Frequency Converter

Type a number, pick the unit you're holding, and this frequency converter shows it in all eight units at once: hertz, kilohertz, megahertz, gigahertz, terahertz, RPM, radians per second, and beats per minute. There's no "convert to" box and no button to press. One value in, every unit out, live as you type. It opens on 1 GHz so the whole spread is sitting there before you touch anything.

Now, most frequency converters online only walk the Hz to GHz ladder, and that ladder is the easy part. Every rung is times a thousand, kHz to Hz, MHz to kHz, you can do it in your head. The two conversions that actually trip people are the ones those tools leave out. Radians per second, which carries a 2π and quietly eats half the wrong answers in any signals or circuits class. And RPM, a plain divide-by-60 that throws you off by a factor of 3,600 the moment you run it backwards. Both live in this table, right next to the ordinary hertz ladder, so the error-prone units sit where you can check them.

Everything runs in your browser. Nothing you type is uploaded, and it keeps converting even with no connection.

1. Type your value. A whole number, a decimal, or scientific notation like 2.4e9, all read fine.
2. Pick the unit you have in the From dropdown. That's the only unit you set. The tool works out the rest.
3. Read the table. Every unit shows your number at once, and the row for the unit you picked is shaded so you don't lose it in the list.
4. Copy any answer with the copy button on its row. No highlighting and retyping a fifteen-digit result.
5. Hit "Copy shareable link" to hand someone the exact conversion. The link reopens the tool with your value and unit already filled in.

This is the conversion the tool exists for, and the one people get wrong most. There are two honest ways to say how fast a cycle repeats, and they differ by a factor of 2π.

Ordinary frequency, plain hertz, counts whole cycles per second. One hertz is one full cycle.

Angular frequency, written ω (omega) and measured in radians per second, counts the same repetition as an angle instead of a whole turn. One cycle is one trip around a circle, and a circle is 2π radians of angle. So the angular number is bigger than the plain one by exactly that 2π:

ω = 2π × f

So 1 hertz works out at about 6.283 rad/s. Run it the other way and 1 rad/s is about 0.159 Hz, which is just 1 divided by 2π. Two units for one idea, because the math is cleaner in each spot. Anything with a sine in it (waves, oscillators, AC circuits) wants an angle, so the equations get written in ω. But nobody measures in radians, a scope or a spec sheet reports cycles per second, so the answer has to come back out in hertz. The 2π converts between the two, and it's the single most common slip in the whole subject. Drop it or double it and your answer is off by 6.28, which is just wrong enough to look plausible on the page. Let the table carry the 2π instead of your memory.

RPM (revolutions per minute) and BPM (beats per minute) are both frequencies counted over a minute instead of a second. A minute holds 60 seconds, so you divide by 60 to reach hertz and multiply by 60 to go back. That gives you clean anchors: 60 RPM is exactly 1 Hz, one turn a second, and 120 BPM is 2 Hz.

The trap is the direction. Get the divide-by-60 backwards, multiply when you should divide, and a motor spec is suddenly off by a factor of 3,600. That's the kind of error that survives a review, because 3,600 of something still looks like a real number. A car engine idling at 900 RPM is turning at 15 Hz, and a machine tool at 3,000 RPM lands on exactly 50 Hz. Motor people and machinists cross this line all day, because the spec sheet reads in RPM while a vibration analyzer or a variable-frequency drive reads in hertz, and the drive is literally setting an electrical frequency in Hz to hold a shaft speed in RPM.

One caveat the units can't cover for you. The conversion assumes one revolution equals one cycle, which is true for a spinning shaft but not for, say, a four-stroke engine that fires once every two crankshaft turns. The arithmetic is right either way, the mechanical meaning is on you.

BPM rides the same divide-by-60. A house track at 128 BPM is about 2.13 Hz, a resting heart rate of 60 BPM is 1 Hz. It rarely needs converting for music on its own, but the moment you sync a tempo to a delay or an LFO measured in hertz, the beat and the effect have to land in the same units. That's what the BPM row is for.

The metric side of the table is for when a number is simply too long to read. Each step up is another factor of a thousand:

• kHz (thousand): AM radio, a "1010 AM" station is 1010 kHz, plus audio sample rates like 44.1 kHz.
• MHz (million): FM radio at 88 to 108, TV broadcast bands, older CPU clocks.
• GHz (billion): WiFi's 2.4 and 5 GHz bands, Bluetooth, a modern "3.6 GHz" processor, a microwave oven at 2.45 GHz.
• THz (trillion): infrared light and lab spectroscopy, past the point where everyday electronics live.

Say "2.4 gig" and you mean 2.4 GHz, which is 2,400,000,000 plain hertz, and the tool spells out every zero the instant you type it. If two neighboring units ever look off by exactly a thousand, you've slipped a rung.