1 GHz to MHz

1 gigahertz is 1,000 megahertz

One gigahertz is 1,000 megahertz, and that ratio does not change with the device or the reading. Giga means one billion, or 10 to the 9th. Mega means one million, or 10 to the 6th. Divide a billion by a million and the answer is 1,000, so a frequency in gigahertz is the same frequency in megahertz cut into groups of a thousand.

Both prefixes come from the metric system. The NIST table of SI prefixes lists giga as 10⁹ and mega as 10⁶, and the BIPM SI Brochure defines them the same way. They are powers of ten, so nothing here is rounded and nothing depends on the size of the number you start with.

Read the ladder one rung at a time. A kilohertz is 1,000 hertz. A megahertz is 1,000 kilohertz, which is 1,000,000 hertz. A gigahertz is 1,000 megahertz, which is 1,000,000 kilohertz. Each step up multiplies by 1,000 and each step down divides by 1,000, so the arithmetic stays the same at every rung.

Written out, 1 GHz is 1,000,000,000 Hz. That is one billion complete cycles in one second, each one starting and finishing in a billionth of a second. The number is large, and the physical event it counts is tiny.

The formula, run in both directions

Gigahertz to megahertz is one multiplication: MHz = GHz x 1,000. Megahertz back to gigahertz is one division: GHz = MHz / 1,000. There is no offset to add and no fraction to carry, which is why the answer survives a quick mental check.

Work three cases. A 2.4 GHz router channel is 2.4 x 1,000 = 2,400 MHz. A 5.8 GHz cordless phone is 5.8 x 1,000 = 5,800 MHz. A 0.9 GHz cellular band is 0.9 x 1,000 = 900 MHz. Decimals move three places to the right, so 2.412 GHz becomes 2,412 MHz, the center of Wi-Fi channel 1 in the 2.4 GHz band.

Run the same numbers back. 985 MHz / 1,000 = 0.985 GHz. 2,450 MHz / 1,000 = 2.45 GHz, the oven figure. 5,150 MHz / 1,000 = 5.15 GHz, the bottom edge of the 5 GHz Wi-Fi band. Multiply any answer by 1,000 and the starting value returns.

The most common slip is the decimal direction. A megahertz number is always larger than the gigahertz number it came from, because the megahertz is the smaller unit. If a conversion turns 2,400 MHz into 2.4 GHz and then into 0.0024 GHz, the second step divided a number that was already in the smaller unit.

What the 2.4 GHz and 5 GHz router labels cover

The number on a router box names a band, not a single frequency. In the United States the 2.4 GHz band runs from 2,400 MHz to 2,483.5 MHz, a strip 83.5 MHz wide. The 5 GHz band runs from 5,150 MHz to 5,850 MHz, a strip 700 MHz wide. The newer 6 GHz band runs from 5,925 MHz to 7,125 MHz. The FCC pages on Wi-Fi spectrum list the same edges.

A channel inside a band is also measured in megahertz, and that number is a width rather than a position. A 20 MHz channel carries data across 20 MHz of spectrum. A 40 MHz channel is twice as wide, an 80 MHz channel is four times as wide, and a 160 MHz channel is eight times as wide. The 2.4 GHz band is narrow enough that only three 20 MHz channels avoid overlapping, which is why apartment buildings with a dozen networks slow down on that band.

Wider channels carry more data per second, so the 5 GHz and 6 GHz bands usually feel faster. That advantage comes from the width of the channel and the lower noise floor, not from the size of the number in the product name. A 5,000 MHz signal is not ten times more capable than a 500 MHz signal just because the number is larger.

Signal range runs the other way. Higher frequencies lose energy faster as they travel and pass through walls less easily, so the 2.4 GHz band generally reaches farther from the router than the 5 GHz band, even though its channel is narrower. That trade is why most home routers broadcast both bands and let the device choose.

A 3.5 GHz processor counts 3.5 billion steps a second

A processor rated at 3.5 GHz runs at 3,500 MHz. Each clock cycle lasts 1 / 3,500,000,000 of a second, which is 0.2857 nanoseconds, or 285.7 picoseconds. At 5 GHz a cycle lasts 0.2 nanoseconds. The number moves in the opposite direction from the cycle time: double the gigahertz and you halve the time between steps.

