Mechanical Pencil Leads

Direct Answer

Mechanical Pencil Lead Sizes (standardized under ISO 9177-2) define polymer-bonded graphite refill diameters: 0.2 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, and 2.0 mm leadholders, with a standard length of 60.0 mm. Sized for specific drafting and handwriting pressures, 0.5 mm is the universal drafting standard and 0.7 mm is the heavy-pressure writing standard.

Source: ISO 9177-2:1989 (Mechanical pencils — Part 2: Black leads — Classification and dimensions) / JIS S 6005 · Last reviewed Aug 28, 2026

Specs

0.2 mm Lead (Pentel Orenz)	0.20 mm — ultra-micro drafting and mathematical annotation (requires sliding guide pipe)
0.3 mm Lead (Drafting)	0.35 mm actual diameter — technical engineering drafting, complex kanji, fine stippling
0.5 mm Lead (Universal)	0.50 mm actual diameter — the global standard for students, drafting, and office writing
0.7 mm Lead (Heavy Pressure)	0.70 mm actual diameter — robust everyday writing, resists snapping under heavy hand pressure
0.9 mm Lead / 1.3 mm Lead	0.90 mm to 1.30 mm — woodworking carpentry, standardized test bubble filling, primary school
2.0 mm Leadholder (Clutch Pencil)	2.00 mm diameter × 130 mm length — architectural sketching, requires rotary lead pointer sharpener
Standard Refill Length	60.0 ± 1.0 mm (for 0.2 mm to 0.9 mm polymer high-polymer leads)

Polymer Lead Revolution

Traditional wooden pencil leads use ceramic-clay binders fired at high heat, which are brittle and snap easily below 2.0 mm. Modern thin leads (0.2 mm to 0.9 mm) use high-polymer synthetic resin binders (invented by Pentel in 1962), infusing graphite with polymers and lubricating oils to achieve high tensile flexural strength at microscopic diameters.