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Posted by blenderob 1 day ago

A4 Paper Stories(susam.net)
372 points | 174 comments
Fiveplus 1 day ago|
Nice! The author touches on the area properties and here's the most practical life hack derived from the standard I personally use. It uses the relationship between size and mass.

Because A0 is defined as having an area of exactly 1 square meter, the paper density (GSM or grams per square meter) maps directly to the weight of the sheet.

>A0 = 1 meter square.

>Standard office paper = 80 gsm

>Therefore, one sheet of A0 = 80 grams.

>Since A4 is 1/16th of an A0, a single sheet of standard A4 paper weighs 5 grams.

I rarely need to use a scale for postage. If I have a standard envelope (~5g) and 3 sheets of paper (15g), I know I'm at 20g total. It turns physical shipping logistics into simple integer arithmetic. The elegance of the metric system is that it makes the properties of materials discoverable through their definitions.

rags2riches 1 day ago||
The 5 grams per sheet of common printer paper has certainly proven handy once or twice in some of my interactions in the informal economy.
tastyfreeze 1 day ago||
Same for the US 5 cent coin. Defined mass of 5 grams.
mannykannot 1 day ago|||
Don't tell the current administration that there's something so un-American about the currency: they will insist on fixing it, and probably retire Jefferson as well.
teachrdan 1 day ago|||
Fun fact: While the US spent more than 3 cents for every penny minted and distributed, it spends about 14 cents for every nickel minted and distributed!
jrussino 1 day ago|||
When they decided to stop minting pennies I think they should have gotten rid of nickels and (I know this will be controversial) quarters as well!

Keep dimes and ramp up production of half dollars. Then we can just drop the second decimal place and standardize pricing everything in 0.1 dollar increments.

The fact that quarters are still somewhat commonly used in machines (vending machines, parking meters, laundry) is probably the biggest practical obstacle.

xp84 20 hours ago|||
This may be the most practical go-forward plan. The Euro's .20 coins are also attractive too. But you're correct that quarters, as the smallest common currency that you can plausibly buy something with just a couple of them, are just everywhere, from laundry to car washes, so the pain in retiring them would be widely felt.

What I've learned from the penny retirement is that people are deeply distrustful of simple high school level statistics! Millions of people have angrily seethed that somehow stores are or will be using the penny retirement to rob them, despite knowing that most transactions have an unknowable amount of different items, and sales tax, so attempting to manipulate prices to gain a statistical advantage out of rounding would be incredibly difficult and would yield a pitiful return. Let alone how the cash transaction share is declining every year.

aidenn0 15 hours ago|||
I would have gotten rid of nickels and dimes; then everything is priced in 1/4 dollars.
braiamp 1 day ago|||
Which is pennies compared to the amount of economic activity that those pennies facilitated.
xp84 20 hours ago||
> activity that those pennies facilitated

Do you mean in the zinc mining and Coinstar? Pennies have been a bizarre ritual for years, wherein the government made zinc worth less than its pre-minted value, distributed them to banks nationwide, banks in turn to stores, stores using them once to give meaningless amounts of money to customers, customers in turn immediately throwing them on the ground or at best eventually dumping them into a coinstar, and coinstar returned those to banks.

Nothing of value was going on there. I'd rather pay any zinc miners and coinstar drivers who have been displaced to play video games all day while still saving all those resources, fuel, and most of all, time.

SoftTalker 1 day ago||||
I mean really, everything smaller than a quarter should go.
lostlogin 23 hours ago||
Erasing small coins will be an interesting race between inflation and electronic payments.

I’m in New Zealand and haven’t had a wallet in a decade, never using cash.

Theoretically one should carry a drivers licence when driving but it’s never come up and I have a photo of it thats worked with police before.

bigiain 20 hours ago|||
I, for one, look forward to the new 5oz "Donald Trump Freedom Nickel". Probably resulting from a deal he did with the Big Trousers lobby groups to wear out coin pockets faster.

