Frequency Converter

About this Frequency Converter

The Frequency Converter changes frequencies between common SI units used in electronics, radio, computing and signal specifications. Each step is a power-of-one-thousand scale.

Frequency describes how many times something repeats per second, and it scales across an enormous range, from the roughly 60 hertz of household electrical current, to kilohertz for audio, to megahertz for radio broadcasts, to gigahertz for computer processors and wifi signals.

For related tasks, try Data Transfer Rate Converter, Data Storage Converter or Length Converter.

How the calculation works

All values are converted through hertz as the base unit using SI decimal prefixes.

How to use it

1. Enter the frequency.
2. Choose the source and target units.
3. Convert to see the equivalent.

Practical example

1 megahertz equals 1,000 kilohertz or 1,000,000 hertz.

A radio station broadcasting at 101.5 on the FM dial is actually operating at 101.5 megahertz, or 101,500,000 hertz, showing how radio frequencies use the megahertz prefix specifically to keep everyday tuning numbers manageable.

Things to double-check

A higher frequency doesn't automatically mean better or faster in every context; for audio, frequency corresponds to pitch, while for computer processors, frequency (clock speed) is only one factor among several that determine overall performance.

Hertz and its multiples

One hertz is one cycle per second. A kilohertz is 1,000 Hz, a megahertz is a million and a gigahertz is a billion. Mains electricity is 50 Hz in Pakistan, India, the UK and most of the world, and 60 Hz in the United States and a few other countries. FM radio uses roughly 88 to 108 MHz, Wi-Fi uses 2.4 and 5 GHz, and a processor running at 3.5 GHz completes 3.5 billion cycles every second. The converter keeps the powers of ten straight.

Period and wavelength

Frequency and period are inverses: the period in seconds equals one divided by the frequency. A 50 Hz supply has a period of 0.02 seconds, or 20 milliseconds. For radio and light waves, wavelength equals the speed of light divided by frequency, so a 2.4 GHz Wi-Fi signal has a wavelength of about 12.5 cm. Higher frequencies have shorter wavelengths, which is why they carry more data but are blocked more easily by walls.

Sound and rotation

Human hearing covers roughly 20 Hz to 20 kHz, with the range narrowing with age. Middle C on a piano is about 261.6 Hz, and the standard tuning note A is 440 Hz. Rotating machines can be described in hertz as well as revolutions per minute: 3,000 rpm is 50 revolutions per second, or 50 Hz. Converting between the two helps when comparing a motor with a mains frequency or a vibration.

Reading specifications

When you read a specification, check the prefix carefully: confusing MHz and GHz is a factor-of-1,000 error. A higher processor frequency does not automatically mean a faster computer, since the work done per cycle and the number of cores matter as well. For radio equipment, frequency bands are regulated, so check that equipment is allowed in your country before you use it. For precision work, note the tolerance, such as plus or minus 10 parts per million.

Audio and music

In music, doubling the frequency raises a note by an octave. The standard tuning note A4 is 440 Hz, A5 is 880 Hz and A3 is 220 Hz. Each semitone multiplies the frequency by about 1.0595, which is the twelfth root of 2. Digital audio is sampled at 44.1 kHz for CDs and 48 kHz for video, and the highest frequency that can be captured is half the sample rate, about 22 kHz and 24 kHz, which covers the range of human hearing. Frequency conversion helps when you tune instruments or set up audio software.

Wi-Fi, Bluetooth and microwaves

Many everyday devices share the 2.4 gigahertz band: Wi-Fi, Bluetooth and microwave ovens, which operate at about 2.45 gigahertz. That is why a microwave oven can interfere with a Wi-Fi signal while it is running. The 5 gigahertz band offers more channels and faster speeds but a shorter range. Mobile networks use many bands from hundreds of megahertz to several gigahertz. Knowing the unit helps you read specifications and choose the right band for your router.

Worked examples: wavelength and period

Wavelength equals the speed of light divided by the frequency. An FM station at 98.5 megahertz has a wavelength of 300,000,000 divided by 98,500,000, which is about 3.05 metres. A 5 gigahertz Wi-Fi signal has a wavelength of about 6 centimetres. Period is the reciprocal of frequency, so the note A at 440 hertz repeats every 1 over 440 seconds, which is about 2.27 milliseconds. The converter helps you move between hertz, kilohertz, megahertz and gigahertz before you apply these formulas, and a quick estimate checks that a result is reasonable.

Mains frequency and motors

Electricity is supplied at 50 hertz in much of the world, including Pakistan, and at 60 hertz in the United States and some other countries. For an alternating current motor, the synchronous speed is 120 times the frequency divided by the number of poles. A four-pole motor runs at 1,500 revolutions per minute on 50 hertz and 1,800 on 60 hertz. This is why a device built for one frequency may run too fast, too slow or hot on the other, and why travellers should check both the voltage and frequency on equipment labels before they plug it in.

The radio spectrum

Radio signals are organised by frequency. AM radio uses roughly 530 to 1,700 kilohertz, FM radio about 88 to 108 megahertz, and mobile networks, Wi-Fi and Bluetooth operate in bands from hundreds of megahertz to several gigahertz. Governments allocate the bands and set the rules for who can transmit and at what power, so equipment must be approved for the country where it is used. Some bands, such as the 2.4 gigahertz band, are open for general use but become crowded. Knowing the frequency helps you choose a router channel and understand why some signals travel farther than others.

Frequency in sound, screens and computers

Frequency appears in many other fields. Audio is sampled at 44,100 or 48,000 times a second, and the highest pitch that can be captured is half of that. Monitors refresh at 60, 120 or more times a second, and higher refresh rates look smoother. LED lamps dimmed by rapid switching can flicker at a frequency that some people notice. A processor's clock speed in gigahertz counts cycles per second, but performance also depends on the design. Whenever you see a number with hertz, ask what is repeating, and how many times a second.

Key terms explained

A hertz is one cycle per second. A kilohertz is a thousand hertz, a megahertz a million and a gigahertz a billion. The period is the time of one cycle, the reciprocal of frequency. Wavelength is the distance between peaks, and for radio waves it equals the speed of light divided by the frequency. Bandwidth in radio is the range of frequencies used. A sample rate is how many measurements are taken per second in digital audio, and refresh rate is how often a screen updates.

Rules of thumb and quick checks

To find the period, divide one by the frequency: 50 hertz repeats every 20 milliseconds. A wavelength in metres is about 300 divided by the frequency in megahertz, so a 100 megahertz signal is about 3 metres long. Human hearing spans about 20 to 20,000 hertz. Doubling the frequency raises a musical note by one octave. Check the prefix carefully, since mixing up megahertz and gigahertz is an error by a factor of a thousand.

Frequently asked questions