| Microseconds (µs) | Centiseconds (cs) |
|---|---|
| 1 Microsecond | 0.0001 cs |
| 2 Microseconds | 0.0002 cs |
| 3 Microseconds | 0.0003 cs |
| 4 Microseconds | 0.0004 cs |
| 5 Microseconds | 0.0005 cs |
| 10 Microseconds | 0.001 cs |
| 20 Microseconds | 0.002 cs |
| 25 Microseconds | 0.0025 cs |
| 50 Microseconds | 0.005 cs |
| 100 Microseconds | 0.01 cs |
| Reference | Microseconds (µs) | Centiseconds (cs) |
|---|---|---|
| A blink of an eye | 100000 µs | 10 cs |
| One heartbeat at rest | 830000 µs | 83 cs |
| Half of a football match | 2.7 × 109 µs | 270000 cs |
| A full day | 8.64 × 1010 µs | 8640000 cs |
The microsecond is a unit of time equal to one millionth of a second, or one thousandth of a millisecond. Its symbol is µs, written with the Greek letter mu, and the form us appears where that character is inconvenient to type.
It sits below the threshold of human experience entirely. Nothing a person does or perceives happens on this scale, so the unit belongs wholly to instruments. Light travels about three hundred metres in a microsecond, roughly the length of three football pitches, which sets a hard floor on how fast any signal can cross a room, a circuit board or a continent.
Satellite navigation depends on measuring it accurately. A receiver works out its position from the arrival times of signals from several satellites, and an error of one microsecond in that timing translates into a position error of about three hundred metres. This is why the satellites carry atomic clocks and why the system corrects for relativistic effects: the clocks in orbit run measurably faster than clocks on the ground, by about thirty-eight microseconds a day, and without that correction navigation would drift by kilometres within hours.
Electronics works comfortably at this scale. The switching time of a power transistor, the pulse width in radar, the interval between samples in high-speed data acquisition and the response of an analogue-to-digital converter are all quoted in microseconds. A microcontroller running at one megahertz completes one instruction cycle per microsecond, which makes the unit the natural currency of embedded timing.
Physics and chemistry use it for processes that are fast but not extreme. Muons produced in the upper atmosphere have a mean lifetime of about 2.2 microseconds, and the fact that they reach the ground at all is a direct experimental demonstration of time dilation. Some fluorescence decays, gas-phase reactions and shock-wave phenomena also occupy this range.
Audio engineering encounters it in digital sampling. At the standard rate of 44,100 samples per second, one sample lasts about 22.7 microseconds, and the timing jitter that degrades converter performance is measured in fractions of that.
One microsecond equals 0.000001 seconds, 0.001 milliseconds, or 1000 nanoseconds.
The centisecond is a unit of time equal to one hundredth of a second. Its symbol is cs. The name is almost never spoken, but the quantity it describes is one of the most familiar in the world, because it is the resolution at which competitive sport reports its results.
Swimming, athletics, cycling, rowing and speed skating all publish times to the hundredth of a second. The choice is not arbitrary. Electronic timing can resolve far finer intervals, but the physical uncertainties of the events themselves make finer figures meaningless. In swimming, the tolerance permitted on the length of a pool lane is such that two lanes may differ by enough to matter at the thousandth of a second, which is why the sport declines to separate swimmers below the hundredth and awards shared medals instead.
Athletics reaches the same conclusion by a different route. Sprint times are recorded to the thousandth internally but published to the hundredth, rounded upward so that no athlete is credited with a time faster than they ran. The rule means a hand-timed result and an electronically timed one are not comparable, and world records require full automatic timing precisely because the difference between the two is several centiseconds.
Outside sport the unit appears mostly in disguise. Video at fifty frames a second advances one frame every two centiseconds, and the perceptual threshold at which a delay begins to feel like lag in an interactive system sits around ten centiseconds. Industrial control loops and programmable logic controllers often run on cycle times in this range, fast enough to keep up with machinery and slow enough to be computationally cheap.
The name itself is unusual because the SI prefix centi is rarely applied to the second. Milli and micro are far more common, and where a hundredth of a second is needed people usually say exactly that rather than reaching for a prefixed name.
Photography meets the quantity in shutter speeds around a hundredth, which is roughly the slowest a steady hand can hold a standard lens without visible blur.
One centisecond equals 0.01 seconds, 10 milliseconds, or 10,000 microseconds.