Degrees per hour to Revolutions per minute
°/h
rpm
Conversion History
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Quick Reference Table (Degrees per hour to Revolutions per minute)
| Degrees per hour (°/h) | Revolutions per minute (rpm) |
|---|---|
| 0.001 | 0.0000000462962962962 |
| 0.01 | 0.0000004629629629632 |
| 0.55 | 0.0000254629629629628 |
| 6 | 0.0002777777777777778 |
| 15 | 0.0006944444444444442 |
| 360 | 0.0166666666666666668 |
| 3,600 | 0.1666666666666666668 |
About Degrees per hour (°/h)
Degrees per hour (°/h) is used for very slow angular motions, particularly in navigation, geophysics, and astronomy. High-precision gyroscopes are rated by their drift in °/h — a navigation-grade ring-laser gyro may drift less than 0.01°/h, while a consumer MEMS gyro drifts hundreds of degrees per hour. Earth's rotation corresponds to 15°/h (360° ÷ 24 h), which is why the Sun appears to move 15° per hour across the sky. Telescope drive motors use this rate to compensate for Earth's rotation during long exposures.
Earth rotates at exactly 15°/h, so astronomical telescope drives track stars at 15°/h. Navigation-grade laser gyroscopes achieve drift below 0.01°/h. The Moon moves about 0.55°/h against the background stars.
About Revolutions per minute (rpm)
Revolutions per minute (RPM) measures rotational speed — how many full rotations an object completes in one minute. It is the standard unit for engine crankshaft speed, hard disk drive spindle speed, washing machine drum speed, and turntable speed. One RPM equals 1/60 Hz. Car engines idle at around 700–1,000 RPM and rev to 6,000–8,000 RPM at redline. Hard disk drives traditionally spun at 5,400 or 7,200 RPM; high-performance server drives reach 15,000 RPM. Vinyl records play at 33⅓ or 45 RPM.
A car engine idles at ~750 RPM and redlines near 6,500–8,000 RPM. A 7,200 RPM hard drive completes 120 revolutions per second. A vinyl LP plays at 33.3 RPM.
Degrees per hour – Frequently Asked Questions
How fast does the International Space Station orbit in degrees per hour?
The ISS completes one orbit (360°) in about 92 minutes, giving roughly 235°/hr — almost 16 times faster than Earth's rotation. That is why astronauts see 16 sunrises every 24 hours. At an altitude of ~408 km, the station covers about 7.66 km/s of ground track. If you could watch it from a fixed point in space, it would visibly sweep through the sky at a rate where one degree takes only about 15 seconds.
Why are gyroscope drift rates measured in degrees per hour?
Because even tiny drift accumulates into serious navigation errors over a flight or voyage. A navigation-grade ring-laser gyroscope drifts less than 0.01°/hr; over a 10-hour flight that is only 0.1° of heading error. A cheap MEMS gyro drifting 10°/hr would accumulate 100° of error in the same time — useless for navigation. Expressing drift in °/hr makes the operational impact immediately obvious to a pilot or engineer.
How do telescope mounts use the 15°/hr rate for star tracking?
Equatorial telescope mounts have a motorised right-ascension axis aligned with Earth's rotation axis. By driving that axis at exactly 15°/hr (one sidereal rate), the telescope counter-rotates against Earth's spin, keeping a star fixed in the eyepiece. Without this drive, stars would drift out of view in seconds at high magnification. Astrophotographers rely on it for long exposures without star trails.
How fast does the Moon move across the sky in degrees per hour?
The Moon's apparent motion has two components. It shares the sky's overall 15°/hr westward motion due to Earth's rotation. But it also orbits Earth, moving about 0.55°/hr eastward relative to the stars (360° ÷ 27.32 days ÷ 24 hr). The net effect: the Moon moves westward across the sky at roughly 14.5°/hr, which is why moonrise occurs about 50 minutes later each day.
Why does a Foucault pendulum appear to rotate at fewer than 15°/hr at most latitudes?
A Foucault pendulum's swing plane rotates relative to the floor at 15° × sin(latitude) per hour. At the North Pole (90°) that is the full 15°/hr; at 45° latitude it is about 10.6°/hr; at the equator it is zero. The pendulum always swings in a fixed plane in inertial space — it is the Earth rotating underneath it. The sine factor comes from the fact that only the vertical component of Earth's angular velocity vector projects into the pendulum's swing plane. Paris (48.9°N) sees about 11.3°/hr, which is why Foucault's original 1851 demonstration took most of a day to complete a visible rotation.
Revolutions per minute – Frequently Asked Questions
Why do car tachometers show RPM instead of hertz?
Because the numbers are more human-friendly. An engine idling at 750 RPM sounds reasonable; saying 12.5 Hz just feels weird for a mechanical process you can watch. RPM also maps directly to what a mechanic cares about — how many times the crankshaft turns each minute. The unit stuck from the steam-engine era when counting revolutions per minute was literally what an engineer did with a watch.
Why do hard drives spin at 5,400 or 7,200 RPM specifically?
These speeds balance data throughput against heat, vibration, and power draw. 7,200 RPM became the desktop standard because it moved the read/write head over data 33% faster than 5,400 RPM, noticeably improving access times. Server drives pushed to 10,000 and 15,000 RPM for even lower latency. Laptops favored 5,400 RPM for quieter, cooler, longer-battery operation. SSDs made the whole debate obsolete.
What RPM does a washing machine spin cycle reach?
A typical front-loading washing machine spins at 1,000–1,400 RPM during the final spin cycle, generating enough centrifugal force to squeeze water out of clothes. High-end machines hit 1,600 RPM. Top-loaders usually max out around 700–1,100 RPM. Higher spin speeds mean drier clothes out of the washer (less dryer time), but they also increase wear on fabrics and make the machine vibrate more.
How do you convert RPM to hertz?
Divide by 60. One RPM means one revolution per minute, and there are 60 seconds in a minute, so 1 RPM = 1/60 Hz ≈ 0.01667 Hz. A 7,200 RPM hard drive spins at 120 Hz; a 33⅓ RPM vinyl record rotates at about 0.556 Hz. Going the other way, multiply hertz by 60 to get RPM.
What is the highest RPM ever achieved by a man-made object?
In 2018 researchers at Purdue University spun a silica nanoparticle at over 300 billion RPM (5 GHz) using laser light in a vacuum — the fastest-spinning object ever recorded. At macroscopic scale, gas centrifuges for uranium enrichment spin at about 50,000–70,000 RPM, and dental drill turbines reach roughly 400,000 RPM. Turbomolecular vacuum pumps operate at around 90,000 RPM.