1 MHz to kHz

One megahertz is 1,000 kilohertz, so the decimal point moves three places

One megahertz is 1,000 kilohertz, and one kilohertz is 1,000 hertz. Read the two steps together and 1 MHz is 1,000,000 Hz, or 0.001 GHz. The table runs the same pattern from a thousandth of a megahertz up to a thousand of them.

Every row follows one multiplication: 1 x 1000 = 1,000 and 1,000 x 1000 = 1,000,000. The digits you type stay in place while the decimal point slides right by three, which is why 2.4 MHz becomes 2,400 kHz without a calculator and without rounding.

The same signal has a length in time as well as a count in hertz. At 1 MHz one full cycle lasts 1 microsecond, so a thousand cycles fill 1 millisecond, and that period is often the more useful number when you are reading a timing diagram instead of a dial.

The ratio comes from the prefixes: k is 10^3 and M is 10^6

The factor of 1,000 is not a property of radio. It falls out of the SI prefix table, where kilo means 10 to the 3 and mega means 10 to the 6 for any unit you attach them to. The BIPM SI Brochure, 9th edition (2019), prints both prefixes in its table of SI prefixes, and the ratio is the difference of the exponents: 10^6 / 10^3 = 1,000.

Because the prefixes are definitions, the conversion is exact. There is no measured constant hidden in it and no tolerance to quote. A converter that returned anything other than 1,000 kHz for 1 MHz would be broken rather than approximate. Giga is 10 to the 9 on the same table, so a gigahertz is 1,000 megahertz and a megahertz is 0.001 gigahertz; tera is 10 to the 12, which puts 1 MHz at 0.000001 THz.

Case carries real meaning in that table. Prefix symbols are case sensitive: the kilo symbol is a lowercase k, so 1 kHz is correct and 1 KHz is not, while M means 10 to the 6 and m means 10 to the minus 3. A specification written as 1 mHz is a millihertz offset in a stability figure, not a one-megahertz clock, and 1,000,000 / 0.001 = 1,000,000,000 separates the two by nine orders of magnitude.

A second slip is binary thinking applied to a decimal prefix. 1024 kHz is 1.024 MHz, not 1 MHz: the difference is 24 kHz, and 24 / 1000 = 2.4 percent high. That number comes from memory sizes, where 1024 is a power of two, and it has no place in a frequency conversion built on powers of ten. Both slips are caught by one question: did the number grow or shrink by exactly three digits? Megahertz to kilohertz always grows by three, kilohertz to megahertz always shrinks by three, and a jump of ten digits means the wrong prefix came along.

Four values through the division, and three on the way back

Multiplication covers megahertz to kilohertz. Take a 0.5 MHz signal and scale it: 0.5 x 1000 = 500 kHz. Do the same with three more values that show up in real equipment: 2.4 x 1000 = 2,400 kHz, 10.7 x 1000 = 10,700 kHz, and 27 x 1000 = 27,000 kHz.

The reverse direction divides. A receiver tuned to 455 kHz sits at 455 / 1000 = 0.455 MHz, the familiar intermediate frequency of a superheterodyne radio. A dial at 915 kHz, in the license-free band used by utility meters and short-range links, reads 915 / 1000 = 0.915 MHz. An FM station at 88,100 kHz is 88,100 / 1000 = 88.1 MHz.

The direction check is easy to apply without thinking about it. Kilohertz numbers are the large ones, so any frequency that reads in the hundreds of thousands belongs in kHz or Hz, while the same signal in MHz reads in the tens or hundreds. A dial that shows 100,000 for an FM station is quoting kilohertz.

Period: 1 MHz is 1 microsecond, 1 kHz is 1 millisecond

Frequency and period are reciprocal, so the conversion runs in the opposite direction from the one above. The period is one divided by the frequency in hertz: 1 / 1,000,000 = 0.000001 s, which is 1 microsecond. At the other end of the same ladder, 1 / 1,000 = 0.001 s, which is 1 millisecond.

Nanoseconds are the working unit for anything fast. One microsecond holds 1,000 nanoseconds, and one millisecond holds 1,000,000. A 16 MHz clock has a period of 1 / 16 = 0.0625 µs, or 62.5 ns, which is the shortest interval a single cycle of that part can represent.

The pattern in the third column is the one to memorize. Move up by a factor of 1,000 in frequency and the period drops by the same factor, so each row of the table is a shift of three decimal places in both directions. Two rows agree to the digit: 1,000,000 ns at 1 kHz and 1000 ns at 1 MHz, a factor of 1,000 in both columns.

