Day Counter - Count Days Between Dates
Choose a mode: count the days between two dates, find a date that is a set number of days from your start, or subtract days to discover an earlier date. You get the total span in days, weeks, months, weekdays, and weekend days - all updating as you type.
How the day counter works
This calculator operates in three modes. In "Days between two dates" mode it subtracts the earlier date from the later date to produce a raw calendar-day count, then optionally adds one if you want the end date itself included (inclusive counting). In "Add days" mode it advances the start date by the number of days you enter. In "Subtract days" mode it moves the start date backwards by that amount. Across all three modes you can turn on the business-days toggle to skip Saturdays and Sundays, which is useful for deadline planning, invoice terms, and legal notice periods.
Calendar days vs. business days
A calendar day is any day of the week, Monday through Sunday. A business day (also called a working day) is any weekday that is not a Saturday or Sunday. In a standard 7-day week there are exactly 5 business days. Over a full year of 52 weeks that gives 260 business days, with a few extra depending on how public holidays fall. The calculator counts weekdays by dividing the span into full weeks (5 weekdays each) plus the remaining partial week, so the result is exact to the day. Public holidays are not excluded by default, because they vary by country and employer. If your workflow requires holiday exclusions, note the holiday dates separately and subtract them from the business-day count shown here.
Inclusive vs. exclusive counting
Whether to include the end date depends on the context. If you are counting the days left until a deadline, you typically want the exclusive count: January 1 to January 10 is 9 days away. If you are billing for every day a service was active, including both the first and last day, you use the inclusive count: January 1 to January 10 is 10 days of service. Legal and financial contracts usually specify which convention applies; when in doubt, check the wording. The toggle on this calculator lets you switch between the two in one click.
Common uses
Day counters are used across many areas of daily life. Project managers track sprint length and delivery windows in working days. HR teams calculate probationary periods, notice periods, and annual leave accrual. Legal documents set response deadlines in calendar days. Loan and credit agreements quote interest in exact days to the cent. Parents count down to birthdays and school holidays. Scientists date-stamp data in whole days for reproducibility. Whatever the reason, the calculation itself is always the same: a signed difference between two dates, optionally filtered to weekdays only.
Common date spans at a glance
| Period | Calendar days | Business days (approx.) |
|---|---|---|
| 1 week | 7 | 5 |
| 2 weeks | 14 | 10 |
| 1 month (avg.) | 30-31 | 21-23 |
| 1 quarter (avg.) | 91 | 65 |
| 6 months (avg.) | 182 | 130 |
| 1 year | 365 (366 leap) | 260-262 |
| 2 years | 730 (731 leap) | 520-524 |
Approximate calendar-day and business-day counts for frequently referenced periods.
Frequently asked questions
How do I count the days between two dates?
Subtract the earlier date from the later one. Computers store dates as a count of milliseconds from a fixed reference point, so the difference in milliseconds divided by 86,400,000 (one day) gives you the gap in whole days. This calculator does that for you instantly: enter your start and end dates and read off the result.
Does the day count include the start date and end date?
By default this calculator uses exclusive end-date counting: it counts the days from the start up to (but not including) the end date. Turn on the "Include end date in count" toggle to switch to inclusive counting, which adds 1 to include both the first and last day. Exclusive is standard for "days until" questions; inclusive is common for billing periods.
What is the difference between calendar days and business days?
Calendar days count every day of the week, including Saturdays and Sundays. Business days count only Monday through Friday. In a typical week there are 7 calendar days and 5 business days. Toggle "Business days only" on this calculator to switch between the two modes.
How many days are there in a year?
A common year has 365 days. A leap year, which occurs every 4 years (with minor exceptions for century years), has 366 days. The extra day is February 29. If your date span crosses a February 29, the calculator accounts for it automatically.
Can I calculate what date is 90 days from today?
Yes. Select "Add days to a date" from the mode selector, enter your start date (today), and type 90 in the "Number of days" field. The result date updates instantly. Turn on "Business days only" if you need 90 working days rather than calendar days.
How do I find the date 30 days before a deadline?
Select "Subtract days from a date", enter your deadline as the start date, and type 30 in the "Number of days" field. The result date shows you the date exactly 30 days before your deadline, which you can use as a preparation or reminder date.
Why does my day count seem off by one?
The most common cause is inclusive versus exclusive counting. If you expect to count both the first and last day (inclusive), toggle on "Include end date in count" to add 1 to the result. The other common cause is time zones: this calculator treats every date as starting at midnight local time, with no daylight-saving adjustments, so results are always exact whole days.