This works as a working days calculator for payroll, invoices, courier deadlines and project schedules.
Common Uses
| Use case | Example |
|---|---|
| Project deadline | Add 30 business days to the kickoff date |
| Age or service duration | Years, months and days from a birth or joining date |
| Pregnancy and baby milestones | Add 40 weeks to a start date |
| Notice period | Add 2 months to a resignation date |
| Countdown | Days left until an event or exam |
| Invoice due date | Add 15 working days to the invoice date |
Frequently Asked Questions
How many days are there between two dates?
Enter both dates in the first calculator. It shows the total number of calendar days and also the breakdown in years, months, weeks and days.
How do I find a date 100 days from today?
Use the second calculator, select Add, enter 100 in the Days box and press Calculate.
Does the calculator handle leap years?
Yes. Leap years and different month lengths are handled automatically.
Can I exclude weekends and holidays?
Yes. Use the business days option and add your holiday dates in Settings.
Is this date calculator free?
Yes, it is completely free and works on mobile, tablet and desktop. No data is stored or sent anywhere.