Calculate the time between two dates or add and subtract days, weeks, months and years from a date.
The standard total excludes the end date. The inclusive total includes both the start and end date.
How to use the Date Calculator
Select Difference between dates to measure the interval between two calendar dates. Choose Add or subtract time when you want to move forward or backward by a set number of days, weeks, months or years. For time-zone and clock conversions, use the United Kingdom Time Calculator.
Understanding the date difference
The result shows the calendar difference in years, months and days, plus the total number of days and weeks. The order of the selected dates does not create a negative result. Instead, the calculator identifies which date comes first and measures the absolute interval.
| Result | Meaning |
|---|---|
| Calendar difference | Complete years, months and remaining days |
| Total days | Elapsed 24-hour date boundaries |
| Inclusive days | Total days plus both boundary dates |
| Weeks and days | Complete seven-day weeks plus remaining days |
Adding and subtracting months or years
Calendar months have different lengths. When a target month does not contain the original day number, the calculator uses the final valid day of that month. For example, adding one month to 31 January produces the last valid date in February. Leap-year adjustments follow the same rule.
Working days and UK bank holidays
This tool calculates calendar dates and does not automatically remove weekends or public holidays. If a deadline depends on working days, check the official UK bank holidays list on GOV.UK and apply any rules set by the organisation handling the deadline.
Other useful calculations
Date ranges can help define the period used in a Carbon Footprint Calculator UK. If you need to compare two quantities after measuring a time period, try the Ratio Calculator. More practical tools are available on the United Kingdom Calculator homepage.
Frequently asked questions
Does the result include the end date?
The standard total excludes the end date. The calculator also displays an inclusive total that counts both dates.
Can I enter the dates in reverse order?
Yes. The calculator measures the absolute interval and shows the earlier and later date in the breakdown.
How are weeks calculated?
Total elapsed days are divided into complete seven-day weeks, with any remaining days shown separately.
Does the calculator exclude weekends?
No. It uses calendar days. Weekend and bank-holiday exclusions must be applied separately when required.
What happens when I add a month to the 31st?
If the target month is shorter, the result uses that month’s final valid date.