0 free tools
How many days until the deadline? How old is someone born on 14 March 1998, in days? What date is 90 business days from Tuesday? Calendar arithmetic sounds trivial until leap years, month lengths and weekends get involved — which is exactly what these date and time calculators handle. The lineup includes an age calculator, days between dates, a business days calculator that skips weekends, hours worked and time card tools for payroll, and a Unix timestamp converter for developers reading raw log files.
Freelancers reach for the hours-and-pay tools when invoicing, HR teams count business days for notice periods, event planners run countdowns, and anyone filling in an official form eventually needs an exact age in years, months and days.
The leap-year rule trips people up more than anything else: a year divisible by 4 is a leap year, except century years, which must be divisible by 400. So 2000 had a February 29 but 1900 did not — a wrinkle that silently breaks long date ranges counted by hand.