Time Converter.
Convert between picoseconds, nanoseconds, milliseconds, seconds, minutes, hours, days, weeks, months, years, and more. Click a reference duration to load it directly.
Precision
How many significant digits to display in results.
Number Format
Always show exponential form (e.g. 3.6e+3 s). Enabled automatically for very large or very small values.
Unit Reference
Month — uses 30.4375 days (1/12 of the 365.25-day Julian year).
Year — Julian year: exactly 365.25 days = 31,557,600 s.
Decade / Century — 10× and 100× the Julian year respectively.
Fortnight — exactly 14 days, common in UK and Australian payroll.
Unit Reference
Sub-second Units
A millisecond (ms) is 10⁻³ s — the latency threshold for perceived UI responsiveness. A microsecond (µs) is 10⁻⁶ s — the budget for database queries and CPU context switches. A nanosecond (ns) is 10⁻⁹ s — L1 cache hits take ~1–4 ns. A picosecond (ps) is 10⁻¹² s — light travels about 0.3 mm in 1 ps.
Seconds, Minutes & Hours
The second is the SI base unit of time, defined since 1967 as exactly 9,192,631,770 cycles of the caesium-133 hyperfine transition. A minute is exactly 60 s; an hour is exactly 3,600 s. These are the units of everyday scheduling, sports timing, and most engineering work.
Days, Weeks & Fortnights
A civil day is exactly 86,400 s. A week is 7 days (604,800 s); a fortnight is 14 days (1,209,600 s), widely used in UK and Australian payroll cycles. These are pure multiples — no daylight-saving time or leap-second corrections are applied.
Months, Years & Beyond
Calendar months vary (28–31 days), so this converter uses the mean Julian month of 30.4375 days (2,629,800 s). The Julian year is exactly 365.25 days = 31,557,600 s — also the basis for the astronomical light-year. Decades and centuries are 10× and 100× the Julian year.
How time conversion works
Every conversion routes through seconds as the canonical base unit. To convert 5 hours to minutes: 5 × 3,600 = 18,000 s ÷ 60 = 300 min. The same two-step approach handles any pair of units — from picoseconds to centuries — without accumulating floating-point error from chained conversions.
Seconds to minutes and hours
Divide seconds by 60 for minutes, or by 3,600 for hours. To go the other way, multiply: 90 min × 60 = 5,400 s. One useful anchor: 1 hour = 3,600 s = 3.6 × 10³ s.
Days, weeks, and fortnights
A day is exactly 86,400 s (24 × 3,600). A week is 604,800 s; a fortnight (14 days) is 1,209,600 s. These are exact multiples — no daylight-saving or leap-second adjustments are made.
Calendar months and years
Because calendar months range from 28 to 31 days, this converter uses the mean Julian month: 365.25 ÷ 12 = 30.4375 days = 2,629,800 s. The Julian year (365.25 days = 31,557,600 s) is exact by definition and is also the basis for the astronomical light-year.
Nanoseconds and computing
In computing, nanoseconds matter: a 3 GHz CPU completes one clock cycle every ~0.333 ns. An L1 cache hit costs ~1–4 ns; main memory access ~60–100 ns; an SSD sequential read ~50–150 µs; a network round-trip to a nearby server typically 1–50 ms. These orders of magnitude help diagnose performance bottlenecks at a glance.
Frequently Asked Questions
- How many seconds are in a year?
- Using the Julian year (365.25 days), one year = 31,557,600 seconds exactly. The common 365-day approximation gives 31,536,000 seconds. The difference is the extra quarter day that accumulates into a leap day every four years.
- How many seconds are in a day?
- Exactly 86,400 seconds (24 × 60 × 60). A week is 604,800 s; a fortnight is 1,209,600 s. These are exact civil-day multiples — no daylight-saving or leap-second adjustments are applied in this converter.
- Why does the converter use 30.4375 days for a month?
- Calendar months range from 28 to 31 days, so there is no single exact value. This converter uses the Julian mean month: 365.25 ÷ 12 = 30.4375 days. For precise date arithmetic, use a calendar library rather than unit conversion.
- How fast is a nanosecond in computing terms?
- A 3 GHz CPU completes one clock cycle every ~0.33 ns. An L1 cache hit costs ~1–4 ns; main memory access ~60–100 ns; SSD sequential read ~50–150 µs; local network round-trip ~1–50 ms. These orders of magnitude are essential for performance profiling.
Privacy & Security
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