Terahertz to gigahertz: the line radio stops at
What this conversion does
It multiplies by a thousand, a single step on the prefix ladder and the smallest move this tool makes. It is nevertheless the conversion that gets used most often in this part of the spectrum, because published figures for the same hardware are split between the two units: a spectroscopy paper will call a source 0.3 THz where the engineering specification calls it 300 GHz.
Two names for one boundary
The handover from electronic to optical techniques is conventionally placed at 300 GHz, which is 0.3 THz. Below it, amplifiers, mixers and waveguides work well and the language is that of radio. Above it, losses in metal rise steeply and components get small enough that manufacturing tolerances dominate, so the language shifts to that of optics. The two names refer to the same line.
Terahertz to gigahertz conversion table
Frequencies around the boundary in both notations, with the part of the spectrum each side of it belongs to.
| Terahertz (THz) | Gigahertz (GHz) |
|---|---|
| 1 | 1000 |
| 2 | 2000 |
| 10 | 10000 |
| 100 | 100000 |
| 300 | 300000 |
| 1000 | 1000000 |
Why a thousand gigahertz is a useful landmark
It gives a single number to compare against when reading two kinds of document. A radar operating at 300 GHz and a spectrometer operating at 0.3 THz are working at the same frequency, and knowing that 1000 GHz is one terahertz turns a comparison that looks like it needs a calculation into one that can be made by eye.
The easiest conversion in the tool
A thousand to one is the smallest step in the prefix ladder, so the decimal point moves only three places. A value in terahertz with three decimal places therefore becomes a gigahertz figure with no decimal places at all: 0.3 becomes 300, and 1.5 becomes 1500.
Frequently asked questions
How do I convert terahertz to gigahertz?
Multiply by a thousand. So 0.3 THz is 300 GHz, and 1 THz is 1000 GHz. It is the same relationship as megahertz to gigahertz, applied one rung further up the ladder.
Is 300 GHz the same as 0.3 THz?
Yes, identically. Which notation you meet depends on the document: radar and communications specifications tend to use gigahertz, while spectroscopy and imaging papers use terahertz for the same frequencies.
Why is 300 GHz treated as a boundary?
It is a practical rather than a fundamental limit. Above roughly that frequency, losses in metal conductors become severe, waveguides shrink to awkward dimensions, and optical methods such as lenses and mirrors become the more effective approach.
What uses frequencies just below the boundary?
High-frequency radar, some satellite links and experimental communications systems. These are built with conventional electronic components, which is why their documentation is written in gigahertz rather than terahertz.
Does the converter accept values with several decimal places?
Yes. A frequency of 0.325 THz converts to 325 GHz exactly, and longer decimals are preserved in full. Because the multiplier is a power of ten, no rounding is involved at any point.