# How does Wi-Fi carry data on radio waves?

> Same kind of radio wave as your microwave oven, at a tiny fraction of the power. The trick is how many bits it packs into every wiggle.

https://learnfold.app/wait-how/how-wi-fi-works/ · Updated 2026-11-02

Wi-Fi is an ordinary radio wave, close in frequency to the one inside your microwave oven. It carries data by changing the wave in small, agreed ways. Each short slice of wave is shifted in timing and set to a certain height, and each allowed shape stands for a group of bits. Wi-Fi also splits its channel into dozens of thin lanes and changes every lane at once, and newer Wi-Fi sends separate streams from several antennas. The wave itself hasn't changed in decades. What changed is how many bits go into each wiggle.

## The same radio waves as your microwave, far weaker

HyperPhysics, a physics reference from Georgia State University, says modern microwave ovens run at 2,450 MHz. US rules set aside 2,450 MHz, plus or minus 50 MHz, for industrial, scientific and medical equipment, which is 2,400 to 2,500 MHz. Wi-Fi's 2.4 GHz band runs from 2,400 to 2,483.5 MHz, so it sits inside the oven's band. The Wi-Fi Alliance lists two more bands, 5 GHz and 6 GHz.

The power is a different story. Under ETSI's European standard, a 2.4 GHz Wi-Fi radio may radiate at most 100 milliwatts. Ovens in a US Department of Energy test sample were rated from 700 to 1,300 watts, so the oven is roughly 7,000 to 13,000 times stronger, and the oven's metal screen keeps its microwaves from getting out into the room. US rules let Wi-Fi feed up to 1 watt into its antenna, which narrows the gap but still leaves the oven hundreds of times stronger.

So the wave is nothing special. Everything clever is in how it's shaped.

## First, switch the wave on and off

The oldest way to send a message by radio is to switch the wave on and off, like Morse code. The ITU's Morse rules make a dash three dots long, with one dot of silence inside a letter and seven between words. At 20 words a minute, a quick operator's pace, each dot lasts 60 milliseconds by morsecode.world's timing formula. That's about 17 on or off moments a second.

Wi-Fi's radio versions never worked like this, even in 1997. It's the baseline, one bit per moment at best, and the moments are slow.

## Better, bend the wave

The first Wi-Fi standard, IEEE 802.11 from 1997, kept the wave on and nudged its timing instead. The IEEE working group's page says one of its radio versions ran at 1 Mbit/s using two timings, a technique called binary phase shift keying. It reached 2 Mbit/s with four timings, quadrature phase shift keying. Four timings means each slice of wave, called a symbol, carries 2 bits.

Change the wave's height as well as its timing and you get more shapes per symbol. Engineers call this QAM. Sixteen shapes carry 4 bits, 64 shapes carry 6, and Cisco notes that Wi-Fi 6 uses 1,024 shapes for 10 bits and Wi-Fi 7 uses 4,096 for 12.

Finer shapes are harder to tell apart. Cisco's white paper on 802.11n says its highest rates need a very clean signal and a nominal range of less than 20 feet.

## Split the channel into thin lanes

Rather than change one wave faster, 802.11a and 802.11g split each 20 MHz channel into 52 narrow lanes called subcarriers, 312.5 kHz apart. Keysight's overview lists 48 lanes for data and 4 for keeping in sync. Every lane sends a new symbol every 4 microseconds, all at the same time. This is OFDM.

The arithmetic for their top speed is in Cisco's paper. With 64 shapes, each of the 48 lanes carries 6 bits, so one symbol carries 288 bits. A quarter of those are error correction, which leaves 216 bits of data every 4 microseconds. That's 54 Mbit/s.

Try it. Pick a way to shape the wave, add lanes and antennas, and watch the bits per tick add up.

Start on 4 timings, then switch to 64 shapes and watch the wave's height start to vary too. Then pick 48 lanes. The single wave is now one of 48, each carrying its own 6 bits every tick.

Wi-Fi 6 packs its lanes tighter. A Rohde & Schwarz white paper on 802.11ax says it divides every 20 MHz into 256 lanes, 78.125 kHz apart, with each symbol lasting four times longer.

## Add antennas and send separate streams

The last trick reuses the same lanes. 802.11n, from 2009, can send up to four separate streams at once on the same frequencies, each from its own antenna. Cisco's paper says this works because of reflections. Metal surfaces, pipes and beams bounce the signal around like mirrors, so each stream reaches each receiving antenna along slightly different paths. The receiver compares what its antennas heard and works out the separate streams with "a lot of complex math".

There's a catch. Cisco's paper says S streams need at least S antennas at both ends. A phone with two antennas can take two streams at most, however many the router has. With four streams in a 40 MHz channel, 802.11n's top rate was 600 Mbit/s.

## On paper versus your living room

Put all four tricks together, with wider channels, and the numbers on the box get big. Intel gives 9.6 Gbps as Wi-Fi 6's maximum throughput, then adds that real networks "may not reach this top speed".

Real speeds are lower for reasons that follow from everything above. The finest shapes need a strong signal at close range. Cisco's paper notes that at the highest rates, the fixed overhead of each transmission "can be longer than the entire data frame", and devices lose more time taking turns and colliding. The FCC adds that sharing a network with other devices, or living near other networks, can slow things down. A wall between you and the router weakens the signal, and the finest shapes are the first to become unreadable.

