Frequency and wavelength calculator

Type a frequency to see its wavelength, or type a wavelength to see its frequency. It also tells you which amateur band you are in.

1Type your numbersUse the white boxes. Tap an example chip if you want a starting point.
2Read the answerThe green panel updates as you type. You cannot edit it.
3See whyThe steps below show the formula with your numbers filled in.

TRY AN EXAMPLE

YOUR NUMBERS · TYPE IN THE WHITE BOXES

Frequency

MHz

Type a frequency, or type a wavelength below.

WavelengthCalculated

meters

Or type a wavelength to find the frequency.

THE ANSWER · WORKED OUT FOR YOU

Wavelength

2.048m

Wavelength in feet

6.718ft

Frequency

146.52MHz

Amateur band

2 meters

HOW IT WAS WORKED OUT

λ = 300 ÷ f

λ = 300 ÷ 146.52 MHz = 2.048 m

(300 is the speed of light in millions of meters per second, rounded the way the exams do.)

AMATEUR BANDS AT A GLANCE

Band	Frequencies (MHz)	Typical wavelength
80 / 75 meters	3.5 to 4	80 m
40 meters	7 to 7.3	42 m
30 meters	10.1 to 10.15	29.6 m
20 meters	14 to 14.35	21.2 m
17 meters	18.068 to 18.168	16.6 m
15 meters	21 to 21.45	14.1 m
12 meters	24.89 to 24.99	12 m
10 meters	28 to 29.7	10.4 m
6 meters	50 to 54	5.77 m
2 meters	144 to 148	2.05 m
1.25 meters	222 to 225	1.34 m
70 centimeters	420 to 450	0.69 m
33 centimeters	902 to 928	0.328 m
23 centimeters	1240 to 1300	0.236 m

Wavelength is shown at the middle of each band. Band edges here are the main US allocations.

What this means

A radio wave travels at the speed of light. The higher the frequency, the shorter each wave. That is why the 2 meter band is called 2 meters: waves there are about 2 meters long.

The exams use a simple shortcut: wavelength in meters equals 300 divided by the frequency in MHz. It is a rounded version of the speed of light, and it gives the answers the exam expects.

λ (meters) = 300 / f (MHz) | f (MHz) = 300 / λ (meters)

ON THE EXAM

Band names come from wavelength. If a question gives you a frequency and asks for the band, or the other way around, divide 300 by the number you have.

42 questions in the official pools involve this topic:

Common questions

Why divide by 300?

Radio waves travel at about 300 million meters per second. Dividing that by the frequency in hertz gives the wavelength in meters. Using MHz for frequency lets you write it as 300 divided by MHz.

Is the answer exact?

It is the standard exam approximation. The true speed of light is 299.79 million meters per second, so real wavelengths are a tiny bit shorter. For exams and antenna work the difference does not matter.

What is a megahertz?

One MHz is one million cycles per second. The 2 meter amateur band sits around 146 MHz, and the 20 meter band around 14 MHz.

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