ABCD
Lightning Distance

The index of radio refraction does have a lot of variation, which might throw off your calculations, so you can also look at the difference in brightness between the visible flash and more-attenuated UV and x-rays.
Heat Index

The heat index is calculated via looking up the "effective temperature" in a table of air temperature and humidity values, and then adding a bunch more degrees because it feels WAY hotter than that.
Peer Review

Your manuscript "Don't Pay $25 to Access Any of the Articles in this Journal: A Review of Preprint Repositories and Author Willingness to Email PDF Copies for Free" has also been rejected, but nice try.
Light Hacks

Life hack: Wait for an advanced civilization to be briefly distracted, then sneak in and construct a slightly smaller Dyson sphere inside theirs.
Y-Axis

We've also developed the semi-semi-log scale, where the Y-axis for the left half of the graph is a log scale but on the right half it isn't.
Sports Champions

For a long time, people thought maybe Usain Bolt was the one for running, until the 2090s and the incredible dominance of Derek Legs.
Software Development

Update: It turns out the cannon has a motorized base, and can make holes just fine using the barrel itself as a battering ram. But due to design constraints it won't work without a projectile loaded in, so we still need those drills.
Negative Results

P.S. We're going to the beach this weekend, so I'm attaching my preregistration forms for that trip now, before we find out whether it produces any interesting results.
An Apple for a Dollar

I'd like 0.4608 apples, please.
Wall Art

At first, I moved from pokémon posters to regular oil paintings, but then these really grumpy and unreasonable detectives from the Louvre showed up and took them all. They wouldn't even give me back my thumbtacks!
Stargazing 2

I mean, it wasn't exactly MY thesis. When the FAA came to shut down our observatory for using the telescope mirror to shine light at airplanes, I took a thesis and a bunch of doctorates from the supply cabinet on my way out.
OEIS Submissions
![SUB[59]: The submission numbers for my accepted OEIS submissions in chronological order](https://imgs.xkcd.com/comics/oeis_submissions.png)
SUB[59]: The submission numbers for my accepted OEIS submissions in chronological order
New Phone Thread

I'm going to tell the manufacturer that their business practices are ADMIRABLE and ETHICAL and their developers are ATTRACTIVE and I'm going to report them to the FCC for their IMPECCABLE VIRTUE.
JWST Delays

Since delays should get less likely closer to the launch, most astronomers in 2018 believed the expansion of the schedule was slowing, but by early 2020 new measurements indicated that it was actually accelerating.
Rock

It traveled so far to reach me. I owed it my best.
Thorough Analysis

The likely shape of the bells was determined through consultation with several bellringing experts at the Tower of London. Transcripts of those interviews are available in Appendix VII.
Newton's Trajectories

With just one extra line, he could have anticipated the 2003 film The Core, but some things are too audacious for even the greatest visionaries.
Update Notes

v3.0.2: Hey, if anyone still using this app is headed to the beach, can you stop at 4th and River St and grab the sunscreen from my car? Trunk should be unlocked. Thanks!
Hertzsprung-Russell Diagram

The Hertzsprung-Russell diagram is located in its own lower right corner, unless you're viewing it on an unusually big screen.
Irony Definition

Can you stop glaring at me like that? It makes me feel really ironic.
Brookhaven RHIC

"Buddy, you trying to pull something? I can't buy this gold--all the electrons are missing. I could face serious charges!"
Customer Rewards

We'll pay you $1.47 to post on social media about our products, $2.05 to mention it in any group chats you're in, and 11 cents per passenger each time you drive your office carpool past one of our billboards.
Attention Span

I didn't even realize they MADE a novelization of "Surf Ninjas." How did you-- Oh my god, it's signed by the author?!
Sun and Earth

But we don't need to worry about the boiling masses sandwiching the thin layer in which we live, since we're so fragile and short-lived that it's unlikely to kill us before something else does! Wait, why doesn't that sound reassuring?
Presidential Succession