Gigahertz measures how often a circuit switches, not how much work it finishes in a second. Two chips rated at 3.5 GHz can differ by a wide margin, because one may complete more instructions per cycle, or hold more of its data in a fast cache. Comparing clock speeds only makes sense inside one processor family and one generation.

The same arithmetic covers memory and graphics clocks, which are often quoted in megahertz instead. A graphics card at 1,750 MHz is 1.75 GHz, and its cycle lasts 0.5714 nanoseconds. A memory clock at 6,000 MHz is 6 GHz. Convert both to the same unit before you compare them, or the smaller number will look slower than it is.

Microwaves, phones and the 2.45 GHz slot

A microwave oven is the appliance that puts a gigahertz number on the label. Most models cook at 2.45 GHz, which is 2,450 MHz, inside a band set aside for industrial, scientific and medical use. Water, fat and sugar in food absorb energy at that frequency far better than the surrounding air does, which is why the inside of the oven heats while the air stays cool. The FDA page on microwave oven radiation describes the same operating band and the leakage limits that apply to a home unit.

Because 2,450 MHz sits inside the 2.4 GHz Wi-Fi band, a worn door seal on an old oven can put enough energy into the room to slow a nearby network while the oven runs. The two devices share a slice of spectrum rather than a protocol, so one cannot ask the other to wait.

Other household radios land on nearby rungs. Bluetooth hops around 2,400 to 2,483.5 MHz, the same strip as Wi-Fi. A 1.9 GHz cordless phone is 1,900 MHz. A 5.8 GHz phone is 5,800 MHz, above the main 5 GHz Wi-Fi channels. A baby monitor sold as 2.4 GHz is 2,400 MHz. The gigahertz label on the box is a shortcut for the band, and the megahertz figure tells you exactly where inside it the device works.

Cell towers sit higher up. A 3.7 GHz 5G site is 3,700 MHz, and a 28 GHz millimeter wave site is 28,000 MHz. The higher band carries more data across a wider channel but travels a shorter distance and loses signal at a window or a leaf, which is why carriers mix low, middle and high bands in one market.

MHz, Mbps and the 1,024 that does not belong here

Frequency and speed are different quantities that share a few letters. Megahertz counts cycles per second in a signal. Megabits per second counts data moved per second through a connection. A 5 GHz Wi-Fi link does not deliver 5,000 Mbps, and a 1 Gbps fiber plan does not run at 1 GHz. The first number describes where on the dial the radio operates, and the second describes how much information it carries on that spot.

The 1,024 factor belongs to computer memory, where a kilobyte was once 1,024 bytes. Frequency prefixes are always powers of ten, so 1 GHz is exactly 1,000 MHz and never 1,024 MHz. A page that reports 1,024 MHz for a gigahertz has borrowed a rule from a different corner of computing.

Router model names add their own confusion. A name like AC1200 adds the throughput of each band, for example 300 Mbps on 2.4 GHz plus 867 Mbps on 5 GHz, and rounds the total. The 1200 is a data rate in megabits per second, not a frequency in megahertz, and the two labels on the same box describe unrelated measurements.

One more unit sits between the two. A channel width of 160 MHz is 0.16 GHz of spectrum, so a single wide channel occupies a sixth of a gigahertz. When a review says a router uses a 160 MHz channel, it means width, while a 5 GHz band label means position. Both are written in megahertz, and they answer different questions.

Common bands, in gigahertz and in megahertz

The table lists frequencies people ask about by name, with each one written both ways. The gigahertz column is the megahertz column divided by 1,000, so the two columns carry the same information at different scales.

Use the table as a sense check. If a conversion produces 24 MHz for a 2.4 GHz router, the decimal moved the wrong way, because the true figure is 2,400 MHz. If a cordless phone at 5.8 GHz turns into 5,800,000 MHz, the multiplication ran twice. The correct answer sits between the two columns of the table, and a glance is usually enough to catch the error.

A last check costs nothing: take the megahertz answer, divide by 1,000, and confirm that the gigahertz value you started with comes back. Then compare the size of the two numbers. The megahertz figure is larger by exactly three decimal places, never by two and never by four.

For a wider view of how frequency, period and wavelength relate, the NIST time and frequency division keeps the reference material behind the units used on this page.