Date and Time Calculator Suite
Complete date and time calculation suite with working days, age, and world time conversion.
- Runs in your browser
- Free, no signup
Days Between Dates
Calculated Duration
Add or Subtract Time
Target Date
Working Days Calculator
Business Days Summary
Age & Date Difference
Calculated Age
Time Zone Converter
Converted Time
All date and time calculations run in your browser. No dates, birthdates, or schedules are transmitted to our servers.
Working with dates and times across business contracts, project deadlines, employee age verification, and international meetings requires precision.
This calculator suite provides five purpose-built modes: Days Between Dates, Add/Subtract Time (with leap year and month-end clamping), Business Working Days (with custom weekend and holiday exclusions), Exact Age Calculation, and Global Time Zone Conversion.
How to use this tool
- Choose a calculation mode from the top switcher (Days Between, Add/Subtract, Working Days, Age, or Time Zones).
- Fill in the dates, quantities, or locations relevant to your calculation.
- Toggle inclusive or exclusive day counting or select weekend definitions as needed.
- Copy the resulting breakdown with one click.
Month-End Clamping and Leap Year Rules
Adding one month to January 31st cannot produce February 31st because February only has 28 or 29 days.
This engine uses financial end-of-month clamping: adding 1 month to January 31 produces February 28 (or 29 in a leap year), rather than silently overflowing into March 3.
Custom Business Days and Holiday Schedules
Different companies and countries observe different work weeks (e.g. Saturday-Sunday vs Sunday only).
The Working Days mode allows you to configure your exact weekend schedule and paste custom comma-separated holiday dates (in YYYY-MM-DD format) to ensure payroll and milestone estimates are exact.
Frequently asked questions
Does the Days Between Dates mode include both the start and end dates?
You can toggle between Inclusive (counts both the start and end date) and Exclusive (counts the duration between the dates, which is standard for elapsed calendar days).
How does the Age Calculator compute months and days?
It accounts for the exact varying day counts of each intervening calendar month and leap years to calculate completed years, completed months, and remaining days.
Does the time zone converter handle Daylight Saving Time (DST)?
Yes. It leverages standard IANA time zone databases via the browser's native internationalization engine, automatically applying DST offsets.