Online date calculators for days between dates, business days, exact age, countdown timers, and timezone conversion. Free and private.
Every calculator here works on calendar dates, not on timestamps. That distinction matters more than it sounds: a timestamp measures elapsed time, while a calendar date is a label on a day. Two dates can be one day apart and 23 hours apart at the same time, because a daylight saving change makes that day shorter.
Working in calendar dates is what makes these tools agree with a paper diary. It also means the results are stable: the number of days between 1 March and 1 April does not change depending on the time of day you ask, or on which device you ask from.
The rules differ between the tools, and each page states its own. The days-between calculator counts the interval, so the same date returns zero. The business days calculator removes weekends and excludes the start date. The countdown works in whole days only. The time zone converter is the exception: it has to work in instants, because that is what a time zone actually shifts.
Where a tool cannot do something — public holidays, historical dates, a full city search — the page says so rather than guessing. A calculator that quietly returns a plausible but wrong number is worse than one that admits its limits.
Days Between Dates Calculator
Calculate the number of days between two dates.
Business Days Calculator
Count business days between two dates, excluding Saturdays and Sundays.
Age Calculator
Calculate exact age in years, months, and days from a date of birth.
Countdown Calculator
Count the days until a target date, or the days since a past date.
Time Zone Converter
Convert a time between major world time zones, with daylight saving applied.