Frequency converter: Hz, kHz, MHz, GHz, and RPM

Convert between hertz, kilohertz, megahertz, gigahertz, and RPM at ToolHQ's frequency converter, all common frequency units with instant results. Free, no account required.

Frequency measures how often a repeating event occurs per second. Audio frequencies are measured in hertz (Hz) and kilohertz (kHz). Radio and wireless signals operate in megahertz (MHz) and gigahertz (GHz). Engine and motor speeds are measured in RPM (revolutions per minute). Each field uses the unit that fits its scale.

ToolHQ's frequency converter handles all five common frequency units and returns results simultaneously, so you can compare values across fields in seconds.

Key Takeaways

• 1 kHz = 1,000 Hz; 1 MHz = 1,000 kHz; 1 GHz = 1,000 MHz
• RPM to Hz: divide RPM by 60 (3,000 RPM = 50 Hz)
• AM radio: 535-1,705 kHz; FM radio: 87.5-108 MHz; WiFi 2.4 GHz / 5 GHz
• Frequency and period are inverses: period (seconds) = 1 / frequency (Hz)
• No data is stored or transmitted, all calculations run locally in your browser

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Frequency unit overview

Frequency is measured in hertz (Hz), defined as one cycle per second. All larger units are multiples of hertz:

Unit	Abbreviation	Value	Used in
Hertz	Hz	1 cycle/second	Audio, electronics base unit
Kilohertz	kHz	1,000 Hz	AM radio, audio, ultrasound
Megahertz	MHz	1,000,000 Hz	FM radio, older CPUs, RF signals
Gigahertz	GHz	1,000,000,000 Hz	WiFi, modern CPUs, 5G, microwave
Terahertz	THz	10^12 Hz	Infrared light, spectroscopy
RPM	RPM	Revolutions per minute	Engines, motors, machinery

Converting RPM to Hz: Divide by 60. A motor running at 3,000 RPM completes 50 full rotations per second = 50 Hz.

Converting Hz to RPM: Multiply by 60. A 60 Hz electrical grid means generators rotate at 3,600 RPM (for 2-pole generators).

All calculations run locally in your browser, no data is stored or transmitted.

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Real-world frequency reference table

Application	Frequency range	Unit
Human hearing	20 Hz to 20 kHz	Hz / kHz
Bass frequencies (music)	20-250 Hz	Hz
Midrange (speech, instruments)	250 Hz to 4 kHz	Hz / kHz
Treble/high frequencies	4 kHz to 20 kHz	kHz
AM radio (US)	535-1,705 kHz	kHz
FM radio	87.5-108 MHz	MHz
Aircraft VHF communication	108-137 MHz	MHz
4G LTE networks	700 MHz to 2.7 GHz	MHz / GHz
WiFi 2.4 GHz band	2,400-2,483.5 MHz	GHz
WiFi 5 GHz band	5,150-5,850 MHz	GHz
Bluetooth	2,400-2,485 MHz	GHz
5G (sub-6 GHz)	600 MHz to 6 GHz	GHz
5G millimeter wave	24-100 GHz	GHz
Microwave oven	2.45 GHz	GHz
Modern CPU clock speeds	3-5 GHz	GHz

Practical note: When your phone says it is connected to "2.4 GHz WiFi," it means the radio signal cycles at 2,400,000,000 times per second (2.4 billion Hz). The higher frequency "5 GHz WiFi" carries more data per second but penetrates walls less effectively.

Mini-story 1: Leo was studying for his amateur radio license exam and needed to understand the frequency allocations for different radio services. The exam materials listed frequencies in MHz, but his handheld radio displayed kHz for some bands. He entered 146 MHz (a common VHF amateur frequency) into ToolHQ's frequency converter and confirmed it was 146,000 kHz. He then checked 7.1 MHz (the 40-meter HF band) and saw it was 7,100 kHz, which matched the kHz display on his radio. The converter helped him move between the two notations the exam used interchangeably.

