Advanced date and time calculationsElapsed time with zones, clock differences, averages, sorting and interval splitting.
Details of the first result
Dates & time
How it works
A time zone is a set of rules, not a permanent UTC offset. America/New_York changes offset seasonally; Asia/Kathmandu uses a 45-minute offset. A local clock reading can correspond to zero, one or two instants.
What you can do
Convert local date-times between IANA time zones and resolve skipped or repeated daylight-saving times explicitly.
How to use it
- Enter local YYYY-MM-DDTHH:mm:ss and choose the source and destination zones. Calculate. If the source time is skipped or repeated, keep reject to inspect the two interpretations, or deliberately choose earlier/later.
- Filter source and destination by country or territory, then explicitly choose an IANA city/zone on each side. A country can contain several zones; the country filter alone never determines an offset.
- Check the result and its notes. Copy or download only after calculating; any edit clears the old result.
Errors and limits
Zone names use the browser’s time-zone database. No country-to-one-zone guessing or network lookup is used. Historical and future results depend on installed rules. Earlier/later can move a nonexistent wall time; always inspect the resolved source.
All input stays in this tab. TXT files must be UTF-8; bulk input is limited to 200,000 characters and 10,000 lines.
Frequently asked questions
Why can 01:30 happen twice?
When clocks move back, part of the local hour repeats. In New York on Nov3 2024, 01:30 can mean UTC05:30 at −04:00 or UTC06:30 at −05:00. The default rejects this ambiguity instead of silently choosing one.
Are my dates uploaded or saved?
No. These calculations run in your browser. Inputs are not added to the address, stored between visits or sent to a server. Copy and download save only when you ask.