Monday, September 28, 2009



What is a Number 2 pencil?
Does 0.5 equal HB?
Does #2 = HB?
Is HB mechanical pencil the same as No 2 pencil?
No 2 Mechanical Pencil = 0.5 HB


I think this is all covered in various other posts on this blog, but I’m going to try and be a helpful guy and put it all in one place, all nice and succinct. I personally believe all this to be true, from having used a pencil or two over the years and from the accumulated wisdom of commenter’s on this and other blogs, but nothings certain apart from death and taxes. So, the questions.

What is a Number 2 pencil?
It’s a pencil with 2, #2, No. 2 or something like that written on it.

Surely there’s more to it than that?
No, not really.
There are no rules, standards, test methods, etc to define it. #2 just means it’s their standard writing grade normal hardness / darkness pencil. The manufacturer just makes what they think is their ordinary everyday writing grade pencil and calls it No 2. One manufacturer’s idea of #2 can be quite different from another’s, there is a big range of lead hardness, darkness, etc that are all called Number 2.

Does a No 2 pencil = a HB pencil?
No 2 and HB are both lead hardness grade scale measurements. There’s no standardised definition of No 2 or of HB but they are both the same thing – the ordinary everyday writing grade.

Why are wooden pencils called #2 and mechanical pencils are called HB?
History. Industry non-standardisation. Two names for the same thing.
Just like the metric and imperial measurement systems - some industries and some parts of the world say No 2 pencil and others say HB pencil.

Why do they say I have to use a No 2 pencil for those scantron bubble tests?
History. Basically they haven’t got any idea either, but if the say “Must use a No. 2 pencil” just like they have for decades they feel safe, because that’s what everyone says, and always has said, and it’s always been OK in the past. If they say anything else and the machine doesn’t read it properly you’ll probably ring a lawyer, so they just repeat the same old mantra and feel safe.

So you are kind of saying it’s all kind of rubbish?

So I can use an HB mechanical pencil?

So I can use anything at all?
Well that’s going too far. You have to make a mark for the machine to read, but any reasonably dark pencil will do. It probably also has to have a fairly distinct edge, a sharp change from white paper to dark pencil mark. The machine isn’t that smart – it doesn’t know you used a mechanical pencil, it just sees a reasonably dark pencil blob and is happy. The point is, there is absolutely no set of rules to define what a Number 2 pencil is, anything near enough is good enough, be it mechanical, woodcase, called a number 2, or a HB, or a B, or a 2 ½, or a whatever. But as well as being too light, too dark and reflective can be a problem too.

Here’s a link to BIC mechanical pencils being tested and approved for Scantron tests.

Hey, here’s an idea, you know the wooden #2 pencil you got especially for the test, just like the teacher instructed? Well why don’t you ask the manufacturer to show you their approval for Scantron tests?

I went to the Scantron website and searched for “approved pencils”. The only specific result was BIC #2 MECHANICAL PENCILS. That’s right, according to that search, BIC mechanical pencils are the only pencils approved by Scantron themselves. Well, other than “Standard Number 2” pencils. Hey, here’s an idea, ask them what a “Standard Number 2” pencil is? Ummmm, a pencil with Number 2 written on it?

Bottom line, saying “Use a No. 2 pencil” is about as precise as saying “Write with ink”. Ummm, what colour ink? Gel or ballpoint? Is a fountain pen OK?

Addition: 29 August 2010 - here's a link to Pentel USA's blog where they guarantee their HB mechanical pencil as suitable for SAT bubble scan tests, etc.

Moving on, whats the .05mm or 0.7mm thing on mechanical pencils?
It’s the diameter of the lead, in millimetres, and its 0.5mm not .05, you’re working in millimetres not thousandths of an inch. The 0.5mm has got nothing to do with the pencil lead hardness or darkness, it’s how wide the lead is. Basically 0.5mm is fine writing, 0.7mm is a little wider and stronger also good for normal writing. Younger folk might be better off with 0.9mm or thicker as they are stronger again.


dodgemannfs said...

Just took one of those tests and used my graphgear 1000 with 2B leads because I thought the darker lead would be perfect for shading. Hope it works.

kiwi-d said...

