Date Difference Calculator
Calculate the number of days, weeks, months, and years between two dates.
How this calculator works
How to use this calculator
Select a start date and an end date, then click Calculate Date Difference. The calculator shows the number of days between the two dates and approximate weeks, months, and years.
Formula used
The calculator converts both dates to UTC midnight, subtracts the start date from the end date, and divides the result by the number of milliseconds in one day. Months and years are approximate because calendar months and years vary in length.
Example calculation
From January 1, 2026 to January 31, 2026, the difference is 30 days, or about 4.29 weeks.
What the result means
The day result is the exact number of calendar days between the two selected dates. The month and year values are approximate conversions for easier understanding.
Frequently asked questions
Does it include the end date?
The main result shows the difference between dates, so January 1 to January 2 is 1 day.
Why are months approximate?
Months can have 28, 29, 30, or 31 days, so the calculator uses an average month length.
Can I select dates in any order?
Yes. The calculator returns the absolute difference between the two dates.