# Difference between revisions of "526: Converting to Metric"

 Converting to Metric Title text: According to River, "adequate" vacuuming systems drain the human body at about half a liter per second.

## Explanation

Most people will eventually develop an intuitive feel for how big certain measurements are (e.g., how long an inch or a foot is, how much a pound weighs). This comic points out that people who were brought up using the imperial system probably don't have the same intuitive understanding for metric units and attempts to provide some benchmarks for these people. Most of the benchmarks are common sense, highly-useful ones (e.g., if it's 30 degrees centigrade [86 °F], you'd be quite comfortable outside dressed for the beach) but some of the benchmarks are humorous and/or completely useless. Benchmarks include:

### Temperature

• Earth's Hottest: 60⁠°C [140 °F]: The hottest temperature recorded on earth is actually "only" 56.7. There have been reports of ten-twenty degrees higher (70-80⁠°C) but these measurements are not verified or accepted as world records.
• Various heat waves: Dubai is a city in the United Arab Emirates, and is smack-dab in the middle of an equatorial desert, so their heat waves can get hot!. The southern Unites States will typically be a few degrees hotter than the northern United States simply because it's closer to the equator, but as mentioned they're both above "Beach Weather".
• 30°C [86 °F]: A little too hot so perfect for a trip to the beach.
• 20°C [68 °F]: Is defined as room temperature in many experimental settings. For some this would feel a little cool. But 25°C [77°] would as mentioned be too warm for room temperature...
• 10°C [50 °F]: Definitely wear a jacket. Especially if there is just a little breeze.
• 0⁠°C [32 °F]: The freezing point of water (32°⁠F)
• -5 to -10°C: In Moscow -10°C is not really that cold - it can go "spit goes clink" cold in Moscow, whereas -5°C [23 °F] in Boston may be very cold...
• -20°C: FuckFuckFuckCold and -30°C - Fuuuuuuuuuuuuck!: This is implied to be basically what some people would say when they step outside at this temperature. In reality, it would be best to keep ones's mouth firmly closed. At -30°C, without taking wind chill into account, exposed skin will feel painful in under a minute and frostbite could begin in as little as ten minutes [1].
• -40⁠°C: Spit goes "clink": As shown in the drawing your spit would freeze before it hits the ground. This is the crossing point of the two temperature scales i.e. -40°C = -40 °F.

### Length

• 1 cm [.4 inch] : Width of microSD card and 3 cm - Length of SD card: Refers to the memory cards used in cell phones, digital cameras, etc.
• 12 cm [almost 5 inches]: CD rom are a common object so nice to know it is a dozen centimeters.
• 14 cm [5 1/2 inches]: Most males would probably exaggerate the size of their penis, but 14–15 cm is very average.
• 15 cm [almost 6 inches]: A Bic Pen
• 80 cm [31 1/2 inches]: A typical doorway is also of standard size. This is barely over the minimum size typically required by codes for buildings [30 inches or 76.2 cm], but more than 50% over the size required for aircraft emergency exits. (It may seem illogical that larger doors are required in buildings than in airplanes, given airplanes are arguably more dangerous. However, there is no real disadvantage to using larger doors in buildings, which are not significantly pressurized, but using larger doors in aircraft would increase the force on the door caused by cabin pressure proportionally.)
• 1 m [39.37 inches]: Lightsaber Blade: Refers the weapon used in the Star Wars movie franchise. Canonically, the length of a Lightsaber's blade varies greatly depending on the setting of the weapon, but "one meter" is by no means a bad approximation.
• 170 cm [5 feet, 7 inches]: Summer Glau: Refers to the height of the actress who portrays the character River Tam on the TV show Firefly.
• 200 cm [6 feet, 6 and 3/4 inches]: Darth Vader: Refers to the height of the main antagonist from Star Wars.
• 2.5 m [almost 10 feet]: Ceiling - of course very much depending on which type of building you are in!
• 5 m [almost twenty feet]: Car Length - also very much depending on the car...
• 16 m 4 cm: Human tower of Serenity crew: Again, this refers to the Firefly TV show, which takes place mostly on a space ship called Serenity.
• Presumably, if all the crew of Serenity were stacked on top of each other, this would be their combined height.
• The comic depicts four characters from the show standing on top of each other; the bottom figure is the crew's captain, Malcolm Reynolds in his signature coat. Judging from the other drawing of Summer Glau from the volume section, she is standing on top of the captain.
• The other five members of the crew should also be stacked on top of these four to reach the 16m height - giving them an average height of 1.82 m (12 cm more than Summer Glaus height!)

