Date & Time Calculator
Perform common date and time arithmetic by adding a duration to a starting date and time.
Calculator
Results
How it works
Perform common date and time arithmetic by adding a duration to a starting date and time.
Example
| Example | Result |
|---|---|
| Jan 15, 2026 10:30 + 2d 5h 30m | Jan 17, 2026 16:00. |
Important notes
- Calendar calculations use Gregorian calendar rules.
- Business-day calculations exclude Saturday and Sunday unless stated otherwise.
- Time-zone calculations depend on the browser's IANA time-zone data.
- For planning purposes, verify dates and times when a contractual or legal deadline is involved.
Frequently Asked Questions
Does this convert time zones?
No. It performs arithmetic in the browser’s local time context.
How to use this calculator
What to enter
Enter or select the following as requested: Starting date & time; Days to add; Hours to add; Minutes to add. Follow the units, valid ranges, examples, and options displayed beside each field.
What the result means
The date or duration result is calculated from the entered dates, times, calendar rules, and exclusions. Check inclusive versus exclusive counting, time zone, daylight-saving changes, and whether weekends or holidays are excluded.
When to use it
Use this to plan a date, measure elapsed time, or estimate a deadline. Verify the relevant calendar, location, and legal or workplace rules when they affect the answer.