Fast, honest date calculators

10 free tools that answer one date question at a time: exact ages, day counts, countdowns, and deadlines. No signup, and every calculation runs in your browser, so the dates you enter never leave your device.

Dates

Age Calculator

Your exact age in years, months, and days, plus your next birthday.

Days Between Dates

The exact day count between any two dates, with weeks and months breakdowns.

Add or Subtract Days

What date it will be 30, 90, or any number of days from any start date.

Day of the Week

Find the weekday of any date, past or future.

Deadlines & Planning

Countdown

How many days until any date, in days, weeks, and hours.

Business Days

Working days between two dates, excluding weekends and holidays.

Week Number

The ISO week number of any date, and how many weeks the year has.

Time & Technical

Time Duration

Hours and minutes between two times, with timesheet decimal hours.

Unix Timestamp

Convert Unix timestamps to readable dates and back.

Leap Year Checker

Check any year, see why, and find the next leap years.

Why DaySums?

Date questions deserve instant answers, not popups and signups. Every DaySums tool loads fast, works on any device, explains the convention it uses (inclusive or exclusive counting, which day counts as day one), and does all of its math locally in your browser. We never see, store, or transmit the dates you enter.