### Speed

Here both the SI unit m/s as well as the more used unit kph (km per hour) is given.
• 5 kph [3 mph] - 1.5 m/s: Walking at a normal pace
• 13-25 kph [8-15 mph]: Jogging to sprinting.
• 35 kph [21.75 mph] - 10 m/s: Fastest human: As of 2009, the fastest a human has been recorded to run in a single sprint is actually 45 kph, a record set by Usain Bolt.
• 45-55 kph: Both cats and rabbits go much faster than normal people.
• 75 kph [46.6 mph] - 20 m/s: Raptor: It's a comic written by Randall, of course a reference to the velociraptors from Jurassic Park was going to be here.
• 100 kph - 25 m/s: A slow highway (62 mph).
• 110 kph [68.35 mph] - 30 m/s: Interstate (65 mph): Refers to the American highway system. (65 mph would actually be only 104.6 kph.)
• 120 kph - 35 m/s: Speed you actually go when it says "65": People routinely break the aforementioned speed limit, and the police typically don't mind as long as it's not posing any danger. For the record, 120 kph is 74 mph.
• 140 kph - 40 m/s: Raptor on Hoverboard: The hoverboard is probably a reference to the Back to the Future Part II, though it's a fairly common trope in older science fiction stories. Randall obviously did a lot of google searching on this subject the week before - see 522: Google Trends.

### Volume

• 3 ml: The amount of blood in a fieldmouse.
• 5 ml: A teaspoon - a very common measure.
• 30 mL: Nasal Passages and 40mL - Shot Glass: The comic points out that you could just about fill a shot glass using the mucus from your nose. Since shot glasses are usually used for mixed drinks, the comic jokes that this mucus could constitute a new, disgusting drink - and this is depictured in the drawing.
• 350 ml: Soda can (this is roughly correct for the cans used in the U.S., which hold 12 fluid ounces; in Europe, soda cans commonly hold 330ml or 500 ml).
• 500 ml: Water bottle (this is the also the volume of a European water bottle).
• 3 L: Two-liter bottle: Refers to a bottle which contains two liters (in the US usually soda). There is debate as to the reason for the discrepancy in volume.
• 5 L: An adult male has about 5 L of blood in his body (An adequate vacuuming system could drain this blood out in 10 s - as per the title text!)
• 30 L: Milk Crate: Refers to a type of small box originally used to transport milk but now often in demand to be used as bicycle basket, storage spaces, etc.
• 55 L: Summer Glau: Again, this refers to the actress from Firefly.
• 65 L: Dennis Kucinich: An American politician belonging to the Democratic party, noted for his relatively strong (for the US) leftist views.
• 75 L: Ron Paul: An American politician belonging to the rival Republican party, noted for his strong rightist views.
• 200 L: Volume of refrigerator.
• As shown in the drawing of this part of the comic, the three persons mentioned above - Glau, Kucinich and Paul (summing up to 195 L) - could in principle all fit inside a standard refrigerator. Cueball thus attempts to push them all inside of one - though it would obviously be very uncomfortable for all parties involved to be trapped in such a small space with not much room between them.

### Mass

• 3 g: Peanut M&M: A small chocolate candy with a peanut inside
• 100 g: Cell phone - this very much depends on the age of the cell phone, and the type etc.
• 500 g [1 lb.]: A bottle of water contains 500 ml according to the volume section and thus have mass of 500 g.
• 1–3 kg: Different types of laptops. The newest and the best is the lightest...
• 5 kg [11 lb.]: LCD Monitor: A modern flat-screen-style monitor.
• 15 kg: CRT Monitor: An older-style, cathode ray tube-based monitor.
• This ends the section on computer screens, which overrode the normal sequence by weight as the next two feline inspired entries are lighter than the two before.
• 4 kg: Cat and 4.1 kg - Cat (With Caption): Refers to the internet's love of putting captions on cats. Usually, this is done in a graphics program, but here the cat is actually physically carrying around his caption. The "with caption" part is most likely a reference to 262: IN UR REALITY, where Black Hat glues captions to cats, after running out of staples.
• 60 kg [130 lb.]: Lady - for instance if she is Summer Glau - could be her again depicted in the comic - average weight of an adult woman.
• 70 kg [150 lb.]: Dude - here depicted as Cueball who is the average guy, and 70 kg is average weight for an adult man.
• 150 kg: Shaq: Shaquille O'Neal, a famously tall basketball player.
• 200 kg [440 lb.]: Your Mom
• 220 kg: Your Mom (incl. 20 kg of cheap jewelry) and
• 223 kg: Your Mom (also incl. 3 kg of Makeup)
• These last refers to a common type of Your mom joking insult whereby someone insults someone else's mother in a creative way. Here, the comic slyly calls your mom fat, then implies she wears way too much jewelry and finally also almost 7 pounds of makeup. This is a common theme in xkcd. (Twenty kg of "cheap" jewelry has several times the volume than 20 kg of gold jewelry, because of the difference in density.)

