Date & Time Calculators

Date differences, work hours, timesheets, and countdowns.

Age CalculatorCalculate exact age in years, months, and days from a birth date, plus total days and weeks lived.Date CalculatorAdd or subtract years, months, and days from a start date to find a resulting date.Days Between Dates CalculatorCalculate the exact number of days between two calendar dates.Time CalculatorAdd or subtract hours and minutes from a starting time to find a resulting clock time.Hours and Minutes CalculatorConvert between decimal hours and hours-and-minutes format in either direction.Work Hours CalculatorCalculate total hours worked in a shift, accounting for a clock-in time, clock-out time, and unpaid break.Timesheet CalculatorAdd up daily hours across a week to get total hours, average per day, and overtime.Business Days CalculatorCount the number of weekdays (business days) between two dates, excluding weekends.Week CalculatorCalculate the number of weeks between two dates, or find the ISO week number of any date.Countdown CalculatorCalculate exactly how much time remains until a future date and time.

Choose the right date & time calculator

Start with the question you are trying to answer, then open the calculator built for it.

Ages and date spans

Use Age for exact age, Days Between Dates for the day count between two dates (with an inclusive option) and the same span in years, months, days and weeks.

Deadlines and planning

Use Date Calculator to add or subtract days, months or years, Business Days to skip weekends, Week Calculator for ISO week numbers, and Countdown for time remaining.

Hours and pay

Use Work Hours for the hours between two clock times, with or without an unpaid break, Timesheet for a week with overtime, Hours ↔ Decimal for payroll conversions, and Time Calculator to add or subtract clock time.

Good to know before you calculate

Month lengths vary, so a 'month' can be 28 to 31 days. When a start date falls on the 29th, 30th or 31st, these calculators treat the last day of a shorter month as the anniversary — January 31 plus one month is February 28 (or 29 in a leap year).

Day counts measure elapsed days by default. Many real-world rules count inclusively instead: a hotel stay from the 2nd to the 5th is 3 nights, but a conference over the same dates is 4 days. Days Between Dates lets you choose.

Week numbers follow ISO 8601: weeks start on Monday and week 1 contains the year's first Thursday, so the first days of January can belong to week 52 or 53 of the previous year. Clock-time tools use your device's time zone and wrap past midnight automatically.

Date & Time calculator FAQs

Do the date calculators include the end date?

Most count elapsed days between dates. Days Between Dates has an option to count both the start and end date.

How are month-end dates handled?

When a start date falls on the 29th–31st and the target month is shorter, the last day of that month is used, so January 31 plus one month is February 28 (or 29).

Which time zone is used?

Your device's local time zone. Countdowns and clock calculations use your device's clock.

Which date and time calculator should I use?

Age Calculator: Use it for completed age from a birth date to a chosen date.
Days Between Dates: Use it when you need the distance between two calendar dates. It shows the total number of days and the same gap in years, months and days.
Date Calculator: Use it to add or subtract days, weeks, months, or years from a starting date.
Business Days / Work Hours / Timesheet: Use these for schedules and working time. Remember that holidays, breaks, overtime, and payroll rules can vary.
Time / Hours & Minutes: Use these for clock-time and duration arithmetic, including conversions between decimal hours and hours/minutes.
Countdown / Week Calculator: Use these for future-event countdowns and week-based planning.

Date and time calculations can depend on calendar conventions, time zones, public holidays, and workplace rules. Each calculator explains the assumptions that matter for its result.