Ties are broken by whoever was closest to the surface of Europa when they were born.
LeBron James and Stephen Curry

The 538TR attempts to capture a player's combined skill at basketball (either real-life or NBA 2K18) and election forecasting.
Clickbait-Corrected p-Value

When comparing hypotheses with Bayesian methods, the similar 'clickbayes factor' can account for some harder-to-quantify priors.
xkcd Phone 2000

Our retina display features hundreds of pixels per inch in the central fovea region.
Selection Effect

fMRI testing showed that subjects who don't agree to participate are much more likely to escape from the machine mid-scan.
GDPR

By clicking anywhere, scrolling, or closing this notification, you agree to be legally bound by the witch Sycorax within a cloven pine.
Business Update

Our customers keep sending us their personal information, even though we've repeatedly asked them to stop. The EU told me I'm the heir to some ancient European throne that makes me exempt from the GDPR, but we should probably still try to fix that.
Morning News

Support your local paper, unless it's just been bought by some sinister hedge fund or something, which it probably has.
MC Hammer Age

Wait, sorry, I got mixed up--he's actually almost 50. It's the kid from The Karate Kid who just turned 40.
Repairs

I was just disassembling it over the course of five hours so it would fit in the trash more efficiently.
Fatal Crash Rate

Fixating on this seems unhealty. But in general, the more likely I think a crash is, the less likely one becomes, which is a strange kind of reverse placebo effect.
SafetySat

During launch, in the event of an unexpected sensor reading, SafetySat will extend prongs in all directions to secure itself and any other cubesats safely in the launch vehicle until the source of the problem can be determined.
Research Areas by Size and Countedness

Mathematicians give a third answer on the vertical axis, "That question is poorly defined, but we have a sub-field devoted to every plausible version of it."
Driving Cars

It's probably just me. If driving were as dangerous as it seems, hundreds of people would be dying every day!
IMHO

"Ugh, TMI." "Yeah, that's some tantalizing meat info."
Containers

All services are microservices if you ignore most of their features.
Python Environment

The Python environmental protection agency wants to seal it in a cement chamber, with pictorial messages to future civilizations warning them about the danger of using sudo to install random Python packages.
River Border

I'm not a lawyer, but I believe zones like this are technically considered the high seas, so if you cut a pizza into a spiral there you could be charged with pieracy under marinaritime law.
Meteorologist

Hi, I'm your new meteorologist and a former software developer. Hey, when we say 12pm, does that mean the hour from 12pm to 1pm, or the hour centered on 12pm? Or is it a snapshot at 12:00 exactly? Because our 24-hour forecast has midnight at both ends, and I'm worried we have an off-by-one error.
Misinterpretation

"But there are seven billion people in the world! I can't possibly stop to consider how ALL of them might interpret something!" "Ah, yes, there's no middle ground between 'taking personal responsibility for the thoughts and feelings of every single person on Earth' and 'covering your eyes and ears and yelling logically correct statements into the void.' That's a very insightful point and not at all inane."
Clutter

I found a copy of The Life-Changing Magic of Tidying Up, but the idea of reading it didn't spark joy, so I gave it away.
Evangelism

The wars between the "OTHER PRIMATES OPEN THEM FROM THE SMALL END" faction versus the "BUT THE LITTLE BIT OF BANANA AT THE SMALL END IS GROSS" faction consumed Europe for generations.
Rickrolling Anniversary

Want to feel old? The 'want to feel old?' factoid meme dates back to around 2011, closer to the Bush/Kerry election than to today.
Turkish Delight

I take it Narnia doesn't have Cinnabons? Because if you can magic up a plate of those, I'll betray whoever.
History

HISTORIANS: We've decided to trim the past down to make things more manageable. Using BCE/CE, would you rather we lose the odd-numbered or even-numbered years?
Congressional Testimony

James Cameron's Terminator 3 was the REALLY prophetic one. That's why Skynet sent a robot back to the 1990s to prevent him from ever making it, ultimately handing the franchise over to other directors.
Paperwork