Convert frequency units free at ToolHQ

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How to use the ToolHQ frequency converter

1. Go to the tool. Navigate to ToolHQ's frequency converter. No account or sign-up required.
2. Enter your value. Type any number in the input field.
3. Select your source unit. Choose Hz, kHz, MHz, GHz, or RPM.
4. Read all results. The converter returns the equivalent in all supported units simultaneously.

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Frequency and period: the inverse relationship

Frequency and period are mathematical inverses. If you know one, you can calculate the other:

• Period (T) = 1 / Frequency (f)
• Frequency (f) = 1 / Period (T)

Examples:

• A 60 Hz power grid: period = 1/60 = 0.0167 seconds (each AC cycle takes 16.7 milliseconds)
• A 440 Hz musical A note: period = 1/440 = 0.00227 seconds (each wave cycle takes 2.27 milliseconds)
• A 2.4 GHz WiFi signal: period = 1/2,400,000,000 = 0.000000000417 seconds (0.417 nanoseconds per cycle)

This relationship is why higher frequencies carry more information: more cycles per second means more opportunities to encode data within each unit of time.

Radians per second to Hz: Some engineering and physics contexts use radians per second (rad/s) instead of Hz. The conversion is: Hz = rad/s / (2 x pi). So 100 rad/s = 100 / 6.2832 = 15.92 Hz.

For data transfer rates (which involve related concepts of bandwidth and frequency), ToolHQ's data storage converter handles bits, bytes, kilobytes, megabytes, and gigabytes.

Mini-story 2: Nina was an electrical engineering student troubleshooting a motor control project. Her lab notes specified that a stepper motor should rotate at 600 RPM, but the motor driver required a step-pulse frequency input in Hz. She needed to know: what frequency in Hz produces 600 RPM? She entered 600 RPM into ToolHQ's frequency converter and got 10 Hz. The motor driver required a pulse at 10 Hz to produce 600 RPM. She set the output to 10 Hz and the motor ran correctly. (For stepper motors with multiple steps per revolution, the actual pulse frequency multiplies by the steps-per-revolution count, but the base unit conversion was the starting point she needed.)

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Frequently asked questions

How do I convert MHz to Hz?

Multiply by 1,000,000. Example: 100 MHz x 1,000,000 = 100,000,000 Hz. Or equivalently, 100 MHz = 100,000 kHz = 100 GHz / 1,000.

How do I convert RPM to Hz?

Divide by 60. Example: 1,200 RPM / 60 = 20 Hz. This tells you the number of full rotations per second.

What is the difference between Hz and kHz?

Kilohertz (kHz) = 1,000 hertz (Hz). Hertz is the base unit (cycles per second). Kilohertz is used when the number of cycles per second reaches into the thousands, as with audio frequencies above 1,000 Hz and AM radio signals.

Why do WiFi signals use GHz?

Higher frequency signals can carry more data per second (higher bandwidth potential). The 2.4 GHz and 5 GHz WiFi bands were chosen as unlicensed spectrum in the industrial, scientific, and medical (ISM) radio bands where interference from microwave ovens and other devices is acceptable.

Is the frequency converter free?

Yes. ToolHQ's frequency converter is completely free, with no account, no sign-up, and no usage limits.

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The short version

Frequency is cycles per second, measured in hertz. The metric prefixes scale from kHz (thousands) to MHz (millions) to GHz (billions). RPM divides by 60 to give Hz. The real-world anchor points to remember: human hearing covers 20 Hz to 20 kHz, AM radio uses kHz, FM and WiFi use MHz/GHz, and modern CPUs run at 3-5 GHz. ToolHQ's frequency converter handles all five units simultaneously, returning every equivalent from a single input. It is free, instant, and requires no account.

For related unit conversions, ToolHQ's energy converter handles joules, BTU, and kWh, and ToolHQ's unit converter covers length, weight, temperature, and more. Explore more converter tools at ToolHQ.

Convert frequency units free at ToolHQ

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