The answer varies widely by manufacturer. In this scale from Wikipedia, the pencil known as a Number 2 is also known as an HB, a middle grade of pencil. It has less graphite and more clay than a B and the 2B through 10B. It has more graphite and less clay than the H and therefore 2H through 10H.
Henry Petroski , in his Pencil book, claims that pencil grades vary “depending upon the manufacturer, when the pencils are made, and the source of graphite and clay. One analyst found that graphitic carbon content, for example, to vary from about 30 to about 65 in a variety of different pencils bearing the same designation.
The Number 2 pencil is the standard for test taking and writing, and is the most commonly available pencil. Pencils that are not marked with a grade, like promotional pencils or fun giveaway pencils are also likely within the acceptable range of graphite levels.
School pencils in the 21st century in the United States are most commonly the Dixon Ticonderoga, as teachers are now asking for them by name. And sometimes, teachers even require that each student supply 50 pre-sharpened Dixon Ticonderoga pencils! One assumes that not all students can or do comply, or that the teacher is doing a lot of writing during the summer.
These pictures show a wide variety of #2 school pencils –
– as well as other HB pencils, including brands from other countries, or ones that belong to drawing sets.
I separated out the yellow/orange ones, which take their color cue from the Koh-i-noor pencils, and have become the de-facto color for school pencils. In fact the yellow pencil is a symbol for schools and learning.
I have covered many other pencil sets in previous posts that have HB pencils not pictured here.
As you can see by these samples on Strathmore drawing paper, the pencils lay down graphite in a noticeably wide range.