The Band Plan That Made the Prefixes Famous
Radio spectrum is divided into bands, and each band inherited the prefix that made its numbers readable. The AM broadcast band — 530 to 1,700 kHz — was assigned in the 1930s, when receivers tuned by clicking through kilocycles (the old name for kHz). FM — 88 to 108 MHz — was assigned later, in the 1940s, on frequencies a hundred times higher, where megahertz was the natural notation. Both bands coexist on the same dial today, and switching between them means multiplying or dividing by 1,000 — the exact relationship this page automates.
The prefixes themselves are SI definitions, fixed in 1960: kilo- = 10³, mega- = 10⁶, giga- = 10⁹. There is no measurement uncertainty in any conversion between them. A station at 640 kHz is at 0.64 MHz, exactly, to every digit. The radio engineer who designs a filter for "640 kHz" and the datasheet that says "0.64 MHz" are discussing the identical frequency, and this converter proves it in one input.
MHz = kHz ÷ 1,000
because 1 MHz = 10⁶ Hz and 1 kHz = 10³ Hz
The ratio is exactly 1,000 — a definition, not a measurement.
Shortwave and the kHz/MHz Borderlands
The region right above 1 MHz is where both notations coexist. Shortwave broadcasters — the international radio services that bounce signals off the ionosphere — operate between roughly 3 and 30 MHz. An international station on 12.1 MHz is also "12,100 kHz." Ham radio operators are fluent in both, because their equipment displays frequencies in kHz or MHz depending on the band and the radio's firmware. The conversion is exact and constant: divide by 1,000, or multiply by 1,000, whichever direction you're crossing.
Common Kilohertz to Megahertz Conversions
| kHz | MHz | Where you'd see this |
|---|---|---|
| 1 kHz | 0.001 MHz | The definitional anchor — one kilohertz. |
| 530 kHz | 0.53 MHz | Bottom of the AM broadcast band. |
| 640 kHz | 0.64 MHz | A classic AM station frequency. |
| 1,000 kHz | 1 MHz | The kilohertz-to-megahertz boundary itself. |
| 1,700 kHz | 1.7 MHz | Top of the AM broadcast band. |
| 3,000 kHz | 3 MHz | Bottom of the shortwave (HF) band. |
| 7,000 kHz | 7 MHz | The 40-meter ham radio band. |
| 12,100 kHz | 12.1 MHz | A typical shortwave international station. |
| 30,000 kHz | 30 MHz | Top of HF, start of VHF. |
| 88,000 kHz | 88 MHz | Bottom of the FM broadcast band. |
| 100,000 kHz | 100 MHz | Mid-FM band. A typical local station. |
| 108,000 kHz | 108 MHz | Top of the FM broadcast band. |
Worked Examples
The AM antenna design
An engineer designs an antenna for an AM station at 640 kHz. Wavelength: 300,000,000 m/s ÷ 640,000 Hz = 468.75 m. The engineer might also write the calculation in MHz: 300 ÷ 0.64 = 468.75 m (using the c-in-Mm/s shortcut). Both routes give the same answer because 640 kHz = 0.64 MHz exactly. The wavelength formula works in either notation as long as the speed of light matches the units — and the conversion between the notations is this page's job.
The receiver's band switch
A software-defined radio displays frequencies in kHz on the AM band and MHz on the FM band. You tune a shortwave station reported as "12,100 kHz" but the display shows MHz below 30 MHz: 12,100 ÷ 1,000 = 12.1 MHz. The station is exactly where you expected. The reverse — a friend gives you "7.0 MHz" and your display is in kHz: 7 × 1,000 = 7,000 kHz. Same frequency, two notations, one exact conversion.
The microcontroller's clock
A 16 MHz microcontroller's datasheet gives the CPU clock as 16 MHz. A timing calculation needs hertz: 16 × 1,000,000 = 16,000,000 Hz, or in kHz: 16,000 kHz. The step from MHz to kHz is ×1,000; from MHz to Hz it's ×1,000,000. Both are exact. The embedded engineer does this chain so often it becomes automatic — and this converter makes it automatic for everyone else.
Engineering Context
Radio frequency bands are defined by ITU regulations in hertz, and the prefixes are pure SI: VLF (3-30 kHz), LF (30-300 kHz), MF (300 kHz-3 MHz), HF (3-30 MHz), VHF (30-300 MHz), UHF (300 MHz-3 GHz). Every band boundary is a power-of-ten step, which makes the kHz↔MHz conversion exact at every crossing. For the next step up the ladder — MHz to GHz — see the MHz to GHz converter. For the data rates carried on these bands — a 6 MHz TV channel carrying 19.4 Mbps of ATSC data — see the data storage hub.
More: MHz to kHz · Hz to kHz · kHz to Hz · Frequency Guide
Related Unit Converters
Frequently Asked Questions
Is 1 MHz bigger than 1 kHz?
Yes — 1 MHz = 1,000 kHz = 1,000,000 Hz. A megahertz is exactly one thousand kilohertz. The prefix ladder is kilo (10³), mega (10⁶), giga (10⁹), and each rung is a factor of 1,000 above the last. So 1 MHz is a thousand times 1 kHz, and a billion times 1 Hz.
Why do European and US AM bands differ in kHz?
The AM broadcast band spacing differs by regulation: US stations are on 10 kHz spacings (530, 540, 550…), while European AM uses 9 kHz spacing (531, 540, 549…). Both are measured in kHz, and both convert to MHz identically (531 kHz = 0.531 MHz). The spacing difference is a historical regulatory choice, not a unit difference — the hertz is the same everywhere, which is the point of having an international unit.
How do I convert MHz to kHz?
Multiply by 1,000. 88 MHz = 88,000 kHz. 2.4 GHz = 2,400,000 kHz. The MHz to kHz page on this site handles that direction, and both directions are exact powers of ten — there's no approximation anywhere in the frequency family.