Fixed-duration conversion starts with the second
The second is the SI base unit of time. CalcOS converts each supported duration through seconds, retaining the exact decimal or integer relationship until the result is displayed.
Minutes, hours, days, and weeks in this converter are fixed elapsed-time quantities. Civil-clock adjustments and calendar arithmetic are separate problems.
Supported time-unit definitions
| Unit | Exact relationship | Typical use |
|---|---|---|
| nanosecond | 10⁻⁹ s | electronics and computing |
| microsecond | 10⁻⁶ s | instrumentation and latency |
| millisecond | 10⁻³ s | timing and response measurement |
| minute | 60 s | short everyday durations |
| hour | 3,600 s | work and travel durations |
| day | 86,400 s | fixed elapsed duration |
| week | 604,800 s | seven-day elapsed duration |
Why months and years are excluded
A calendar month can contain 28, 29, 30, or 31 days, and a civil year can contain 365 or 366 days. Their elapsed duration depends on dates and calendar rules, so CalcOS does not silently assign either one a fixed number of seconds.
Elapsed time is not civil time
This converter handles numerical durations. It does not calculate time zones, daylight-saving transitions, leap-second events, dates, or deadlines; those require contextual inputs rather than a constant multiplier.
Authoritative references: BIPM SI Brochure for the SI second and accepted units of time, and NIST Handbook 44, Appendix C for US measurement tables.