Web Tools
Date/Time Calculator
Calculate date differences, add or subtract durations, and explore date details. Shows total days, business days, week numbers, and more. Runs entirely in your browser — your data never leaves your machine.
date time calculator duration business-days
Published May 28, 2026
All interactive tools run entirely in your browser. Your data never leaves your device.
How It Works
Choose between three modes: calculate the difference between two dates, add or subtract a duration from a date, or explore detailed information about any date.
Features
- Date Difference: years, months, days, total days, total weeks, and business days between two dates
- Add / Subtract: add or subtract days, weeks, months, or years from any date
- Date Info: day of week, day of year, ISO week number, leap year status, days in month
- Business days: excludes weekends from day counts
- Smart overflow: adding 1 month to Jan 31 gives Feb 28/29 (not March)
- Private: runs entirely in the browser — no data transmitted