⏱️ Time & Date
Maailmankello, aikavyöhykemuunnin, päivämäärälaskuri, ajastin
Muunna aikoja kaupunkien ja aikavyöhykkeiden välillä. Ilmainen maailmankello.
Avaa työkalu →Lisää tai vähennä päiviä päivämäärästä, laske päivien määrä.
Avaa työkalu →Verkkoajastin ja sekuntikello. Aseta mikä tahansa kesto.
Avaa työkalu →Kuinka monta viikkoa vuodessa, sekuntia päivässä ja muita aikamuunnoksia.
Avaa työkalu →Time zones, date arithmetic, elapsed durations and countdowns — the calculations that are easy to get subtly wrong by hand because calendars refuse to behave arithmetically.
Time zone work in particular is worth doing with a tool. Offsets shift with daylight saving, the shift dates differ by country, and the answer you want is usually "what time is it there when it is this time here", which is two conversions rather than one.
Which tool do I want?
| If you… | Use |
|---|---|
| You are scheduling across countries | Aikavyöhykemuunnin |
| You need days between dates, or a date N days out | Päivämäärälaskuri |
| You are adding or subtracting hours and minutes | Aikalaskuri |
| You want time remaining until an event | Ajastin |
The offset is a property of the date, not the place
"New York is UTC−5" is true in January and wrong in July, when it is UTC−4. Scheduling a recurring call by fixed offset works until one side changes clocks and the other has not yet — and because the EU and US switch on different weekends, there are a couple of weeks each year when the usual gap between London and New York is off by an hour.
The reliable approach is to store the zone name rather than the offset: Europe/Oslo, not UTC+2. The zone name plus a date determines the offset; an offset alone determines nothing.
Then there are the edges. Not every zone is a whole hour off — India is UTC+5:30, Nepal UTC+5:45. Some places skip a day: when Samoa crossed the date line in 2011, 30 December simply did not exist. And on a spring-forward day one local hour never happens, so a meeting set for 02:30 that morning is a time with no instant attached to it.