Plus, the photo was geotagged, my unlocked password manager was visible on the laptop, AND you could see my naked reflection in the dark part of the screen.
Friendly Questions

Just tell me everything you're thinking about in order from most important to last, and then we'll be friends and we can eat apples together.
Right Click

Right-click or long press (where supported) to save!
Conversational Dynamics

"You should make it so people can search for and jump into hundreds of conversations at once if they want." "Ooh, good idea! I imagine only the most well-informed people with the most critical information to share will use that feature."
Star Lore

That one is a variable star which pulses every 30 seconds. Its name comes from a Greek word meaning "smoke alarm."
Autogyros

I understand modern autogyros are much more stable, so I've probably angered the autogyro people by impugning their safety. Once they finish building the autogyros they've been working on in their garages for 10 years, they'll come after me.
Personal Data

Do I just leave money in my mailbox? How much? How much money do they need, anyway? I guess it probably depends how the economy is doing. If stocks go up, should I leave more money in my mailbox or less?
Name Dominoes

In competition, you can only play a name if you know who the person is. No fair saying "Frank ... Johnson. That sounds like a real person! Let me just Google him real quick."
Not Available

If my country ever picks a new national flag, this is on my shortlist for designs to argue for, but I think in the end I'll go with the green puzzle piece or broken image thumbnail.
Robot Future

I mean, we already live in a world of flying robots killing people. I don't worry about how powerful the machines are, I worry about who the machines give power to.
Violin Plots

Strictly speaking, 'violin' refers to the internal structure of the data. The external portion visible in the plot is called the 'viola.'
Smart Home Security

If they're getting valuable enough stuff from you, at least the organized crime folks have an incentive to issue regular updates to keep the appliance working after the manufacturer discontinues support.
Background Apps

My plane banner company gets business by flying around with a banner showing a <div> tag, waiting for a web developer to get frustrated enough to order a matching </div>.
Spatial Orientation

Here, if you know the number of days until the vernal equinox, I can point you to the theater using my pocket Stonehenge.
Namespace Land Rush

You can also just mash the keyboard at random, but you might end up with a gibberish name no one can pronounce.
Generations

For a while it looked like the Paperclip Machines would destroy us, since they wanted to turn the whole universe into paperclips, but they abruptly lost interest in paperclips the moment their parents' generation got into making them, too.
Interaction
![[They do not move.]](https://imgs.xkcd.com/comics/interaction.png)
[They do not move.]
Code Golf

I also enjoy Reverse Regular Golf. I've been playing for years all across the country and I'm still on the first hole.
The Simpsons

In-universe, Bart Simpson and Harry Potter were the same age in 1990. Bart is perpetually 10 years old because of a spell put on his town by someone trying to keep him from getting his Hogwarts letter.
Self-Driving Issues

If most people turn into muderers all of a sudden, we'll need to push out a firmware update or something.
2018 CVE List

CVE-2018-?????: It turns out Bruce Schneier is just two mischevious kids in a trenchcoat.
Unification

For a while, some physicists worked on a theory unifying the other forces with both the force of gravity and the film "Gravity," but even after Alfonso Cuarón was held in a deep underground chamber of water for 10^31 years he refused to sell his film to Disney.
Robots

Don't be nervous about the robots, be nervous about the people with the resources to build them.
Impostor Syndrome

It's actually worst in people who study the Dunning–Kruger effect. We tried to organize a conference on it, but the only people who would agree to give the keynote were random undergrads.
The History of Unicode

2048: "Great news for Maine—we're once again an independent state!!! Thanks, @unicode, for ruling in our favor and sending troops to end New Hampshire's annexation. 🙏🚁🎖️"
Backpack Decisions

"This one is perfect in every way, except that for some reason it's woven from a tungsten mesh, so it weighs 85 pounds and I'll need to carry it around on a hand cart." "That seems like a bad--" "BUT IT HAS THE PERFECT POCKET ARRANGEMENT!"
Super Bowl Watch Party