(I would have made a gag about a 7g replacement nickel, but you people have already used up the team "quarter" for different denomination. Although the idea of a new 40 cent coin called an "eight ball" amuses me...)

ahazred8ta 19 hours ago|||
And $20 in dimes or quarters is 1 lb. US silver coins are 0.2268 grams per cent.
pvillano 19 hours ago|||
Paper's uniform mass per area makes it useful calibrating very tiny scales. 1mm² of 80 gsm paper will weigh about 80 micrograms.

"Measure the mass of an eyelash with a DIY microbalance" by Applied Science https://youtu.be/ta7nlkI5K5g

ctxc 1 day ago|||
TIL GSM is just g/sq m. Like duh, feel so stupid xD
holowoodman 1 day ago||
It's not you who should feel stupid.

The person deciding to use nonstandard "GSM" as a unit instead of the proper "g/m²" needs to feel stupid...

gjm11 1 day ago|||
I'm not sure I agree. "GSM" is three syllables, versus four for "grammes per square metre". You can write it correctly using only characters everyone knows how to type quickly on their keyboard, versus either finding a way to get that superscript ² or else typing something like g/m^2 which is uglier and longer. And you can use it comfortably even if you are a complete mathematical ignoramus (you just need to know things like "larger numbers mean heavier paper" and "cheap printer paper is about 80gsm" and so forth) without the risk of turning g/m² into the nonsensical g/m2 or something.

(But arguably what whoever decided on "gsm" should have done was to just use "g", with the "per square metre" left implicit.)

Doxin 12 hours ago|||
Roughly no one already says GSM. When talking about paper you'll hear people say things like "That's a sheet of 120 gram"

GSM basically only ever appears in print. If someone DOES ask "what does 120 gram mean here?" the clarification is going to be "Oh that's grams per square meter" and not "Oh that's gee es em"

I should mention GSM is also probably an americanism. I'm in the EU and out of the five packs of different kinds of art paper four are labeled in g/m2, and one has no labeled weight at all. None of them are marked in GSM as that abbreviation only works in english, while g/m2 works in all languages.

roryirvine 9 hours ago||
In the UK, "gee es em" was the usual term I heard at the local paper merchants when I was a regular customer in the late 90s - early 2000s.

Of the four reams of paper/card I have at home, two are labelled in "gsm", one is "g.m⁻²", and one uses both "g/m²" and "gsm" in different places. Weirdly, it seems that the specialist stuff is more likely to use "gsm" than the everyday 80 g/m² A4.

cassepipe 1 day ago|||
I beg to differ. You can totally get away with g/m2 which is not hard to type and crucially has a / to hint you what it could be about

"gsm", or even more so "GSM", belongs to the reign of abbrevations and put my brain on the wrong track

morganf 1 day ago||||
"The person deciding to use nonstandard "GSM" as a unit instead of the proper "g/m²" needs to feel stupid..." ---> This is the sort of HN comment that I can't figure out if it's serious or a joke. I can read it in different voices and come to opposite conclusions haha
bmicraft 1 day ago||
While we're at it, mph and the abomination that is "kph" (= km/h) even more so need to die in a fire.
bregma 1 day ago||||
You mean gm⁻² ?
holowoodman 10 hours ago||
Well, yes. I was just too lazy to find the superscript minus ;)
formerly_proven 23 hours ago||||
Some cursory search suggests "gsm" for grammature is confined to the US, everyone else uses g/m² or just g.
ascorbic 22 hours ago||
It's gsm in the UK too
toss1 21 hours ago||||
Ummm, not really, No.

The shorthand "gsm" is a completely standard alternative in some industries.

I work in advanced composites. Different weights and weaves of technical fabrics such as carbon fiber, kevlar, fiberglass, etc. are always specified in "gsm". For example, some common fabrics would be a "Carbon Fiber 3K 200gsm Twill" or a "High Modulus 12K 380gsm Carbon Fiber Plain Weave". (the "3K" and "12K" refer to the number of carbon fiber strands in each yarn in the weave, and the "Twill" and "Plain Weave" refer to the pattern in which the yarns are woven into a fabric.)