It's still a plain radio wave. Wi-Fi just learned to bend it in more ways, on more lanes, from more antennas at once.

## From radio waves to web pages

Wi-Fi only covers the last few metres. The next questions are where the bits go after your router and how a page finds its way back. Learnfold's course How the internet actually works follows a single page load, from [opening a page](/learn/internet/open-a-page/) to [how DNS finds a server](/learn/internet/dns/). And if you like stories about radio signals and timing, [How GPS works](/wait-how/how-gps-works/) is one. Each lesson ends with follow-up questions, so a [curiosity rabbit hole](/use-cases/follow-your-curiosity-rabbit-hole/) can keep going. Building a course from your own question is part of Learnfold's paid subscription. It's an AI tutor and can make mistakes, so check anything important against sources like the ones below.

Lesson on this in Learnfold: https://learnfold.app/learn/internet/

## Quick answers

**Does Wi-Fi use the same frequency as a microwave oven?**

Close to it. Ovens run at 2,450 MHz, and 2.4 GHz Wi-Fi uses 2,400 to 2,483.5 MHz, inside the band US rules set aside for industrial, scientific and medical equipment around 2,450 MHz. Wi-Fi also uses 5 and 6 GHz. The power is very different. A 2.4 GHz Wi-Fi radio in Europe may radiate at most 100 milliwatts, while ovens in a US Department of Energy test sample were rated 700 to 1,300 watts.

**How does Wi-Fi turn a radio wave into ones and zeros?**

It changes the wave in small, agreed ways. Each short slice of wave, called a symbol, is shifted in timing and set to a certain height. Both ends know the list of allowed shapes, and each shape stands for a group of bits. With 64 shapes, one symbol carries 6 bits.

**What are OFDM and MIMO?**

OFDM splits a Wi-Fi channel into many narrow lanes, called subcarriers, and sends a symbol on every lane at once. 802.11a and g use 48 data lanes in a 20 MHz channel. MIMO uses several antennas at each end to send separate streams at the same time. The receiver uses its own antennas to tell the streams apart.

**Why is my Wi-Fi slower than the speed on the box?**

Box speeds are theoretical peaks. Intel gives 9.6 Gbps as Wi-Fi 6's maximum and says real networks may not reach it. The top rates need a strong signal at short range, every transmission carries overhead, and devices take turns sharing the air with each other and with neighbouring networks.

## Sources

1. [Microwave Ovens, by R. Nave (HyperPhysics)](https://hyperphysics.gsu.edu/hbase/Waves/mwoven.html), Georgia State University
2. [47 CFR 18.301, Operating frequencies (industrial, scientific and medical equipment)](https://www.law.cornell.edu/cfr/text/47/18.301), Cornell Law School Legal Information Institute
3. [47 CFR 15.247, Operation within the bands 902-928 MHz, 2400-2483.5 MHz, and 5725-5850 MHz](https://www.law.cornell.edu/cfr/text/47/15.247), Cornell Law School Legal Information Institute
4. [ETSI EN 300 328 V2.2.2, Wideband transmission systems operating in the 2,4 GHz band](https://www.etsi.org/deliver/etsi_en/300300_300399/300328/02.02.02_60/en_300328v020202p.pdf), ETSI
5. [Microwave ovens technical support document, chapter 5, Engineering analysis](https://www1.eere.energy.gov/buildings/appliance_standards/pdfs/mwo_snopr_ch5_engineering.pdf), US Department of Energy
6. [Wi-Fi (MAC/PHY)](https://www.wi-fi.org/wi-fi-macphy), Wi-Fi Alliance
7. [802.11 timelines](https://www.ieee802.org/11/Reports/802.11_Timelines.htm), IEEE 802.11 Working Group
8. [IEEE P802.11 main general info page](https://www.ieee802.org/11/main.html), IEEE 802.11 Working Group
9. [Recommendation ITU-R M.1677-1, International Morse code](https://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC-M.1677-1-200910-I!!PDF-E.pdf), International Telecommunication Union
10. [Morse code timing](https://morsecode.world/international/timing/), morsecode.world
11. [802.11 OFDM overview](https://helpfiles.keysight.com/csg/89600B/Webhelp/Subsystems/wlan-ofdm/content/ofdm_80211-overview.htm), Keysight
12. [802.11n: The Standard Revealed (white paper, 2009)](https://community.cisco.com/legacyfs/online/legacy/1/1/3/68311-white_paper_c11-427843_v1.pdf), Cisco
13. [Wi-Fi 7 and the growing future of wireless design guide](https://www.cisco.com/c/en/us/products/collateral/networking/wireless/wifi7-future-of-wireless-dg.html), Cisco
14. [IEEE 802.11ax Technology Introduction (white paper), by L. Ward](https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/premiumdownloads/premium_dl_brochures_and_datasheets/premium_dl_whitepaper/IEEE-802-11ax-Technology-Introduction_wp_3609-9470-52_v0100.pdf), Rohde & Schwarz
15. [What is Wi-Fi 6?](https://www.intel.com/content/www/us/en/gaming/resources/wifi-6.html), Intel
16. [Home network tips for the coronavirus pandemic](https://docs.fcc.gov/public/attachments/DOC-363362A1.pdf), Federal Communications Commission