Count the days between two dates, or add and subtract days, weeks, months and years.
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How to use the date calculator
Two modes cover almost every date question you'll run into.
1
Days between two dates
Pick a start and end date to see the exact number of days between them, plus the same span expressed in weeks, in weekdays, and as years, months and days.
2
Add or subtract time
Choose a start date, then add or subtract any number of days, weeks, months or years. Handy for finding a due date, a deadline 90 days out, or a date 6 months ago.
3
Read the breakdown
The result shows the plain day count, the inclusive count (both endpoints), weeks, and the number of business days — so you get the right figure for whatever you're measuring.
Days between dates, weeks, and business days
A "date calculator" usually answers one of two questions: how far apart are two dates, or what date falls a certain distance from another. This tool does both. In difference mode you get the number of days between the two dates — the figure most people mean by "days between dates" — and because a raw day count isn't always what you need, it's also broken down into weeks and into years, months and days.
The weekday (business-day) figure counts only Monday through Friday within the span. It's a quick way to estimate working days for a project or a leave request, but it doesn't subtract public holidays, which differ by country. For contracts and shipping estimates, check the relevant holiday calendar separately. If you want a live countdown to a single future date rather than the span between two, the days until counter does that instead.
Adding months and years is where naive date math often goes wrong: adding one month to January 31 has no "February 31," so the calculator clamps to the last valid day (February 28 or 29 — the leap year checker settles which). Adding a year to February 29 lands on February 28 in a common year. These rules match how spreadsheets and databases handle date arithmetic, so your results stay consistent.
Calendar days are every day on the calendar, weekends and public holidays included. Business days (also called working days) are Monday to Friday only, minus public holidays. So calendar days are not business days: a deadline of 10 calendar days is always shorter than one of 10 business days.
Business days to calendar days: every 5 business days spans a full 7-day week, so 5 business days is 7 calendar days, 10 is 14 and 20 is 28, before any holidays. Each public holiday in the span adds one more calendar day.
Calendar days to business days: multiply by 5/7 as a rough guide. A 30-day span holds 20 to 22 weekdays, depending on the weekday it starts on, and fewer if a holiday falls inside it.
When a calendar-day deadline lands on a weekend: it depends on the rules you are under. US federal court deadlines, for example, roll forward to the next day that is not a weekend or legal holiday (Federal Rule of Civil Procedure 6), while many contracts and delivery promises do not. Check the wording before relying on either.
For an exact count between two dates, use Days between mode above: it shows the calendar-day total and the weekday count side by side. Then subtract the public holidays that fall in the span.
Frequently Asked Questions
How do I calculate the number of days between two dates?
Enter the start date and the end date in the "Days between" mode above. The calculator instantly shows the exact number of days between them, along with the count in weeks, the number of weekdays (business days), and a breakdown in years, months and days. The plain day count runs from the start date to the end date and does not include the start day itself, so 1 March to 8 March comes out as 7 days rather than 8. For the ISO week each of those dates falls in, the week number tool takes any single date.
Does the day count include both the start and end dates?
By default it shows the number of days from the start date to the end date, which does not count the start day itself. To include both endpoints — for example, counting how many days you're staying somewhere — use the Days (incl. both) figure, which adds one.
How do I add or subtract days from a date?
Switch to "Add / subtract" mode, choose a start date, enter an amount, pick a unit (days, weeks, months or years) and whether to add or subtract. The result date and its weekday appear instantly. Month and year math lands on the same day number where possible, clamping to the last day of the month when needed.
How are business days counted?
The weekday count includes every Monday to Friday in the span and excludes Saturdays and Sundays. It doesn't account for public holidays, which vary by country, so treat it as a working-day estimate. A full 7-day week holds 5 weekdays, so a 30-day span works out to between 20 and 22 of them depending on which weekday it starts on. Subtract your own country's public holidays from that figure to get a true working-day count — the United States has 11 federal holidays and England and Wales have 8 bank holidays.
Are calendar days the same as business days?
Calendar days and business days are not the same. Calendar days count every day, including Saturdays, Sundays and public holidays, while business days count only Monday to Friday and skip public holidays. Every 5 business days covers 7 calendar days, so 10 business days is about 14 calendar days, and 30 calendar days holds only 20 to 22 business days. The Days between mode shows both counts for any two dates.
Is my data sent anywhere?
The date calculator sends nothing anywhere — all the date math runs locally in your browser. The dates you enter are never uploaded to a server. Once the page has loaded, the tool keeps working offline.