The ISM Band That Quietly Runs the World
In 1947, at the ITU's Atlantic City conference, the world's spectrum regulators set aside frequency bands for Industrial, Scientific, and Medical equipment — bands where devices could transmit without individual licenses, subject to power limits. One of those bands, 2,400-2,500 MHz, was intended for microwave ovens (which heat food at 2,450 MHz) and industrial heating. Nobody in 1947 predicted that half a century later, this same "junk" spectrum would carry Wi-Fi, Bluetooth, Zigbee, and a thousand other unlicensed devices.
Today, the 2.4 GHz band is the most crowded spectrum in existence. A single apartment building might have hundreds of Wi-Fi routers, dozens of Bluetooth devices, and a few microwave ovens all radiating in the same 2,400-2,483.5 MHz range. The regulatory documents write it in MHz; the marketing materials say GHz. Both are the same frequencies, and the conversion between them — divide by 1,000 — is the number this page exists to make automatic.
GHz = MHz ÷ 1,000
because 1 GHz = 10⁹ Hz and 1 MHz = 10⁶ Hz
The factor 1,000 is exact — a definition, not a measurement.
From 2.4 GHz to 5 GHz to Millimeter Wave
The wireless ladder keeps climbing. Wi-Fi's second major band, 5 GHz, spans 5,150-5,875 MHz — 5.15-5.875 GHz. 5G cellular adds bands at 3.5 GHz (3,500 MHz), 28 GHz (28,000 MHz), and beyond — the "millimeter wave" region, so called because the wavelength at 30 GHz is about 10 mm. Every step is an exact power of ten from the megahertz numbers in the regulatory tables. A network engineer configuring a 5.18 GHz channel is working with 5,180 MHz; the RF engineer measuring it thinks in gigahertz; the compliance document cites hertz. Same signal, three notations, one exact conversion chain.
Common Megahertz to Gigahertz Conversions
| MHz | GHz | Where you'd see this |
|---|---|---|
| 1 MHz | 0.001 GHz | The definitional anchor — one megahertz. |
| 100 MHz | 0.1 GHz | FM broadcast top. Old CPU clocks. |
| 700 MHz | 0.7 GHz | UHF TV band. 4G LTE low band. |
| 900 MHz | 0.9 GHz | GSM cellular band. Cordless phones. |
| 1,000 MHz | 1 GHz | The MHz-to-GHz boundary itself. |
| 2,400 MHz | 2.4 GHz | Wi-Fi, Bluetooth, microwave ovens — the ISM band. |
| 3,500 MHz | 3.5 GHz | 5G mid-band cellular. |
| 5,180 MHz | 5.18 GHz | Wi-Fi 5 GHz channel 36. |
| 5,875 MHz | 5.875 GHz | Top of the Wi-Fi 5 GHz band. |
| 24,000 MHz | 24 GHz | Automotive radar band. |
| 28,000 MHz | 28 GHz | 5G millimeter-wave band. |
| 60,000 MHz | 60 GHz | WiGig / unlicensed mmWave band. |
Worked Examples
The Wi-Fi channel frequency
Wi-Fi channel 36 on the 5 GHz band centers at 5,180 MHz. In GHz: 5,180 ÷ 1,000 = 5.18 GHz. The router's configuration page and the spectrum analyzer agree on the same channel once both use the same notation. This exact conversion underlies every channel planning spreadsheet, every interference report, and every Wi-Fi site survey.
The 5G spectrum auction
A telecom operator bids on 100 MHz of spectrum centered at 3,500 MHz — the "3.5 GHz band." The auction documents write the block as "3,400-3,500 MHz"; the press release says "3.5 GHz 5G." Both describe the same allocation, and the conversion between them (divide by 1,000) is what lets the marketing team and the engineering team discuss the same asset without confusion. The 100 MHz block is 0.1 GHz wide — another exact conversion.
The CPU clock cross-check
A CPU's spec sheet says base clock 3.5 GHz, boost 5.0 GHz. The motherboard's UEFI displays frequencies in MHz: 3,500 and 5,000. An overclocking session moving from 4,800 to 4,900 MHz is moving from 4.8 to 4.9 GHz. The conversion is exact and trivial — but misreading 5.0 GHz as 5,000 MHz when the board shows MHz would be a 1,000× error, so the mental ×1,000/÷1,000 fluency matters even in consumer hardware.
Engineering Context
The GHz range is where wireless engineering and computing converge. ITU band designations put UHF at 300 MHz-3 GHz and SHF at 3-30 GHz; the 3 GHz boundary is also where many test instruments switch their frequency reference conventions. IEEE 802.11 (Wi-Fi), 3GPP (cellular), and Bluetooth SIG standards all publish channel plans in MHz with GHz used in marketing and high-level engineering. The GHz to MHz page covers the reverse direction, and for the data rates these bands carry — 5 GHz Wi-Fi at 1 Gbps, 5G at multi-Gbps — the data storage hub has the Mbps/Gbps converters.
More: GHz to MHz · kHz to MHz · MHz to kHz · Frequency Guide
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Frequently Asked Questions
Is 2.4 GHz the same as 2,400 MHz?
Yes, exactly. 2.4 GHz = 2,400 MHz = 2,400,000,000 Hz. The GHz form is a marketing and consumer convenience; the MHz form appears in regulatory documents and engineering tables; the Hz form is what the physics runs on. All three describe the identical frequency, and the conversions between them are exact powers of ten.
Why do microwaves and Wi-Fi use the same band?
Because the 2.4 GHz ISM band was set aside for unlicensed industrial, scientific, and medical equipment — and microwave ovens (2,450 MHz) were the original high-power occupant. Wi-Fi arrived decades later as a low-power, license-exempt user of the same band. That's why a running microwave can interfere with Wi-Fi: they're sharing spectrum by design, separated only by power limits and duty cycles. The band's range is 2,400-2,500 MHz (2.4-2.5 GHz).
How do I convert GHz back to MHz?
Multiply by 1,000. 2.4 GHz = 2,400 MHz. 5.18 GHz = 5,180 MHz. 28 GHz = 28,000 MHz. The GHz to MHz page does this direction with the same exact factor, and both directions are pure decimal-point shifts — no approximation anywhere in the frequency family.