Well you can report back how it went in due course :-)

Anonymous said...

I've used MP's for ALL my scantron tests so far, I think, using B and HB lead. I even think I did one in 4B once!

Matthew R said...

Very nice post, Dave. Well done.

Time Waster said...

Teachers don't know the difference between
hi-polyermer and a #2 pencils I think the pencil industry uses scare tactics thinking wood pencils are the only ones that are #2 Hb grade doesn't register unless teachers are smareter now days =) I went to school in the 80s so Mech Pencils were not very popular back then in the economy form.

Pop a point pencils were popular in Grade School also the ones with the bannana and orange scents.

Time Waster said...

I diskliked Scan tron test those things were rigged =) I would erase a spot and go over a different spot it wouldn't register on the new darkened areas so I would get it wrong.

Lazy teaching method

Anonymous said...

Hey, there really is a reason why #2 pencils are recommended - there are different kinds of lead used in pencils and some make a mark that does not absorb enough light to show up as a mark to the Scantron scanner. The machines work by reflective read. If the lead mark reflects too much light back to the light sensors in the machine, then it will not see it as a mark.

If you call Scantron Technical Support, most anyone who answers the phone can tell you what #2 pencil lead is and how it absorbs light in a way that best shows up to a Scantron machine - call them at 800-445-3141.

kiwi-d said...

Thanks Anonymous but I fell you are kind of missing the point. Scantron don't make pencils. The pencil manufacturers from China to Mexico to Malaysia to Germany all make widely varying leads and call them all #2.
Recommending #2 just means any old ordinary pencil - not an extra hard one nor an extra soft one.

@Rushi said...

m supposed 2 sit for a test in 2 days time n ws a little cofused..your post helped meh ou..thanx dave

Anonymous said...

I've done the PSATs and other california standardized testing sheets with a mechanical pencil. Never failed a test yet and I agree with the author, the wooden No.2 pencil requirement IS rubbish, backed by tradition and generations of stereotypes.

lekshmy said...


Sarah Urban said...

I watched a show, either "How It's Made," or some some show on Discovery that explained that the "recipe" used to make lead inside a wooden barrel is different than that used to make lead rods for mechanical pencils, and it's the recipe difference that accounts for varying degrees of lead deposits. Scantrons do NOT measure just a black blob else a black felt-tip pen would be ideal. It doesn't read black ball-point ink either. No ink. Just lead. It's the amount of shavings that get deposited as the black blob that get read. The mechanical pencils, according to the show I watched, put you somewhat at risk. Perhaps it is, to some degree, an "urban legend," perhaps mechanical lead is the same as wooden-barrel lead, but I wouldn't take chances myself. Many of you posted that you haven't "failed" a test using mechanical lead, but how--unless you can view each and every exam, which you cannot for national-type tests--do you know every bubble was counted correctly? How do you know you made the most accurate grade? Wooden pencils are cheap as hell, so why quibble? Just use the wooden one--from a well-known brand. Tixon, Mirado, etc. And happy testing to you.

kiwi-d said...

Yes, as discussed at length of this blog the recipe of mechanical pencil lead is different to woodcase pencil lead, but both use graphite as the marking substance. Anyway, as noted above in the article, the ONLY pencil specifically approved by Scantron is a mechanical pencil!

Arlette said...

Okay, i know mechanical has nothing to do with it (I've ALWAYS used BIC #2 Mechanical, and sometimes my teachers go over the tests w the class and it was accurate), my wonder is....what if it has no indication whatsoever? no #, no HB, no B, no ANYTHING. Reading this post and the comments, I'm confused now since they all seem to be contradicting eachother.

a nobud said...

A few months back, I took the olsat test which was on one of those #2 only forms and the teacher conducting it let us use any pencil to take it. Which proves A LOT.

Anonymous said...

does a 2b work on it? or 2h? iits a 2mm lead, but it has to work on this scantron.

Kiwi-d said...

2B yes, 2H might be getting a bit light, but if you pressed hard and made a good dark mark then yes. But why bother...just use HB, B, 2B, 3B.

Sapphire said...

