The Complete Guide to Mechanical Pencil Lead Grades

Do Mechanical & Wooden Pencils Have the Same lead Grades?

Mechanical pencils have fewer lead grades to choose from than wooden pencils because they have thinner lead.

This guide explains the difference between mechanical pencil lead and wooden pencil lead, how mechanical pencil lead is made, the mechanical pencil lead grade scale, the darkest mechanical pencil lead, and much more.

If you want to know more about colored lead for mechanical pencils then check out the Ultimate Guide to Colored Mechanical Pencil Lead for more information.

The Complete Guide to Mechanical Pencil Lead Grades

1. Mechanical Pencil Lead Vs Wooden Pencil Lead

The lead core of a wooden pencil is approximately 2 mm in diameter. Mechanical pencils are usually a lot thinner, typically 0.3 mm to 0. 9 mm in diameter.

Because the lead is so thin, it means that the lead is manufactured differently from that of wooden pencils, and also, there are fewer lead grades available.

The pencils lead also writes slightly differently due to the different materials used to make the core.

Check out our Ultimate Guide to Mechanical Lead Sizes for more information on the different sizes.

2. What is Mechanical Pencil Lead Made of?

Mechanical pencil lead is fragile compared to wooden pencil lead, and it is made from different materials to make it stronger and prevent it from breaking.

Wooden pencil lead is made from a combination of clay, graphite, grease, or wax.

  • The clay binds the graphite and other materials together, and the graphite leaves a visible mark on the paper.
  • Grease or wax lowers the friction between the lead core and the paper’s surface.

Check out What is Pencil Lead Made of? for more information about wooden pencil lead.

The downside of this type of lead is that it is not very strong, but it does not matter too much as it is significant in diameter (approximately 2 mm).

The lead is also bonded with glue to the pencil protective outer wooden case to add strength and prevent breakages in a wooden pencil.

To compensate for the lead not being very strong, the lead diameter of the first mechanical pencils was around 0.9 mm.

This changed in 1962 when Pentel launched two new mechanical pencils with 0.7 mm and 0.5 mm lead diameters.

These Pencils had a new type of lead called Super High Polymer Lead.

The main difference between these leads and wooden pencil leads is that a polymer replaced the clay as a binder for added strength.

Pentel AIN STEIN Framework Strength

As you can see from the diagram above, it shows how the silicon polymers give their Pentel AIN STEIN Lead its added strength.

The other pencil manufacturers followed suit with Faber-Castell introducing in 1967 a 0.5 mm mechanical pencil with 0.5 polymer lead.

Staedtler followed them in 1967 with the introduction of their own 0.5 mm pencil and polymer lead refills.

Check out our Ultimate Guide To The Best Mechanical Pencil Lead for more information on Pentel AIN STEIN and the other top lead brands.

3. Mechanical Pencil Lead Hardness Scale

The main difference between the mechanical pencil lead hardness scale and the wooden pencil lead grade scale is that there are fewer grades available due to the thinness of the lead compared to a wooden pencil lead core.

Mechanical Pencil Lead Hardness Scale

Instead of 24 Grades from 10H – 12B, there are only ten grades from 4H -4B

The mechanical pencil lead grade scale uses precisely the same values H (hardness) & B blackness) as the standard pencil lead hardness scale.

These are combined with a number to represent how hard or soft the pencil lead is.

With H grades having harder lead and writing a light grey color

And B grades having a softer lead that writes a darker black color.

4. The Hardest Mechanical Pencil Lead

4H is the hardest mechanical pencil lead grade. It is used for drafting and technical drawing. It is not a popular grade; therefore, manufacturers only make it for 0.5 mm mechanical pencils.

Pentel, Pilot, and Uni are the three leading manufacturers that make 4H lead refills.

5. The Softest Mechanical Pencil Lead

The softest mechanical pencil lead grade is 4B because of the thin diameter of mechanical pencil lead compared to wooden pencil lead.

If the lead were any softer, i.e., 6B, it would be unusable as it would be too soft to work in a mechanical pencil without breaking.

6. The Darkest Mechanical Pencil Lead

Pilot Neox Graphite Lead

Buy on Amazon

The Darkest Mechanical lead grade is 4B, with Pilot Neox Graphite lead being highly recommenced online for being particularly dark compared to the other lead brands.

7. The Strongest Lead For Mechanical Pencils

The strength of pencil lead increase with the diameter of the pencil size, i.e., 0.7 mm lead has a greater diameter than 0.5 mm lead and is, therefore, more robust.

Pentel AIN STEIN Lead

Buy on Amazon

Regarding which brand of mechanical pencil lead is the strongest, Pentel AIN STEIN is widely regarded as the most robust mechanical pencil lead compared to the other brands.

8. 8B Mechanical Pencil Lead

As we have already seen, the softest mechanical pencil lead grade is 4B and is only available for 0.5 mm pencils.

Clutch pencils or lead holders are a particular type of mechanical pencil that takes 2.0 mm lead refills.

Koh I Noor 2 mm 8B Lead Refills

Buy on Amazon

Koh_Noor is the only company I know that makes 2.0 mm 8B lead for mechanical pencils.

9. Mechanical Pencil Lead Grade Indicator

General-purpose writing pencils usually don’t have a lead grade indicator with just the lead diameter marked on the barrel or cap.

However, drafting pencils are pretty likely to have a lead grade indicator built in the cap.

Drafters are likely to have several of the same make of pencil with different lead grades in them.

A lead grade indicator helps them to quickly identify which grade of lead is fitted to the pencil.

2 thoughts on “The Complete Guide to Mechanical Pencil Lead Grades”

  1. Old mechanical pencils I have do NOT have the lead diameter noted. How do I determine size when it is time to refill? Do I need a micrometer? Can I try to push the lead into the orifice the and if it fits, I am good to go?

    Reply
    • I would try and gently push a lead that you think is the correct size slowly gently back up in the lead sleeve as the correct size should be a good fit. too big and it will not go, too small and it will be too loose. check out our guide to mechanical lead sizes for more info.

      Reply

Leave a Reply to Daniel Cancel reply