Choose how to count the dates
- Enter start and end dates in either order.
- Choose elapsed date boundaries or include both calendar dates.
- Calculate, compare the day count and weeks, then copy or download your result.
Elapsed and inclusive examples
Elapsed days = absolute difference between the two calendar dates. Include both dates = elapsed days + 1. Counted days and weeks are nonnegative for either input order; signed elapsed days show direction separately.
From 2024-02-28 to 2024-03-01 there are 2 elapsed days, or 3 included dates: February 28, February 29 and March 1. Identical dates have 0 elapsed days or 1 included date. Reversed dates keep the same count but give a negative signed elapsed difference.
For seven-day units, complete weeks = floor of count ÷ 7, with the remainder shown as days. Fourteen counted days give 2 complete weeks. Decimal weeks = counted days ÷ 7: 17 days give 2 complete weeks and 3 days, or about 2.428571 total weeks. These are fixed seven-day units, not numbered calendar weeks.
Calendar, limits and privacy
Dates use Gregorian rules consistently for 0001-01-01 through 9999-12-31. The U.S. Naval Observatory explains the leap-year rule: century years must be divisible by 400, so 1900 and 2100 are not leap years and 2000 is.
This counts calendar dates rather than elapsed 24-hour periods. Time of day, time zone, daylight-saving transitions, weekends and holidays are not applied. Gregorian rules are used even before historical adoption. This does not establish a legal deadline or billable duration; check which endpoints your task requires.
Inputs stay in browser memory without uploads or saved dates. CSV includes ISO dates, the selected rule, counted days, whole/decimal weeks and signed elapsed days. Decimal weeks show up to six decimal places; CSV uses six decimal places. Reset restores the examples and elapsed counting, and clears results. Undo action restores both dates and the counting rule before Today, Swap, Reset or a result-card rule change. Editing begins a new state. Use Choose on a result card to recalculate with that rule without returning to the form.
Should I include both dates?
Choose it when you need to count every named calendar date in the range. Choose elapsed days when you need the number of date boundaries crossed. The calculator does not infer your contract or scheduling rule.
Does inclusive counting change signed elapsed days?
No. Signed elapsed days always remain end minus start; only the nonnegative counted days and derived weeks use the chosen inclusion rule.