## Title text

The title text refers once again to Summer Glau's Firefly character, River, who (after being subjected to a long series of medical experiments) is severely mentally ill and often comes out with macabre — though scientifically accurate — pronouncements.

## Transcript

Guide to Converting to Metric
The key to converting to metric is establishing new reference points. When you hear "26 degrees centigrade", instead of thinking "That's 79 degrees fahrenheit" you should think, "that's warmer then a house but cool for swimming." Here are some helpful tables of reference points:
Temperature:
60 degrees centigrade - Earth's Hottest
45 degrees centigrade - Dubai Heat Wave
40 degrees centigrade - Southern US Heat Wave
35 degrees centigrade - Northern US Heat Wave
30 degrees centigrade - Beach weather
25 degrees centigrade - Warm Room
20 degrees centigrade - Room Temperature
10 degrees centigrade - Jacket Weather
0 degrees centigrade - Snow!
-5 degrees centigrade - Cold Day (Boston)
-10 degrees centigrade - Cold Day (Moscow)
-20 degrees centigrade - FuckFuckFuckCold
-30 degrees centigrade - Fuuuuuuuuuuck!
-40 degrees centigrade - Spit goes "clink"
[Stick figure next to last three lines.]
Man: Pthoo [Man spits.]
Spit: Clink! [Spit bounces off ground.]
Length
1cm - Width of microSD card
3cm - Length of SD card
12cm - CD Diameter
14cm - Penis
15cm - BIC pen
80cm - Doorway width
1m - Lightsaber Blade
170cm - Summer Glau
200cm - Darth Vader
2.5m - Ceiling
5m - Car-length
16m4cm - Human tower of Serenity crew
[Human tower of Serenity crew stick figures depicted taking up from second line of panel to bottom.]
Speed
5 kph - 1.5 m/s - Walking
13 kph - 3.5 m/s - Jogging
25 kph - 7 m/s - Sprinting
35 kph - 10 m/s - Fastest Human
45 kph - 13 m/s - Housecat
55 kph - 15 m/s - Rabbit
75 kph - 20 m/s - Raptor
100 kph - 25 m/s - Slow Highway
110 kph - 30 m/s - Interstate (65 MPH)
120 kph - 35 m/s - Speed you actually go when it says "65"
140 kph - 40 m/s - Raptor on Hoverboard
Volume
3mL - Blood in a fieldmouse
5mL - Teaspoon
30mL - Nasal Passages
40mL - Shot Glass
So when it's blocked, the mucus in your nose could about fill a shot glass.
[Image of a shot glass.] Related: I've invented the worst mixed drink ever.
350mL - Soda Can
500mL - Water Bottle
3L - Two-Liter Bottle
5L - Blood in a Human Male
30L - Milk Crate
55L - Summer Glau
65L - Dennis Kucinich
75L - Ron Paul
200L - Fridge
[Cueball shoving Ron Paul, Summer Glau, and Dennis Kucinich into fridge.]
[Above fridge, circled, is 55+65+75<200]
Mass
3g - Peanut M&M
100g - Cell Phone
500g - Bottled Water
1kg - Ultraportable Laptop
2kg - Light-Medium Laptop
3kg - Heavy Laptop
5kg - LCD Monitor
15kg - CRT Monitor
4kg - Cat [Drawing of cat.]
4.1kg - Cat (With Caption) [Drawing of cat, going "Mrowl?", and holding a caption.]
70kg - Dude
150kg - Shaq
[Stick figure of Megan and Cueball beside previous 3 lines.]
200kg - Your Mom
220kg - Your Mom (incl. cheap jewelry)
223kg - Your Mom (also incl. Makeup)

# Discussion

Why is 3L a two-liter bottle?75.69.96.225 21:16, 28 April 2013 (UTC)

Because this is America and we supersize our sodas! 72.68.9.56 (talk) (please sign your comments with ~~~~)
It is the volume of the bottle itself. I have added this explanation. Sten (talk) 22:39, 29 August 2013 (UTC)
A 2L bottle doesn't take 3L of space, not even close. I also think it's a reference to overly large drinks in the US. But even if it isn't, the current explanation is wrong. 108.162.229.34 22:28, 12 December 2013 (UTC)
I suspect he's just messing with us, because the approximate volume of a two-liter bottle should be obvious. Many beverages sold in the US are already labeled in metric. Soda is routinely sold in one and two liter bottles, with three-liter bottles common in some markets. Bottled water is often sold in liters and half-liters. Liquor and wine are sold in 375 and 750 mL bottles. Also, since 1 quart = 946 mL, an approximate (+/- 5%) mental conversion from quarts to liters is already quite easy. Fryhole (talk) 01:35, 25 January 2014 (UTC)
Yes. He is just joking. The name of the bottle contains its volume. The 3 liter measurement is a joke. It would be like saying a cup has 2 cups of volume. flewk (talk) 01:58, 4 January 2016 (UTC)
My coffee cup is 12 ounces. Given a standard 8 ounce cup, my coffee cup is 1.5 cups.Seebert (talk) 15:24, 16 February 2016 (UTC)

