Date Difference Calculator
Calculate the exact difference between two dates or datetimes — in years, months, weeks, days, hours, minutes, and seconds. Includes working business days and handles leap years automatically.
Date & Time Difference Calculator
Calculate exact interval between two timestamps with calendar-accurate leap year and time math.
Pick both dates on one calendar. Tap the month title to choose a year, then a month.
How to Calculate the Difference Between Two Dates
Calculating the exact span between two calendar dates involves determining full years, months, and leftover days while respecting variable month lengths (28–31 days) and leap years. Our calculator deconstructs the interval into calendar units and also provides absolute totals in days, hours, minutes, and seconds.
Calendar Breakdown
Years, months, weeks, and days — mirroring how humans naturally express duration.
Total Units
Total days, hours, minutes, and seconds as continuous absolute values for programmatic use.
Working Days
Net Monday–Friday business days and weekend days counted separately within the span.
Frequently Asked Questions
How do I calculate the number of days between two dates?
Count the full years, months, and leftover days between the two dates, or subtract the Julian day numbers. The fastest way is the calculator above: pick a start and end date (with optional times), and it returns the exact number of days, weeks, months, and years, plus working business days — handling leap years automatically.
How does a date calculator handle leap years?
The engine applies the full Gregorian leap-year rule: a year is a leap year if divisible by 4, except century years which must also be divisible by 400. February 2000 had 29 days; February 1900 had 28. Spans crossing February 29 are therefore counted with the correct extra day, and an "Include end day" result includes it when it falls on the boundary.
How many weeks are between two dates?
Divide the total number of days by 7: the whole number is full weeks and the remainder is extra days. For example, January 1 to March 15, 2026 is 73 days, which is 10 weeks and 3 days. The calculator shows this weeks-and-days breakdown alongside the total days automatically.
Does the business days count include public holidays?
No. Business days here are Monday through Friday within the span, with Saturdays and Sundays counted separately as weekend days. Public holidays vary by country and region, so subtract any that fall inside your range to get the final working-day total.
What does "Include end day" mean?
By default the end date is excluded (e.g. Jan 1 to Jan 3 = 2 days). Checking "Include end day" counts it too (= 3 days), which is common for event durations and school calendars.
What is a date to date calculator?
A date to date calculator measures the number of days, weeks, or months that separate two specific calendar dates. It is commonly used for project timelines, countdowns, age checks, and financial calculations.