What this calculator does
The gap between two dates is a subtraction, but the answer is wanted in several units at once and only one of them is exact. Days are exact. Weeks are exact. Months and years are approximations here, because neither has a fixed length, so they are given from average lengths and labelled as approximate.
The business-day count is the figure that most often differs from expectations. Between 1 January 2026 and 1 January 2027 there are 365 calendar days but only 261 business days, because 104 of them fall on weekends. Public holidays are not deducted, so use the working days calculator if you need those taken out.
The formula
The two dates are converted to a day count and subtracted. Weeks divide that by 7. The approximate months and years figures divide by 30.4375 and 365.25, the average lengths once leap years are spread across the cycle. The business-day count steps through each day in turn and counts the ones that are not a Saturday or Sunday.
| Term | Meaning |
|---|---|
| Calendar days | Every day in the range, an exact count. |
| Business days | Weekdays only, with Saturdays and Sundays excluded but no allowance for holidays. |
| Approximate months | Days divided by 30.4375, the average month length across a four-year cycle. Not a count of calendar months. |
The inputs explained
| Field | What to enter |
|---|---|
| Start date | The start date. |
| End date | The end date. Entering a date before the start gives the same gap, reported as a positive number. |
When to use it
Working out a notice period or deadline
Contracts specify periods in days, weeks or months, and knowing which of those the count actually satisfies matters when the deadline is close.
Counting down to an event
The days and weeks figures are the ones people want for a countdown, and the business-day figure is the one that matters if the preparation happens at work.
Measuring an elapsed period for a claim or record
Insurance, warranty and employment periods are usually counted in days, and an exact figure avoids arguments about how a month was interpreted.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How many days and business days from 1 January 2026?
A range of end dates, all counted from the same fixed start of 1 January 2026.
| End date | Days | Business days | Weeks | Months (approx.) |
|---|---|---|---|---|
| 2026-01-08 | 7 | 5 | 1.00 | 0.23 |
| 2026-02-01 | 31 | 21 | 4.43 | 1.02 |
| 2026-04-01 | 90 | 64 | 12.86 | 2.96 |
| 2026-07-01 | 181 | 129 | 25.86 | 5.95 |
| 2027-01-01 | 365 | 261 | 52.14 | 11.99 |
Questions
Does the count include the start date, the end date, or both?
Neither end is double-counted: the result is the number of days you would have to add to the start date to reach the end date. Counting 1 January to 8 January gives 7, not 8. If your purpose needs both endpoints counted, such as a hotel stay measured in nights against days, add one.
Why are the months and years figures marked approximate?
Because months and years vary in length. The calculator divides by average lengths of 30.4375 days and 365.25 days, which is accurate across long periods but will not match a calendar-month count exactly over a short one. For exact calendar months, use the date addition calculator instead.
Are public holidays excluded from the business-day figure?
No, only weekends. Holidays vary by country, state and year, so they cannot be applied automatically. The working days calculator takes a holiday count as an input and deducts it.
What if I enter the dates the wrong way round?
The result comes back the same, as a positive figure. The calculator reports the size of the gap rather than its direction.
To deduct public holidays as well as weekends, see the working days calculator. To find the date a set period away rather than the gap between two, see the date addition calculator.