I've been a freelance exam invigilator for over ten years and I've used all sorts of test equipment.
Scantron is just one of a number of companies making optical mark readers and forms for a variety of uses.
All the machines have their own little quirks but they all have one common aim - to recognise the marks placed there by the student (or whoever) and to ignore all of the other marks such as guidelines, instructions, question numbers or stray spiders.
They do this by comparing a dark mark against a light background and by ignoring certain colours, which is why the grids are printed in red or blue or turquoise.
They also ignore marks that are not the right shape so dashes need to be in the centre of the lines, bubbles need to be as near as possible completely filled in.
Raw graphite looks very much like new lead - grey and shiny. Soft pencils have more graphite than hard ones and although the mark is darker it is also shinier. This confuses some OMR machines and they might ignore the mark so don't go softer than 2B or 3B. Anything harder than H is likely to be too light.
Mechanical pencils tend to make finer lines than woodcased ones so you might need to go over the mark a couple of times to make sure the cell is adequately filled.
Most OMR machines will read ink marks but a few will assume they are part of the form and not read them.Maybe Scantron is one of them.
Also ink lines are not erasable. Some OMR machines will accept corrections to ink lines - usually using an X over the incorrect mark - but not all of them which is why pencils are advised.
I don't know why Time Waster's erasures went wrong. I can guess that may be your eraser damaged the paper to such an extent that the reader was confused and registered a double entry on those questions.
So just do as Dave says - use a medium pencil (mechanical or wooden) fill the cells in neatly and if you have to erase make sure your eraser is nice and clean.
Other than that stop worrying about pencils and make sure you do your revision :-)
Oh - and don't eat chocolate during the test - OMR machines CAN pick up chocolate crumbs.

Kiwi-d said...

Hi Sapphire. Thanks for yuor detailed comments, and good advice about the chocolate. Stick to jelly-babies for your mid-exam sugar rush :-)

ScanPRO said...

I've scanned hundreds of thousands of scan sheets over the past 15 years using Scantron OMR scanners with no problems. This month was the first time I came across a significant number of scan sheets on which marks were not being detected consistently. The school used #2 and HD pencils, and the marks were very dark and shiny. The only thing I have figured out so far is that the shiny marks were reflecting the light as if the bubble were empty. Perhaps the pencils were softer than #2...? When we wiped the marks with a damp cloth, they were read ok. We've now added a flagging routine to our software to detect if a significant number of responses are being left empty. Are any other OMR machine operators having this problem?

Kiwi-d said...

Hi ScanPRO - you say "the school used #2..." do you mean the school supplied the pencils - if so it would be interesting to know the brand(s). If the students just supplied and used their own #2 then I guess its impossible to work out and correlate if the problem relates to a particular brand/model of pencil.

ScanPRO said...

The school mailed me two different brand-name wood pencils that that the school supplied to students for the test. One was labeled #2; the other #2-HD. I tested them here, and found no problem with the marks being picked up. BUT I learned that some students used mechanical pencils. I'm following up on that by pulling the names of "top 20" students that had the greatest number of undetected responses on their scan sheets to find out what they used.

Kiwi-d said...

Hi ScanPRO,
Thanks for the update. If you have the time I'd appreciate you keeping us updated here.

Kiwi-d said...

Just one follow up - I note you write HD for the pencil. Is that what it says on the pencil or just a typo for HB?

ScanPRO said...

My mistake: The pencil said #2 - HB.
Also, I haven't heard back from the school yet. I'll post a comment if I find out anything new.

Anonymous said...

ScanPRO, don't know if you're still reading this, but one possibility occurred to me. Perhaps one or more teachers at that school instructed their students to fill in the bubbles as dark as they could. This misguided instructor could have thought, the darker, the better, so even students using #2 or HB pencils would make dark, shiny marks. Just an idea.

Sapphire said...

There is a point here about using mechanical pencils on Scantron bubble sheets or any other OMR that uses filled in shapes as opposed those using dashes across the centre of a cell.

Mechanical pencil lead tends to be finer so filling a cell needs more "scribbling" - rubbing the pencil back and forth or round and round. This, in turn, is likely to make the mark shinier and shiny marks can read as light so the machine reads them as not filled.