I'm sure "gsm" came to be commonly used instead of the more scientific "g/m²" or "g/m^2" because no one is doing that kind of math about the materials, and it is a lot easier to type "gsm" vs either of the other two which require at least a Shift for the caret or getting out the superscript font attribute.

bigiain 19 hours ago||
Interestingly, sail cloth (for sail boat sails) is measured in ounces per square yard, and is just referred to by the weight with the square yard assumed - like "8oz Nylon mainsail" or "4oz ripstop spinnaker". (Or at least it used to be, my expertise here is more than 30 years out of date now.)
KPGv2 1 day ago|||
> The person deciding to use nonstandard "GSM" as a unit instead of the proper "g/m²" needs to feel stupid...

mph, kph, cps, etc

yencabulator 1 day ago|||
I most definitely grew up with km/h, not kph. "k" is not an acceptable way to abbreviate kilometer in a world where kilograms are used.
fragmede 1 day ago||
Curious what you're doing that "kilograms per hour" might get used by normal people in everyday conversation. Fast food restaurant or a weight loss clinic?
yencabulator 1 day ago||
The whole point of SI units is to not live in a world of uncertainty, ad hoc terminology, and name collisions.
marcosdumay 1 day ago||||
Yeah, the people insisting on writing those are on the wrong.
dorfsmay 1 day ago||
Agreed but we do have to interact with them. I once tried to sell a car with 140 Mm and got nowhere. I then changed the add to 140_000 km and got a lot more interest.
TRiG_Ireland 1 day ago||
My interdental brushes claim that the wire is 0.8 megamolar wide, which is not a normal measure of width.
cassepipe 1 day ago|||
I wonder if the international society of dentists keeps a standard molar in a safe somewhere
kergonath 22 hours ago||||
It is probably an indication that they should fix their caps lock keys, however. Like the guys who sells bottles with volumes in ML.
bregma 1 day ago||||
That would be 4.82x10²⁹ somethings wide.
astrolx 1 day ago||||
0.8 Mmol?
marcosdumay 1 day ago|||
0.8 MM

The symbol for molar is just the "M". "mol" denotes the Avogadro constant.

JadeNB 1 day ago|||
> My interdental brushes claim that the wire is 0.8 megamolar wide, which is not a normal measure of width.

0.8 megamolar = 800,000 teeth? That, uh, seems pretty wide for an interdental brush.

snow_flake 1 day ago|||
Oh nice, that is a neat trick! One small nitpick (that makes no difference): The side lengths of the ISO Ax formats are rounded to the next mm, so actually the A0-format has an area of 0.999949m^2
orthoxerox 1 day ago||
Not to the next, to the nearest, otherwise it would have to be slightly larger than 1m^2.
wolfi1 1 day ago|||
that reminds me of an old joke: how doe the postal services make their profit? I don't get it. - Ah, that's easy. How much wieght may letters have? - 20g - And how much weight do the average letters have? - About 6g. - See? That's their profit
bmicraft 1 day ago||
I really don't get it.
nhumrich 20 hours ago||
It's technically a 300% margin because they are charging you for 20g but only shipping 6g.
thaumasiotes 1 day ago||
> I rarely need to use a scale for postage. If I have a standard envelope (~5g) and 3 sheets of paper (15g), I know I'm at 20g total. It turns physical shipping logistics into simple integer arithmetic.

...was using a scale for postage a concern? If you're shipping things on the order of three sheets of paper, you're way below any conceivable threshold. USPS charges a flat rate on letters under 370 grams!

If you're sending 1,700 pieces of looseleaf paper in a box... just weigh the box.

FinnKuhn 1 day ago|||
German postage for letters is under 20g, under 50g and under 500g so I had this issue a few times so far when sending a few letters a day over a few weeks. You can see it here for international letters for example: https://www.deutschepost.de/en/b/briefe-ins-ausland.html

Thankfully I just had a scale, but I can see this being helpful when you don't.

tibordp 1 day ago||||
Given that we are talking about A4 papers and grams, I'd bet this wasn't in the US.