The FCC bands written in kHz: AM 535 to 1705, FM 88,000 to 108,000

Broadcast bands are where kilohertz and megahertz meet in ordinary life, and the boundaries are set in regulation rather than convention. The FCC rules at 47 CFR 73.14, as published in the eCFR (2026 edition), define the AM broadcast band as 535 to 1705 kHz. The same subpart lists 117 AM carrier frequencies, starting at 540 kHz and stepping in 10 kHz increments to 1700 kHz.

Section 73.201 defines the FM band as 88 to 108 MHz, divided into 100 channels of 200 kHz each, with carriers from 88.1 MHz to 107.9 MHz. Written in kilohertz, that band runs from 88,000 to 108,000 kHz, and the channel spacing is 200 kHz, or 0.2 MHz.

The band edges convert both ways without effort. 535 x 1000 = 535,000 Hz puts the bottom of the AM dial at 0.535 MHz, and 1705 / 1000 = 1.705 MHz puts the top just under 1.71 MHz. On the FM side, 88 x 1000 = 88,000 kHz and 108 x 1000 = 108,000 kHz, so a station at 101.5 MHz occupies 101,500 kHz of the dial and its 200 kHz channel spans 101,400 to 101,600 kHz.

The AM channel count follows from the spacing: 1700 - 540 = 1160 kHz of tuning range, and 1160 / 10 = 116 steps, which gives 117 carriers once both ends are counted. The FM count works the same way: 107.9 - 88.1 = 19.8 MHz, and 19.8 / 0.2 = 99 steps, so 100 channels.

Clock rates: 1 MHz costs 1,000 ns per cycle, 16 MHz costs 62.5 ns

Microcontroller datasheets quote a clock in megahertz and a timing diagram in nanoseconds, so the two columns have to be converted in your head. At 1 MHz the clock ticks once every 1,000 ns. At 8 MHz the interval is 1 / 8 = 0.125 µs, or 125 ns. At 16 MHz it halves again to 62.5 ns, and at 48 MHz it is 1 / 48 = 0.0208 µs, or 20.83 ns.

The second column is a division and the third is a multiplication, and they are checks on each other. A 16 MHz part fits 16 x 1000 = 16,000 cycles into a millisecond, and each of those cycles is 1000 / 16 = 62.5 ns long. An instruction that takes four cycles at 16 MHz therefore needs 4 x 62.5 = 250 ns, which is 0.25 µs.

Frequency counters turn the same arithmetic into resolution. A counter with a 1 s gate counts 1,000,000 cycles at 1 MHz and resolves 1 Hz, while a 0.1 s gate counts 100,000 cycles and resolves 1 / 0.1 = 10 Hz. A 10 ms gate resolves 100 Hz, which is why bench meters let you trade measurement time for digits.

Sampling: 1 kHz takes a sample every millisecond, 48 kHz every 20.83 µs

Audio converters are specified in kilohertz and their timing in microseconds, so the same factor of 1,000 shows up in a different costume. A 1 kHz sample rate means one sample every 1 ms. An 8 kHz rate, the classic telephone figure, means 125 µs between samples, and 44.1 kHz gives 1,000,000 / 44,100 = 22.6757 µs. A 48 kHz rate is 1,000,000 / 48,000 = 20.8333 µs.

The rate in kilohertz and the rate in hertz differ by the usual 1,000: 44.1 x 1000 = 44,100 samples per second, and 48 x 1000 = 48,000. The Nyquist column is half the sample rate, so a 48 kHz system can represent tones up to 24 kHz, and a 44.1 kHz system stops at 22.05 kHz.

Mixing the units is the common error here. A file labelled 48 kHz described in a report as 48,000 kHz would be a thousand times too fast, and the period would read 0.0208 ns instead of 20.83 µs. The sample period is a good sanity check on any stated rate: real audio rates sit between 10 µs and 1 ms per sample, and nothing in that range needs a nanojoule of doubt.

Wavelength at 1 MHz: 299.79 m, from c = 299,792,458 m/s

A frequency also fixes a wavelength, and the constant that connects them is exact. The speed of light in vacuum is 299,792,458 m/s by definition, a value fixed by the BIPM and repeated in the 9th edition of the SI Brochure (2019). Divide it by the frequency in hertz and the wavelength falls out in meters.

At 1 MHz the sum is 299,792,458 / 1,000,000 = 299.7925 m, which is a bit under 300 m and close to 984 ft. At 1 kHz the same constant gives 299,792.458 m, or 299.79 km. At 100 MHz it is 2.9979 m, and at 2.4 GHz it is 0.1249 m, or 12.49 cm.

The 1 MHz row is the one worth remembering, because 300 m is easy to hold in your head and easy to scale. Double the frequency and halve the wavelength, so 2 MHz is about 150 m and 4 MHz about 75 m. The AM band sits between roughly 176 m and 560 m, which is why AM antennas are tall, and the FM band sits near 3 m, which is why a quarter wave whip is about 75 cm.