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How to use the calculator
Time and time zones
Network reference time is estimated from this site's edge response and is shown with round-trip latency. Choose the city or time zone to use for calculation. For cross-zone intervals, choose a separate end time zone.
Date difference
Calendar days compare civil date labels. Elapsed hours compare real instants in the selected time zones, including daylight-saving changes.
Calendar addition
Days, months, and years use calendar arithmetic in the selected time zone. Hours and minutes are elapsed time. Thirty days and one month are deliberately different operations.
Business deadlines
Add mode excludes the starting date. Count mode excludes the start and includes the end. The selected holiday calendar controls weekends, public holidays, and adjusted workdays.
Something looks wrong?
Send the exact inputs, expected result, language, time zones, and device to [email protected]
Worked examples
Date difference
2026-09-01 to 2026-09-11 is 10 calendar days, or 11 when the end date is included.
Try this exampleAdd a month
2026-01-31 plus one month is 2026-02-28; plus 30 days is 2026-03-02.
Try this exampleBusiness days
With weekends only, Friday 2026-09-04 plus one business day is Monday 2026-09-07. A regional holiday may change that result.
Try this exampleCalendar export preserves the calculated time and time zone. Calendar dates and time-off ranges export as all-day events. Times repeated or skipped during daylight-saving transitions require a different input or an unambiguous UTC time.
Holiday sources and coverage
Language, time zone and holiday calendar are separate choices. US federal holidays are not every state or employer holiday; Canada CRA closures are not a nationwide provincial calendar. Published data can change. Check the source before relying on a deadline.
| Calendar | Supported dates | Data retrieved | Source |
|---|---|---|---|
| Weekends only | 1900-01-01 – 2099-12-31Weekends only; no public holidays | — | — |
| United States · Federal | 2021-01-01 – 2099-12-31Rule-based, not a published future schedule | — | Source |
| China · Mainland | 2024-01-01 – 2026-12-31Published data | 2026-09-04 | Source |
| Japan | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| Taiwan | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| South Korea | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| UK · England and Wales | 2019-01-01 – 2028-12-31Published data | 2026-10-12 | Source |
| UK · Scotland | 2019-01-01 – 2028-12-31Published data | 2026-10-12 | Source |
| UK · Northern Ireland | 2019-01-01 – 2028-12-31Published data | 2026-10-12 | Source |
| Canada · CRA closures | 2026-01-01 – 2026-12-31Published data | 2026-10-12 | Source |
| Australia · ACT | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| Australia · New South Wales | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| Australia · Northern Territory | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| Australia · Queensland | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| Australia · South Australia | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| Australia · Tasmania | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| Australia · Victoria | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| Australia · Western Australia | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |
| New Zealand · National | 2026-01-01 – 2027-12-31Published data | 2026-10-12 | Source |