Why are pencils number 2? Thoreau’s grades, a missing standard and a yellow coat of paint
The 2 on a No. 2 pencil is a hardness grade. American pencils are graded by number, and the higher the number, the harder the core and the lighter the line. A No. 2 sits in the middle: dark enough to read, hard enough to keep a point. What most people do not know is that the number has no fixed meaning. One brand’s No. 2 is not the same as another’s.
What the numbers mean
A pencil “lead” is a mix of graphite and clay. More clay makes a harder core that leaves a lighter mark, and less clay makes a softer, darker one that wears down faster. Pencils.com, a pencil seller that calls itself “the cedar pencil experts”, explains the two grading systems in use. In the United States pencils carry a number such as 2, 2½ or 3, and the higher the number, the harder the core. Most makers outside the US use letters instead: H for hard, B for black, F for a core that sharpens to a fine point, and combinations with numbers such as 2B or 3H.
A US No. 2 is generally treated as the equivalent of HB, the middle of the letter scale. But the same page adds the part that surprises people: “there is no specific industry standard for the darkness of the mark to be left within the HB or any other hardness grade scale.” Each manufacturer sets its own internal standard, so a No. 2 or HB from one brand will not necessarily leave the same mark as one from another. Regional taste plays a part too. According to Pencils.com, Japanese buyers prefer softer, darker leads, so a Japanese HB is generally darker than a European one.
The numbers go back to Thoreau
The idea of grading American pencils by hardness is tied to the family of Henry David Thoreau, better known for Walden. His father, John Thoreau, went into the pencil business in 1823. In an essay for The American Scholar in 2024, the historian Augustine Sedgewick writes that in 1837 Henry developed a formula for kiln-fired leads, “a mix of finely ground graphite and clay”, that could be “reliably graded from hard to soft”, and that in 1844 he invented a machine that ground graphite into an exceptionally fine powder. Thoreau pencils won awards in 1847 and 1849.
The family numbered its grades from one to four, and this is usually credited as the origin of the American habit of numbered pencils. The business did not last long enough to see the No. 2 become a school staple. By 1853 J. Thoreau & Son had left pencil making, and Sedgewick notes that the family’s cedar came from southern states, particularly Florida, where it was cut by enslaved workers.
Why No. 2 won the classroom
The middle grade was the practical choice for writing: soft enough to read easily, hard enough not to smudge or need sharpening every few lines. Standardised tests made the habit stick, because answer sheets asked for a No. 2. Even there the rule was looser than it sounds. Mental Floss, writing about SAT answer sheets, reports that the general consensus is that the scanners read a No. 3 mark just as well as a No. 2.
And why they are yellow
The yellow comes from a marketing coup. At the 1889 World’s Fair in Paris, the Hardtmuth company of Budweis, in Bohemia, launched a premium drawing pencil called Koh-i-Noor, after the famous diamond. Caroline Weaver, writing on the CW Pencils blog, says that the Koh-i-Noor 1500 came in 17 grades, “unheard of at the time”, and was finished in coats of yellow lacquer with a gold-dipped end. Accounts differ on how many coats and how many carats.
Why yellow is less certain. The usual explanation is that the best graphite of the day came from China, where yellow was associated with royalty, so the colour signalled both the source and the quality. Others link it to the yellow of the Austro-Hungarian flag. Either way, the pencil was a hit and American makers painted their own pencils yellow to look like it. According to Henry Petroski’s history The Pencil, about a hundred years later roughly three out of four pencils made were yellow.