I'd be interested in the results.

Kiwi-d said...

Sapphire - point taken, but not if you keep your woodcase pencil sharp.

Anonymous said...

Mechanical Pencil leads will come to a 45 degree chisel point simply by scribbling with them twenty or thirty times, thus "priming" them for scantron tests. I will admit though that the chisel point is sometimes hard to find and you have to make a conscious effort to find it and this all but precludes 0.3mm leads as even the chisel point is too fine for scantrons. However 0.7mm and 0.9mm are ideal for this chisel point technique, with 0.5mm marginal.

Anonymous said...

hi, well i used black marker in all my examz. now i came to know that a pencil is preferred.. im very scared.. is black marker ok?

Anonymous said...

I used a .5 or.7 lead pencil on my scantron. Will the scantron be able to read it?

Kiwi-d said...

.5 and .7 are lead diameters.
The machine doesn't know or care how fat or thin, sharp or blunt, your pencil lead is.

Anonymous said...

I took a Scantron using a combination of a recycled pencil with no number and then went over it with a 4B sketching pencil and it read just fine. I knew they were lying. I was right. Thanks for the info!

Anonymous said...

Using a 2h 0.3 mechanical pencil , pushing it?

It's all i have

Roricka said...

I'm surprised no one from Scantron has jumped in here. My 2 cents: this conversation is leaving out an important issue, the Scantron scanner itself. We use an Insight 20 scanner (one of the newer Scantron scanners). We scan surveys that come from the military, typically someone working on a base in the US. Scantron told us to say "Use a No. 2 pencil or blue or black ink." Guess what? I get forms that have been marked with just about anything you can imagine. And I have NEVER had a form that didn't pretty much have all its marks picked up unless the respondent used something like red ink, which was invisible to the scanner. OK? So if you're worried, but you know the scanner is the Insight 20, then relax. Of course, who the heck knows which scanner model is being used? So, if I was someone's parent, and they were told use a number 2 pencil, yes, I would go out and buy 3 and sharpen them good. But honestly, has anybody ever heard of someone who got screwed because their mechanical pencil let them down on a Scantron test?

Vagabond On Move ... said...

Hi, Just wanted to know if in mechanical pencil all degrees of leads are available in all widths.

If yes, which company makes them?

Also, why do we have shine in shading when we are use these pencils.

How can the shine be avoided while sketching.

Dong Ho Kim said...

Hey guys i took an sat today (12/7/13) in New York, Freshmeadows, and i filled out the scantron in number 3 pencil. Will the machine give me accurate results?

roricka said...

Dong Ho Kim: were you told to use a number 2 pencil? Did you only have number 3 handy? As I wrote above, the chances are there will be no problem, but why chance it?

Architect of the Past said...

I can confirm that mechanical pencils are FINE for bubble in tests. Most of you are forgetting that someone who is not familiar in these fields and is new to the concept of all lead being pretty much the same wouldn't know the difference between HB, #2, 2B, 4B, 0.5, 0.7, (even 0.05) or anything else. They would just define all that as "Mechanical Pencil". They just want to know if the mechanical pencil they used instead of a "regular" pencil is okay. 99% of them are probably talking about 0.7mm HB lead. My normal pencil i use for standardized and school Scantron tests is the Pentel Graphgear 1000 with 0.5mm HB lead. To the person who said that you cannot be sure of the effectiveness of the pencil without viewing the bubble sheet after grading, I have viewed many of my tests given back from my teachers, and none of them has had any problem whatsoever with marking the pencil marks incorrectly. I regularly get 100% on Scantron tests, which would disprove the theory entirely of Scantron machines not picking up on mechanical pencil markings. I have also scored in the 2300's for SAT tests and gotten 800's for SAT II Subject Tests, which means mechanical pencils are good enough for those too. The way I bubble is on the first question, I will shade until I form the "chisel point" talked about earlier, then for the rest of the questions I will bubble until the circle is completely filled in to a reasonable degree, probably going over each individual spot 10 times at the most. So that's it. If you need more proof, the fact that BIC mechanical pencils are approved cannot be disputed; it is a fact.