Pencil leads are the consumable core of mechanical pencils, providing a continuous writing or drawing experience without the need for sharpening. These slender graphite or polymer rods are designed to be fed incrementally from the pencil's mechanism, offering a consistent line width and density. They are widely used in academic settings for note-taking, in professional environments for drafting and technical drawing, and by artists for sketching and detailed work. The convenience of a mechanical pencil, coupled with the readily replaceable leads, makes them a practical choice for tasks requiring precision and a clean output.

Within the category of pencil leads, two primary subtypes are commonly encountered: "Compass Mines" and "Pencil leads." Compass Mines are specifically engineered for use in compasses, often featuring a slightly thicker diameter and a robust composition to withstand the rotational forces and pressure applied during geometric constructions. Standard "Pencil leads," on the other hand, encompass the broader range of leads designed for general-purpose mechanical pencils, available in various diameters and hardness grades to suit diverse applications.

When selecting pencil leads, several properties are important to consider for optimal performance. The lead diameter, typically ranging from 0.3 mm for fine detail to 2.0 mm for bolder lines, dictates the line thickness. The hardness grade, indicated by a letter and number system (e.g., HB, 2B, H), determines the lead's darkness and resistance to smudging. Softer leads (B grades) produce darker lines and are often preferred for artistic endeavors, while harder leads (H grades) offer lighter, more precise lines suitable for technical drawing. Customers can utilize these properties to filter and identify the ideal leads for their specific needs.

Several manufacturers offer a wide array of pencil leads. Faber-Castell provides the 9071, a reliable option for everyday use. Pica offers refill leads, catering to their specialized marking tools. Caran d'Ache produces Technograph refills, known for their smooth writing characteristics. Pentel's Ain Stein leads are recognized for their strength and resistance to breakage. Staedtler offers the Mars micro carbon 255 lead, available in various diameters and hardness grades, including the 0.5 mm HB, a popular choice for general writing and technical drawing. more