CalcKitDate Calculator
Your dates
Leap years are handled correctly: February has 29 days in 2024 and 2028, and 28 days in 2026. The count is the number of days from the start date to the end date.
Example: January 1, 2026 (Thursday) to April 1, 2026 (Wednesday) is 90 days — 12 weeks and 6 days, with 64 weekdays in between.
Behind the numbers
How the date difference is calculated
Both dates are counted as days on the real calendar, including leap years, and the difference is the number of days between them. Adding days works the same way in reverse: the calculator steps forward or back by the number of days you enter, rolling over months and years as needed.
Worked example: January 1 to April 1, 2026 is 31 days (January) + 28 days (February, 2026 is not a leap year) + 31 days (March) = 90 days. And 90 days from January 1, 2026 is April 1, 2026, a Wednesday.
Leap years, at a glance
| Year | Leap year? | February has |
|---|---|---|
| 2024 | Yes | 29 days |
| 2025 | No | 28 days |
| 2026 | No | 28 days |
| 2028 | Yes | 29 days |
A few comparisons
Example date calculations
| Calculation | Result |
|---|---|
| January 1, 2026 → April 1, 2026 | 90 days (12 weeks, 6 days) |
| February 28, 2026 + 1 day | March 1, 2026 (Sunday) |
| February 28, 2028 + 1 day | February 29, 2028 (Tuesday) |
| January 1, 2024 → January 1, 2025 | 366 days (2024 is a leap year) |
| June 15, 2026 + 90 days | September 13, 2026 (Sunday) |
Dates, without the mental math.
Use the days-between mode for deadlines, countdowns and trip lengths, and the add-days mode for due dates and follow-up appointments.
Remember that the count does not include the start date: January 1 to January 2 is 1 day, not 2.
Leap years only change February. A span that crosses February 2024 or 2028 is one day longer than the same span in 2026.
For work planning, the weekdays row counts Monday to Friday only, so a 90-day span from January 1, 2026 is 64 working days, not 90.
Good to know
Your date questions, answered.
How many days are there from January 1, 2026 to April 1, 2026?
There are 90 days between January 1, 2026 and April 1, 2026: 31 days in January, 28 in February (2026 is not a leap year) and 31 in March, which adds up to 90. That is 12 weeks and 6 days, with 64 weekdays (Monday to Friday) in between.
What date is 90 days from January 1, 2026?
April 1, 2026, a Wednesday. Counting 90 days forward from January 1 lands on April 1, because January has 31 days, February has 28 in 2026, and March has 31, which totals 90.
Does the date calculator handle leap years?
Yes. It uses the real calendar, so February has 29 days in leap years like 2024 and 2028 and 28 days in other years. For example, February 28, 2028 plus 1 day is February 29, 2028, while February 28, 2026 plus 1 day is March 1, 2026.
Are the start and end dates counted in the days between?
The count is the number of days you have to move forward from the start date to reach the end date, so the start date itself is not counted and the end date is the last day counted. January 1 to January 2 is 1 day, and January 1 to April 1, 2026 is 90 days.