In Europe, the typical flat rate is up to 100g for standard letters. And that's 20 sheets, which is not a particularly unusual letter to send.

prmoustache 10 hours ago||
But 20 sheets do not fit in a regular DL or C5 envelope so you already have an hint that you may check the limits, you usually send them in a reinforced C4 enveloppe.
pif 1 day ago||||
French "La Poste" sets the first threashold at 20 g.
tonyedgecombe 1 day ago||
You will be using Aerograms soon.

https://en.wikipedia.org/wiki/Aerogram

On a related subject I just discovered that sending a letter in Denmark now costs a minimum of $4.50.

tonyedgecombe 1 day ago||||
>USPS charges a flat rate on letters under 370 grams!

In the UK the limit for a letter is 100 grams:

https://www.royalmail.com/sending/uk/1st-class

2b3a51 1 day ago||
And as that link eventually shows there are limits on the dimensions as well. I sometimes think a simple table might be better than these interactive pages, but I suppose it has to work on a phone.

24 by 16.5 by 0.5 cm for the standard 1st class letter. So you could send an A5 booklet made of less than 20 sheets of A4 (80 g/m^2) paper as a standard letter.

If the postage is short, our lovely privatised Post Office holds the letter and makes the recipient pay the excess.

Back on thread: Repeatedly fold an A0 sheet of paper in half. How many folds can you do? A ream (500 sheets) of 80 g/m^2 paper is about 2.5cm thick. (good when teaching geometric progressions).

unwind 1 day ago||||
In Sweden, the lowest postage (one stamp, 22 SEK or around $2) is for max 50 grams.
ericpauley 1 day ago|||
A first class forever stamp only covers 1oz (28g).
jihadjihad 1 day ago||
CGP Grey has a video [0] that goes into some, let's just say deeper, detail into metric paper that is well worth a watch if you haven't seen it.

0: https://www.youtube.com/watch?v=pUF5esTscZI

edit: fat-fingered CPG, thanks @ProllyInfamous

ProllyInfamous 1 day ago|
You beat me in posting this (I searched for "CGP," first — you mispelled so I didn't see your comment).

----

My favorite CGP Grey video is Metric Paper..., which explores the vast (but limited) world we live in, from plancs to observable universe.

[•] <https://www.youtube.com/watch?v=pUF5esTscZI>

Before generative AI videos, this had been what I considered "the most psychedelic experience one can have without doing drugs." It's still a trip...

abraxas 1 day ago||
As a European living in North America I developed a weird cognitive dissonance. When I'm in North America the regular printer page (US Letter) seems too squat. When I'm in Europe the A4 page looks too svelte. I now need an in-between format for it to look "right".
johanyc 8 hours ago||
> When I'm in Europe the A4 page looks too svelte.

Off-topic but as a non-native English speaker, TIL what svelte means lol. I often get exposure of new words first from a product name. Same happened with Chrome.

trueismywork 1 day ago|||
B5
dghf 8 hours ago|||
Assuming "squat" and "svelte" refer to the aspect ratio, isn't B5 going to look just as "svelte" as A4?
_carbyau_ 16 hours ago|||
B series paper sizes is a thing I knew but wish I didn't.

See also C series. Thankfully largely a moot point now.

dominicrose 1 day ago||
Also sqrt(2) isn't the golden number. Not far from it but still...
wyan 23 hours ago||
The golden ratio makes for even less balanced paper than sqrt(2)
bitdivision 1 day ago||
I happened to be looking at ski boot fitting this morning and came across a web app from fischersports that allows you to measure your feet using your phones camera. Surprise surprise it uses a sheet of A4 paper.

