Time & Date calculators
Calculate dates, durations, ages, time zones, and calendar intervals.
Tool map
What are you trying to work out?
A useful place to start
Use date tools for calendar boundaries and duration tools for elapsed time. Check whether endpoints and time zones are included.
Age Calculator
Calculate exact age in years, months, and days from a birth date to any age-at date, plus total months, weeks, days, weekday born, and next birthday.
Gestational Age Calculator
Estimate gestational age in weeks and days, due date, trimester, conception date, milestones, and prenatal timing from LMP, conception, or ultrasound dating.
Julian Date Converter
Convert mixed-calendar civil UTC dates to astronomical Julian Date forms, or convert a Julian Date back to UTC.
Pregnancy Conception Calculator
Estimate a likely conception date, possible conception range, and due date from an estimated due date, last period, cycle length, or ultrasound dating.
Reverse Due Date Calculator
Work backward from a pregnancy due date to estimate last menstrual period, likely conception timing, trimester boundaries, milestones, and appointment windows.
8 Hour Shift Calculator
Calculate shift start and end times for eight hour schedules, overnight work, and unpaid breaks using precise 24-hour clock math.
Time Card Calculator
Calculate weekly time card hours, regular hours, overtime hours, and unpaid lunch deductions for selected workdays.
Time Duration Calculator
Calculate the duration between two clock times, add time, subtract time, and convert results into hours, minutes, and seconds.