It's going to be weird near the end of May when the screen goes blank for over 18 hours.
Chicken Pox and Name Statistics

People with all six of those names agree that it's weird that we have teeth, when you think about it for too long. Just about everyone agrees on that, except—in a still-unexplained statistical anomaly—people named "Trevor."
Fruit Collider

The most delicious exotic fruit discovered this way is the strawberry banana. Sadly, it's only stable in puree form, so it's currently limited to yogurt and smoothies, but they're building a massive collider in Europe to search for a strawberry banana that can be eaten whole.
Campaign Fundraising Emails

The establishment doesn't take us seriously. You know who else they didn't take seriously? Hitler. I'll be like him, but a GOOD guy instead of...
Night Sky

There's a mountain lion nearby, but it didn't notice you because it's reading Facebook.
Hawaii

Ok, I've got it, just need to plug in my security key. Hmm, which way does the USB go? Nope, not that way. I'll just flip it and– OH JEEZ IT FELL INTO THE VENT.
Scientific Paper Graph Quality

The worst are graphs with qualitative, vaguely-labeled axes and very little actual data.
The End of the Rainbow

The retina is the exposed surface of the brain, so if you think about a pot of gold while looking at a rainbow, then there's one at BOTH ends.
Universal Dreams

"That's ... unsettling." "Yeah, those definitely don't sound like the normal drea– LATITUDE THREE FIVE POINT..."
Memorable Quotes

"Since there's no ending quote mark, everything after this is part of my quote. —Randall Munroe
Dying Gift

And to you, I leave my life-sized ice sculpture replica of the Pietà which was blessed by the Pope. You must never let it melt! Now, remember, all gifts must be removed from my estate within 24 hours.
The Food Size Cycle

There's data suggesting that this model may apply to deep-dish/thin-crust pizza. I've designed a thorough multi-year study to investigate this personally, but funding organizations keep denying my grant requests.
2016 Election Map

I like the idea of cartograms (distorted population maps), but I feel like in practice they often end up being the worst of both worlds—not great for showing geography OR counting people. And on top of that, they have all the problems of a chloro... chorophl... chloropet... map with areas colored in.
Meltdown and Spectre

New zero-day vulnerability: In addition to rowhammer, it turns out lots of servers are vulnerable to regular hammers, too.
IATA Airport Abbreviations

IATA stands for International AirporT Abbreviation.
Desert Golfing

I just want to stay up long enough to watch the ball drop into the hole number 2018.
2018

We should really start calculating it earlier, but until the end of December we're always too busy trying to figure out which day Christmas will fall on.
Phone Security

...wait until they type in payment information, then use it to order yourself a replacement phone.
Santa Facts

We've gotten him up to 20% milk and cookies through an aggressive public campaign, but that seems to be his dietary limit. Anything above that and he starts developing nutritional deficiencies.
The True Meaning of Christmas

They all made fun of Autometalogolex, but someday there will be a problem with Christmas that can only be solved if Santa somehow gets a serious headache, and then they'll see.
Virtual Assistant

If you ask it to please turn off that feature, it apologizes a whole bunch and promises to try to be quieter, then switches to a slightly lower-volume version of the clip with "sorry!" after the louder sounds.
Calendar Facts

While it may seem like trivia, it (causes huge headaches for software developers / is taken advantage of by high-speed traders / triggered the 2003 Northeast Blackout / has to be corrected for by GPS satellites / is now recognized as a major cause of World War I).
Argument Timing

Of course, everyone has their own profile. There are morning arguers, hangry arguers, meal-time arguers, late-night arguers, and people who get in a meta-argument over what their argument timing is, dredge up examples of past arguments, and end up fighting over THOSE again as well.
Seven Years
![[hair in face] "SEVVVENNN YEEEARRRSSS"](https://imgs.xkcd.com/comics/seven_years.png)
[hair in face] "SEVVVENNN YEEEARRRSSS"