9 reasons why engineers use H-type pencils

Why do engineers use H-type pencils for drawing, do they have something special?

In this article, we’re going to discover 9 reasons why engineers use H-type pencils for drawing.

H types are less darker

firstly we have to understand the pencils classification, pencils are classified into 3 categories:

H type pencils from H to 10H ==> (1H,2H,3H,4H,5H,6H,7H,8H,9H,10H)
F fine pencils (1 single model)
HB pencils (1 single model and the most usable)
B type pencils from B to 12B (1B,1B,2B,3B,4B,5B,6B,7B,8B,9B,10B,11B,12B)

So we have 24 pencils grades each one is different from the other. you can watch this table below to see the difference between each one.























ligher + harder<====>softer + darker

10H <====HB====>10B

The more H value increases the more pencil head are harder and has lighter color. and the more B value increases the more pencil is softer and blacker.

for instance, 10H is way lighter and harder than 1H. Also, 10B is way darker and softer than 1B.

To resume

H = Hardness

B = Blackness

2H is harder than H

2B is softer and darker than B


According to Penvibe, standard pencils like HB have 26% clay and 68% of graphite. For instance, if we take 8B one of the most blacker and softer pencils we find 90% of graphite and 4% clay.

But if we go and look for the finest and lighters pencil-like 8H we get 44% of graphite and 50% of clay. So the more graphite and fewer clay pencils have the more are darker and softer, and vice versa.

Engineers use H-type pencils because they have less clay and less graphite in their composition, this is what makes the scratchy consistent of a pencil head. As result allow it ensure good adherence to paper and avoid slippery movements.

Drawing fine line and more detailed drawings

H-type pencils are known for their toughness which makes them good for drawing fine lines. This becomes so helpful for architectures who tend to draw vertical and horizontal straight lines.

There is a good option to use for drawing straight lines using rules. But finner ones like 0.5mm or less such as 0.3mm require specific care because they easily break out. Also, they could go through the paper, not like broader heads like 0.7 mm or 0.9mm.

Are not smdugy

H-type series of pencils begin from 1H to 10H, they are lighter and not smudgy. For instance, if we compare between 10H and 1H we could guarantee that 10H pencils are impossible to get smudged.

10H is extremely lighter, 1H is 10 times darker than 10H. The 10H is very light. So they don’t create dark stains that could smudge the paper.

But if take the darkest pencil version like 10B, is almost black once you put your finger on the paper you get easily stained. 10B has 95% of graphite which is responsible for the dark color.

H types are for engineers and B for writers and artists

According to lisbdnet 2 billion pencils are used by individuals in the USA each year. So pencils are used widely by a variety of students. Students use every year between 20 to 30 pencils, which is a lot. The principal reason is students don’t know that pencils are divided into two categories and have different sizes.

pencils have two types H type and B type.

H type is made for engineers who seek accuracy and good adherence. B type is made for artists and writers who love shading smothenes drawing and dark colors. It is very hard to use H pencils for drawing especially when it comes to coloring.

In other words, if you want to color some spot it will take a lot of time and pencils get rapidly consumed. they have a little amount of graphite, engineers use them only if they want to draw some finner and lighter color lines.

Thus for artist students using H-type pencils will be not effective. it will consume a lot of time for sketching and continuously need to be sharpened every while, which decrease significantly its life span.

The second thing that students don’t know, is pencils have a variety of lead heads. They vary from 0.3 mm to 2 mm so choosing the right pencil head is a determinant factor.

Easier correction

As we noticed in our color table, H-type pencils are approximately 10 times lighter than B types versions. Consequently makes them easy to correct, hence engineers love use them. Drawing lighter color and finner lines makes them easy to be erased.

In other words, they are easier to erase compared to the darkest pencil colors. deleting completely the dark pencil writing is almost impossible, stains always remain and make the paper smudgy which is unacceptable for engineers.

It is noticeable more for architect engineers who draw straight lines, these lasts get easily through paper and make them very hard to erase.

Don’t require a lot fo pressure

According to Recharge human finger force vary between 30N to 110N for more trained and tougher persons. 30N means being able to hold 3.64 kg with one finger or push through a surface with 3.64kg weight. hence humans can hold pens for long times.

But which is the good type of pen to hold for a long time? H type has this advantage because they don’t require a lot of pressure to write or draw. H type is such fountain pens there is no pressure to exert to them they flow easily.

smoothness is the principal reason why teachers love to use fountain pens. while engineers love the scratchiness that the H-type pen has, which makes the best adherence and requires less pressure for sketching.

More accurate

H-type pencils are more accurate this is why engineers use them to draw along rulers. Most engineers use 0.7 mm H type pencils, they are good and not prone to break out like 0.5mm or less such as 0.3mm.

For mechanical design, accurate pencils are important, simply because mechanical models have a lot of details. Also, respecting sizes create the best impression about the products engineers would manufacture.

Accuracy could not be important in the art field, but in engineering, millimeters could be the different between failure and success of the product.


If we compare the extreme lead degrees of H-type pencils and B-ones, we will find that
H-type pencils have 10 times more clay than B Types. This is the secret that makes H types pencil hard to break, the portion of clay is high on its composition.

Also, H type pencils have less graphite by 50%, graphite is known by it hardness but it easily breaks out. So reducing the graphite quantity increase its flexibility and make it hard to break.

H pencils are stronger because they have less amount of graphite and high portion of clay. This balance increases the head pencil resistance.


engineers use H type pencils because they know its ability and form what is made. According to the 9 reasons that we noticed in our article H type pencils are a great choice for engineers while B type is the favorite and effective for artist shadowing and coloring.

But currently, a lot of engineers use mechanical pencils such as the latest version in the market. you can watch this video below.

while some others use draft pencils they are more flexible you could watch this video about draft pencils.


Yassin ajanif is a physics graduate and electromechanical engineer width more than 5 years in the field. My goal and my team are to share our experience to help you succeed in your career as a stem major. we talk about all tips, problems, and struggle STEM students face in their career and how to overcome them.