Gigahertz to kilohertz: the long way round the prefix ladder
What this conversion does
It multiplies by a million, which is two rungs of the prefix ladder travelled in one step. The result is always a long number of kilohertz, because a gigahertz is a very large number of kilohertz and no amount of rewriting changes that. The conversion is mainly a translation between instruments: a signal generator calibrated in gigahertz and a receiver logging in kilohertz are recording the same transmission.
The bands radar is assigned to
Radar allocations are named by letters rather than by units, and the letters have outlived their origins. S-band sits around 2 to 4 GHz, X-band around 8 to 12, and both names are quoted in gigahertz by everyone who works with them. The kilohertz figures for the same allocations run to seven digits, which is why the conversion is rarely written down and frequently performed by software.
Gigahertz to kilohertz conversion table
Radar and satellite allocations in both units, showing the point at which the kilohertz column stops being a number anyone would speak aloud.
| Gigahertz (GHz) | Kilohertz (kHz) |
|---|---|
| 1 | 1000000 |
| 2.4 | 2400000 |
| 2.45 | 2450000 |
| 5 | 5000000 |
| 5.8 | 5800000 |
| 24 | 24000000 |
Why one instrument still counts in kilohertz
Receiver tuning is often done with a synthesiser that steps in small, exact increments, and those increments are naturally described in kilohertz. A radar receiver can therefore be logging a signal near 9,400,000 kHz while the transmitter was specified at 9.4 GHz. Neither figure is a mistake and neither is more precise; they are two readouts of one signal, and the mismatch is a frequent source of confusion when a log is compared against a datasheet.
Two rungs, six places
From gigahertz to kilohertz the decimal point moves six places to the right, because two prefix steps of a thousand are involved. A value of 9.4 becomes 9,400,000 — seven digits, which is the signal that you have gone two rungs rather than one.
Frequently asked questions
How do I convert gigahertz to kilohertz?
Multiply by a million. So 9.4 GHz is 9,400,000 kHz, and 1 GHz is 1,000,000 kHz. The conversion crosses two prefix steps, megahertz among them, in a single multiplication.
How many kilohertz are in one gigahertz?
One million. Hertz to kilohertz is a thousand, kilohertz to megahertz another thousand, and megahertz to gigahertz a third, so from kilohertz to gigahertz the factor is a thousand squared.
Why would anyone quote a radar in kilohertz?
Usually because a receiver logs it that way. Tuning hardware steps in kilohertz-sized increments, so the readout naturally lands in that unit even when the system was designed and specified in gigahertz.
Does the converter keep all the digits?
Yes. A multiplication by a power of ten is exact, and the result is written out in full rather than being rounded or abbreviated. If the input has decimals, the output carries them too.
What is the difference between gigahertz and kilohertz for antennas?
The frequency determines the wavelength, and the antenna has to be a comparable size, so higher frequencies mean smaller antennas. That is why the same satellite service can use a dish on a roof at one frequency and a much larger dish at another.