Free Date & Time Tools
Free online date and time tools for calculations, conversions, and planning. Calculate age, count days, convert timestamps — all in your browser.
Available Tools
Add/Subtract Time
Add or subtract hours, minutes, seconds from a time
Age Calculator
Calculate exact age from birthdate in years, months, days
Business Days Calculator
Count business days between two dates
Calendar Generator
Generate printable calendars for any month or year
Countdown Timer
Create countdown timers to specific dates and times
Date Calculator
Add or subtract days, weeks, months, years from dates
Date Difference in Units
Calculate difference between dates in years, months, days
Date Pattern Finder
Find repeating patterns in date sequences
Date Range Calculator
Calculate start and end dates for given ranges
Day Counter
Count days between two dates including exclusions
Day of Week Finder
Find what day of the week any date falls on
Leap Year Checker
Check if a year is a leap year
Military Time Converter
Convert between 12-hour and 24-hour time formats
Seconds Converter
Convert seconds to hours, minutes, days format
Sunrise/Sunset Calculator
Calculate sunrise and sunset times for any location
Time Duration Calculator
Calculate duration between two times
Time Until Calculator
Calculate time remaining until a future date
Week Number Calculator
Find ISO week number for any date
Need More Time Tools?
Check out our timestamp tools, timezone tools, or calendar tools for more utilities.
What These Date & Time Tools Do
This is a collection of 18 free date and time tools that run entirely in your browser. No software installation, no subscriptions, no waiting. You pick dates or times, click a button, and get results instantly.
The tools cover four main workflows: calculating durations and differences (age, business days, time between dates), adding and subtracting time (days, hours, seconds), converting between formats (Unix timestamp, military time, seconds), and finding date information (day of week, week number, leap year, sunrise/sunset).
How to Use These Tools
Most tools follow the same pattern:
- Select a date using the picker or enter manually
- Choose your calculation or conversion type
- Adjust settings like time format or exclusions
- View results and copy or download
Everything happens client-side using JavaScript. Your data stays in your browser tab and never touches any server.
Who Uses These Tools
HR and payroll teams calculate employee age for benefits, count business days for PTO requests, or determine tenure for anniversaries.
Project managers compute project durations, find end dates from start dates, or calculate time remaining until milestones.
Developers convert Unix timestamps for debugging, calculate time differences for logging, or validate date calculations in code.
Event planners create countdown timers, find day of week for venue booking, or calculate sunrise/sunset for outdoor events.
Tool Categories
Age and Duration
Age Calculator computes exact age from birthdate. Day Counter counts days between dates. Time Duration Calculator finds duration between two times. Date Difference in Units breaks down differences into years, months, and days.
Date Arithmetic
Date Calculator adds or subtracts days, weeks, months, and years. Add/Subtract Time handles hours, minutes, and seconds. Business Days Calculator counts weekdays excluding weekends and holidays.
Date Information
Day of Week Finder returns the weekday for any date. Week Number Calculator gives ISO week numbers. Leap Year Checker identifies leap years. Date Pattern Finder detects repeating sequences. Sunrise/Sunset Calculator computes solar times by location.
Time Conversion
Unix Timestamp Converter translates between epoch timestamps and readable dates. Military Time Converter switches between 12-hour and 24-hour formats. Seconds Converter transforms raw seconds into hours, minutes, days.
Planning and Countdowns
Countdown Timer creates live timers to events. Time Until Calculator shows remaining time to future dates. Calendar Generator produces monthly/yearly calendars. Date Range Calculator determines start and end dates for periods.
Limitations and Gotchas
Time zones: Tools use your browser's local time zone by default. For UTC calculations, specify explicitly.
Business days: Holiday calendars vary by country. Tools use a generic weekend exclusion — add your own holiday list for accuracy.
Sunrise/sunset: Calculations are approximate and don't account for atmospheric conditions or elevation.
Unix timestamps: JavaScript uses milliseconds since epoch. Some systems use seconds. Tools handle both but verify your input format.
Why 1000freetools
Date math is harder than it looks. How many days between March 15 and June 3? What date is 90 days from today? Is 2028 a leap year? You could open a calendar app, fire up a spreadsheet, or write a quick script. Or you could use these tools — focused utilities that do one calculation well without requiring software installation or exposing your data. Everything runs in your browser. No account, no sync, no upsells.