App is about halfway down this page, https://www.fischersports.com/rc4-podium-rd-worldcup-strd/U0... under 'find your size' and is powered by https://volumental.com/

n4r9 1 day ago||
Fun article. I liked the bit about how the size of A0 can be uniquely determined from abstract constraints. But I'm not convinced that the "Measuring Stuff" section involves anything more than memorising the exact dimensions of A4. I don't see how it applies the stuff about preserved ratios.

Nitpick: typo in the dimensions for A3.

MrSkelter 8 hours ago||
The article declines to mention how precise paper is. The corners are very, very square and the lengths are very, very precise.

Better than an average square, better than an average ruler.

pvillano 19 hours ago||
On one hand, you could do the measuring section with any standardized rectangle. On the other hand, any excuse to talk about metric paper

Letter paper, credit card, banknote, business card, etc.

niemandhier 1 day ago||
25. Of October 1786: Lichtenberg suggested his friend Beckmann a paper format in the aspect ration 1/√2.

»einen Bogen Papier zu finden, bey dem alle Formate … einander ähnlich wären. … Die kleine Seite des Rechtecks muß sich nämlich zu der großen verhalten wie 1:√2 oder wie die Seite des Quadrats zu seiner Diagonale. Die Form hat etwas angenehmes und vorzügliches vor der gewöhnlichen.«

DeRock 1 day ago||
Here’s a better tip to measure things without a proper measuring device: spread out your hand on a table and measure the distance between your pinky and thumb. Remember that. Now when you need to measure something just measure it in number of pinky-thumb-stretches. I can quickly get the dimensions to +/- an inch by doing a few quick walks with my hand.
qznc 1 day ago|
It is hand to remember a few finger/knuckles/elbow/shoulder combinations for common measures. One of your phalanges should be ~1 inch, for example, and one of your finger nails is probably ~1 cm wide.
bombcar 1 day ago|||
There's a reason that the English system of measurement had things like "hand" and "foot" - because when you're not measuring things exactly, close enough and commonly available is fine.
masswerk 8 hours ago||
Only, I think, a foot is actually a half a cubit (length from elbow to fingertip). So, sort of a misnomer, rounded to the nearest body part.
adzm 1 day ago|||
Or be like the mythbusters guy and get a ruler tattooed on your arm!
Lio 1 day ago||
Metric is beautiful.

I remember when I first got into metal work and wanted to get some tapping drills.

There are a plethora of standards when you start looking into it. For what I make though if I use metric I really only need one, ISO Coarse.

Metric is just well thought out and easier.

Animats 1 day ago|
For small screws, in the millimeter range, the jump between metric sizes is too big. So, in addition to M1, M2, M3, M4, M5, etc. standard metric screws include M1.4, M1.6. M1.8, M2.5, and M3.5 (rare) to fill in the gaps.

Screw sizes and drill sizes should have been sized by a ratio, like resistor values. But that would have been a pain for manual machining.

Lio 8 hours ago||
Yep, as it is some sizes are easier to work with.

Domestic drill sets don't seem to be designed for tapping holes but if you stick to M3, M6 and M10 the tapping sizes do correspond with the 2.5, 5 and 8.5mm drills[1].

I guess if it was based on a ratio system you would need special tapping drills for all of them.

e.g. M4 needs a special 3.3mm tapping drill already.

1. According to my trusty Zeus tables.

tasuki 22 hours ago||
I use my fingers:

When I spread my index finger and middle finger, not entirely as far as they can go, but rather far, that's 10 centimetres.

Thumb to pinky is 22 centimetres. These two are often precise enough for me.

PlunderBunny 22 hours ago|
My partner (an architect) does something similar, plus - when she holds her arm out straight - the distance from the tips of her fingers to the opposite shoulder blade is almost exactly a meter.
wt__ 8 hours ago|
Some Moleskine cahier notebooks are wrapped in a paper sleeve that has a ruler printed on the back. Inches on one edge; centimetres on the other (a slight improvement for non-American users over Field Notes notebooks, with a ruler on the inside back cover that’s inches only - also the sleeve is rather longer, 28cm in fact).
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