How to use the Days Between Dates Calculator
- Choose the start date.
- Choose the end date. It starts as today’s date, and you can change it.
- Read the total number of days, the same gap in weeks, and the gap in years, months and days.
- If the dates are the wrong way round, the calculator swaps them and still shows the gap.
Formula used
Days = (end date − start date) ÷ 86,400,000 ms. Months are counted as whole calendar months from the start date, with the remaining days added.
Worked example
Here is the Days Between Dates Calculator worked through with the example values shown above, so you can check each step by hand.
| Inputs | |
|---|---|
| Start date | 2026-01-01 |
| Result | |
| Total days | 302 |
| In weeks | 43 weeks, 1 day |
| In years, months and days | 0 years, 9 months, 29 days |
How the gap is counted
The calculator counts the number of midnights between the two dates. From 1 January to 30 October 2026 there are 302 days, which is 43 weeks, 1 day, or 0 years, 9 months, 29 days. The end date is not counted, so Monday to Tuesday is one day. If you need both the first and last day counted, for example for a hotel stay billed per day or a leave application, add 1.
Leap years are handled automatically. The year 2028, for instance, has 366 days because February has 29, and the calculator uses the real calendar rather than assuming 365 days per year.
Months and years are calendar-based
The years, months and days breakdown counts whole calendar months from the start date and then adds the remaining days. Because months have 28 to 31 days, the number of days in a month is not fixed, and 9 months can be anywhere from 273 to 275 days.
When the start date is the 31st and a month has fewer days, the calculator uses the last day of that month. This matches how most people count, for example 31 January plus one month is the last day of February.
Everyday uses
People use a date difference to check a notice period, count days left until an exam, calculate interest for a part year, track a project, measure the length of a pregnancy or work out how long they have lived in a place. For example, a 90-day return window that starts on 30 October 2026 ends on 28 January 2027, which you can confirm with the add-days calculator on this site.
For legal or contractual periods, read how the document counts days, because some contracts include the first day, some exclude it, and some count only working days.
Working days and weekends
This calculator counts every calendar day, including weekends and public holidays. To estimate working days, a rough rule is five working days per week, so 302 days is about 43 weeks and roughly 215 working days. This leaves out public holidays, which differ by state and year.
For payroll or legal deadlines, use the exact working-day rules of your employer or the court.
Frequently asked questions
Is the end date included in the count?
No. The result is the difference between the dates, so one day separates 1 January and 2 January. Add 1 to count both days.
What if the start date is after the end date?
The calculator swaps them and shows the positive gap.
Does it handle leap years?
Yes. It uses the real calendar, so 29 February is counted in leap years.
How many days are there in a year?
A normal year has 365 days and a leap year has 366. A leap year occurs every four years, with exceptions for century years not divisible by 400.
Can I count working days?
Not with this tool. It counts all calendar days. Divide by 7 and multiply by 5 for a rough working-day estimate.
How do I find the date after a number of days?
Use the Add or Subtract Days from a Date calculator on this site.
This calculator gives estimates for information only. Actual figures from a bank, employer, tax authority or doctor may differ. It is not financial, tax, legal or medical advice.