Microsecond to Millisecond
Free instant microsecond to millisecond converter. 1 μs = 0.001 ms.
Common Microsecond to Millisecond values
| Microsecond (μs) | Millisecond (ms) |
|---|---|
| 1 | 0.001 |
| 5 | 0.005 |
| 10 | 0.01 |
| 25 | 0.025 |
| 50 | 0.05 |
| 100 | 0.1 |
| 500 | 0.5 |
| 1000 | 1 |
Measuring + conversion tools
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How does Microsecond to Millisecond conversion work?
Type a value in the Microsecond (μs) field and the equivalent in Millisecond (ms) appears instantly to the right. The math uses the exact formula shown above — no rounding errors, no approximations beyond standard floating-point precision. Use the swap button to flip the units and see the inverse conversion.
Microsecond. One millionth of a second. Used in electronics and high-precision timing.
Millisecond. One thousandth of a second. Common in computing and human-reaction-time measurement.
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Conversion factors come from the official standard (NIST, BIPM, ISO definitions where applicable). Values are precise to standard floating-point limits.
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How it works — the formula
1 minute = 60 s
1 hour = 3,600 s
1 day = 86,400 s
1 Julian year = 365.25 d = 31,557,600 s
1 Gregorian year ≈ 365.2425 d ≈ 31,556,952 sThe second is the SI base unit, defined since 1967 by the caesium-133 hyperfine transition (9,192,631,770 cycles per second, exactly). Minutes, hours, and days are exact multiples of seconds. The "year" is ambiguous — astronomers use the Julian year (365.25 d) while civil calendars follow the Gregorian (365.2425 d on average); the IAU 2015 declared 1 Julian year = 31,557,600 s exactly, which is what this calculator uses.
Worked examples
- Inputs:
- 1 day = ? s
- Output:
- 24 × 3600 = 86,400 s exactly
- Inputs:
- 1 Julian year vs Gregorian
- Output:
- Julian = 31,557,600 s; Gregorian = 31,556,952 s — differs by 648 s/year
- Inputs:
- 1,000,000,000 s ≈ ?
- Output:
- ~31.7 Julian years (the famed "billion seconds birthday")
Limitations
- Months are not exact: 28, 29, 30, or 31 days depending on calendar position; this calculator uses the average (30.436875 d) for month conversion.
- Leap seconds (UT1↔UTC) are 1-second corrections occasionally added to UTC; civil time conversions ignore them.
- "Year" is ambiguous — Julian, Gregorian, sidereal (~365.2564 d), tropical (~365.2422 d) — pick the one your domain expects.
- Computer epoch times (Unix, Windows FILETIME) use distinct origins and resolutions; convert via dedicated libraries for exact accuracy.
Time conversions are exact rational arithmetic when both units are exact multiples of the second; calendar-aware conversions (months, years) carry the calendar's own approximation.