Hours to Milliseconds (h to ms)
1 hour equals 3,600,000 milliseconds exactly.
How to convert hours to milliseconds
To convert hours to milliseconds, multiply the number of hours by 3,600,000. This factor is exact. To go the other way, multiply milliseconds by 2.777777778×10⁻⁷ (rounded).
milliseconds = hours × 3,600,000
Example: 10 hours = 36,000,000 milliseconds.
Months and years are not constant. This site uses the average Gregorian year of 365.2425 days, so one 'year' converts to 365.2425 days, not 365; use 'common year' for exactly 365 days.
About these units
Hour (h)
60 minutes or 3,600 seconds, one twenty-fourth of a mean solar day.
Egyptian astronomers gave us the twelve. Coffin lids from about 2150 BC show the night divided into exactly 12 intervals, tied to the rising of star groups called decans, and the day was later split into 12 hours with sundials. These were seasonal hours, a twelfth of the daylight, so a summer hour was longer than a winter one. The word itself comes from Greek hora, originally any span of time, through Latin and Old French into English in the 13th century.
Equal hours of 1/24 of a day were probably first proposed by Hipparchus, and mechanical clocks made them the practical choice, since a clock showing seasonal hours had to be readjusted every morning and evening. Today the hour is exactly 3,600 seconds and is a non-SI unit accepted for use with the SI. Civil time still bends it a little: UTC hours have lasted 3,601 seconds 27 times since 1972 to keep clocks within 0.9 seconds of the Earth's rotation. In practice we use it for working shifts, travel times and electricity bills measured in kilowatt-hours.
1 hour = 3,600 seconds (exactly).
Sources: Wikipedia: Hour; BIPM: SI Brochure, 9th edition
Millisecond (ms)
One thousandth of a second. Used for computer response times and sports timing.
Milliseconds sit on the border between what people perceive and what instruments must be built to catch. Nobody feels a single one: a human blink lasts roughly 100 to 400 of them, and the average resting heart cycle is about 860. The prefix milli- makes the unit exactly one thousandth of a second, so it is a handy yardstick for events a little too quick to notice but slow enough for a stopwatch-style instrument to capture.
A millisecond is one thousandth of a second, and the scale references are easy to picture. Light in a vacuum covers about 300 km in 1 ms, and sound in air covers about 34 cm. A film frame at 24 frames per second lasts about 41.7 ms, one cycle of 60 Hz mains power lasts about 16.7 ms, and a camera shutter set to 1/125 s is open for about 8 ms. Online gamers watch network latency in milliseconds, with typical broadband figures of 5 to 80 ms, and telephone engineers recommend keeping one-way delay under about 150 ms before conversation starts to feel awkward.
1 millisecond = 0.001 seconds (exactly).
Sources: Wikipedia: Millisecond; BIPM: SI Brochure, 9th edition
Related conversions
- Milliseconds to hours (reverse)
- Hours to seconds
- Hours to minutes
- Hours to days
- Hours to weeks
- Hours to months
- Hours to years
- Hours to microseconds
- Hours to nanoseconds
- Hours to decades
- Hours to centuries
- Hours to millennia
- Hours to picoseconds
- Seconds to milliseconds
- Minutes to milliseconds
- Days to milliseconds
- Weeks to milliseconds
- Months to milliseconds
- Years to milliseconds
- Microseconds to milliseconds
- Nanoseconds to milliseconds
- Decades to milliseconds
- Centuries to milliseconds
- Millennia to milliseconds
See all time units.