My names River, that is all --139.216.242.254 02:52, 29 August 2013 (UTC)

Tick tock, goes the clock, 'till River kills the Doctor

Earth's hottest is 70,7 °C... 199.27.128.29 03:06, 24 February 2014 (UTC)

The world record as per wikipedia (and Guiness) is "only" 56.7. See corrected explanation above. Kynde (talk) 17:03, 6 March 2014 (UTC)

There was an incomplete asking for checking all measures and also for making sure that the references to serenity and velociraptors was mentioned. I did this, the last two by assigning the categories (firefly), and then also creating a new category:Your Mom. I now consider this explanation complete. Although if someone will speculate two whom the remaining two from the Serenity crew tower then please do so ;-) Kynde (talk) 17:03, 6 March 2014 (UTC)

Simon and Kaylee is my guess. 173.245.55.85 22:17, 30 June 2014 (UTC)

The speed of rapors given here is very different from 135: Substitute. B jonas (talk) 14:58, 25 March 2014 (UTC)

This sentence in the 'Mass' section has a [small] error: 'This is a common theme in XKCD.'-- it should be 'xkcd', not 'XKCD'. See the website for Randall's personal opinion on this. Anyways, it's small, but kinda stands out if your a reeallyy hardcore fan. 173.245.55.73 05:39, 9 April 2014 (UTC)

Thanks for your hint, an update is done. But please add your comments here at the bottom. --Dgbrt (talk) 21:26, 9 April 2014 (UTC)

-40 degrees centigrade is also -40 degrees Fahrenheit! The only such temperature.--DrMath 07:51, 7 July 2014 (UTC)

This is tagged with "Featuring real people" -- I don't see any real people in here, should we removethat tag? Spongebog (talk) 02:21, 25 July 2014 (UTC)

It refers to Shaq, Ron Paul, Dennis Kucinich, Summer Glau, your mom... --Pudder (talk) 08:18, 29 September 2014 (UTC)

Ron Paul is not a republican though. Yourlifeisalie (talk) 16:33, 5 May 2015 (UTC)

kph got me confused, because "km/h" is the usual way of displaying kilometers per hour. 162.158.90.212

As a Maine resident I concur with this sentiment: "at -30°, the user is incapable of closing their mouth after starting the first "fuck", and so extends it into one long one." However, try uttering the word "fuck" without closing your mouth... uck-uck-uck... Npsych (talk) (please sign your comments with ~~~~)

13kph is not a typical jogging pace. At least I hope not. That would make me depressingly slow. 162.158.150.100 (talk) (please sign your comments with ~~~~)

The whole point of this comic

I thought the whole point of this comic was NOT to think in terms of non-SI units. The only reason (we) Amercans cling to customary/imperial units is because when some quantity of something is expressed in SI units you may as well tell them it's however many quatloos, because the average American has no idea what the units are like...nothing to which to compare that item. Approach learning SI units EXACTLY how you learned customary units: pick up a kilo (pound) and feel how much Earth's gravity tugs on it, stick your hand out in the outdoor air and feel what the NWS or a thermometer tells you what the C (F) temp is, eyeball a meter (yard) stick and try to remember how long that is, and so on. You're only hamstringing yourself by constant numeric conversions to some other system. For example, just accept a cm is a cm, and DON'T WORRY about how big that is in any other system. IMHO it is counterproductive to have the customary units (the conversions) in this explanation, and ALL of them should be removed. -- RChandra (talk) (please sign your comments with ~~~~)

Objection: In Australia are bottled drinks are 600 mL. --162.158.2.222 00:45, 6 March 2016 (UTC)

Was it really necessary to say 'Season 1' when talking about Firefly?  ;_; 108.162.219.68 04:10, 4 May 2016 (UTC)

Anyone know if there's something like this comic for learning Customary when you're used to Metric? I have a European friend with an American copy of D&D 5th edition that's tasked with DM'ing on short notice. 162.158.122.144 21:43, 26 January 2017 (UTC)

25 m/s is 90 km/h, not 100 km/h as stated in the comic. Is this also supposed to be a joke? 162.158.222.46 (talk) (please sign your comments with ~~~~)

The inaccuracy is mentioned in the explanation. And please sign you comments.--Dgbrt (talk) 20:48, 25 September 2018 (UTC)

23 degrees is a more comfortable value for room temperature. It also gets used in school physics questions, where we were allowed to convert it to 300 kelvin. (Sorry, but 26.85 degrees is too warm for a room.)162.158.39.41 16:58, 14 October 2018 (UTC)