The tiny and huge numbers behind Wi-Fi, turned into things you can hold, see and picture.
Keith Parsons ยท CWNE #3
October 2026
Start here
The short answer
Wi-Fi runs on numbers that are too small or too big to picture. This guide turns a few of them into things you already know: a foot of wire, a stack of money, a ruler.
You don't need to do any math. Each page gives you one picture to keep.
A few wordsA nanosecond is a billionth of a second. A millisecond is a thousandth of a second. A watt measures power, like on a light bulb. Wi-Fi uses a tiny slice of one.
What's inside
A nanosecond you can hold3
Wi-Fi keeps time in tiny steps5
Near and far6
Power: the rule of 3s and 10s7
Why distance costs so much9
How big is a radio wave?10
Bits and bytes11
Four things people get wrong12
Where these facts come from13
Scales and Ratios, Explained2
Time
A nanosecond you can hold
Grace Hopper was a computer pioneer and a US Navy admiral. She used to hand out pieces of wire about 30 cm (1 foot) long.
Each piece showed how far light, or a radio wave, travels in one nanosecond. That's one billionth of a second. Fast, but not instant.
Figure 1. A nanosecond, as a length. Light travels about a foot in a billionth of a second. The drawing is not actual size.
Grace Hopper
"I had to point out that between here and the satellite were a very large number of nanoseconds."
Lecture at MIT Lincoln Laboratory, 1985.
Scales and Ratios, Explained3
Time
An admiral had asked her why satellite messages took so long. Her answer was distance. A satellite is a long way up, and every foot of the trip takes time.
Figure 2. A long trip is a lot of nanoseconds. Lay Hopper's wires end to end up to a satellite, and each one adds a nanosecond. Not to scale.
Scales and Ratios, Explained4
Time
Wi-Fi keeps time in tiny steps
Wi-Fi devices take turns to talk. Each turn is timed in millionths of a second.
Your access point also sends out a short "here I am" message, called a beacon. It sends about ten of them every second.
That gap between beacons feels like nothing to you. For light, it's a long trip.
Figure 3. In the time between two beacons, light could travel past a GPS satellite. The lime gap on top and the lime bar below are the same moment. Drawn to a normal, ruler-style scale.
Scales and Ratios, Explained5
Distance
Near and far
Your Wi-Fi signal crosses a room. A GPS signal falls from high in space. Both travel at the speed of light.
The access point on your ceiling is a few meters away. A Starlink satellite is about 480 km (300 miles) up. A GPS satellite is much farther again.
Figure 4. Three distances, three zoom levels. No single drawing can show all three to one scale. Each panel has its own scale bar.
That's why GPS signals arrive so weak. They have come a long way.
Scales and Ratios, Explained6
Power
Power: the rule of 3s and 10s
Wi-Fi engineers measure signal strength in decibels, or dB. You only need two facts.
Add 3 dB and the power about doubles. Add 10 dB and it's ten times bigger. Going down works the same way. Think of it as money:
Figure 5. Decibels as money, starting from $100. Add 3 dB and your money about doubles. Add 10 dB and it grows ten times.
Scales and Ratios, Explained7
Power
A billion to one
Your phone sends its Wi-Fi signal with up to about a tenth of a watt. By the time it reaches the access point across the house, it can be a billion times weaker.
That sounds broken, but it's normal. A billion to one is like one second out of about 32 years. Wi-Fi radios are built to hear signals that faint.
Figure 6. Weak on arrival is normal. The signal thins out with every wall and every foot. The bar below shows how big a billion to one is.
Scales and Ratios, Explained8
Distance and size
Why distance costs so much
A signal spreads out as it travels, like paint from a spray can. The farther it goes, the thinner it gets.
Figure 7. The same power, spread over more area. Double the distance and the signal covers four times the area. Each spot gets a quarter as much.
Scales and Ratios, Explained9
Distance and size
How big is a radio wave?
Wi-Fi waves are small enough to hold. A 2.4 GHz wave is about 12 cm (5 inches) long; the figure shows it at actual size. A 5 or 6 GHz wave is about 5 to 6 cm (2 inches) long.
Figure 8. One wave from each Wi-Fi band. The bands with smaller waves have more room for data, but they fade faster through walls.
Scales and Ratios, Explained10
Data
Bits and bytes
Internet speed is sold in megabits. File sizes are counted in megabytes. They are not the same thing.
A byte is eight bits. So to turn a speed in Mbps into megabytes each second, divide by 8.
Figure 9. Eight bits fill one byte. Pour a second of a 100 Mbps plan into byte jars and you fill about 12 of them.
Figure 10. Why a download takes longer than you think. A 100 Mbps plan moves a movie in minutes, not seconds. Drawn to a normal, ruler-style scale.
Real downloads are slower still. Other devices share the connection, and every message carries a little extra.
Scales and Ratios, Explained11
Straight facts
Four things people get wrong
Each myth is followed by what's true.
MythA nanosecond is too short to matter.
FactLight only goes about a foot in one. Wi-Fi times its turns in millionths of a second, so nanoseconds add up fast.
MythAdding 3 dB doubles the power exactly.
FactIt's close to double. That's close enough for any Wi-Fi math you'll ever do.
MythA 100 Mbps plan downloads 100 megabytes a second.
FactMbps means megabits. Divide by 8. At best, that's about 12 megabytes a second.
MythA weak signal means something is broken.
FactA signal can arrive a billion times weaker than it left and still work. Wi-Fi is built for that.
Pictures to keep
Figure 11. Four pictures to keep. The four ideas from this guide worth remembering.
Scales and Ratios, Explained12
Sources
Where these facts come from
Gathered 28 September 2026.
NIST SP 330, The International System of Units (SI): the speed of light and the metric prefixes
Grace Hopper, lecture at MIT Lincoln Laboratory, 25 April 1985, transcript published by Speakola
Smithsonian National Museum of American History, object record for Hopper's nanosecond wires
CWNP, "802.11 Beacon Intervals", quoting IEEE 802.11 (the beacon interval)
GPS.gov, Space Segment (GPS satellite height); Starlink Space Safety, "Constellation altitudes" (about 480 km)
HyperPhysics, Georgia State University, Inverse square law
IEC, Prefixes for binary multiples; FCC, Broadband Speed Guide
About this guideWritten for anyone who wants Wi-Fi's numbers to mean something. Companion guides: How GPS Works, Explained; Analog vs Digital, Explained; Starlink, Explained. Keith Parsons, CWNE #3, Wireless LAN Professionals.
