Least material condition (Ⓛ)
Ⓛ, a capital L in a circle, is the least material condition modifier: the tolerance applies when the feature holds the least material, the largest hole or the smallest pin, and grows as it departs from that size.
Easily confused with
How to read it
Least material condition is the opposite end of the size range from maximum material condition: the smallest size of an external feature and the largest size of an internal one (Illinois ME 170 notes; Berez, UNC Charlotte; Cogorno). Keyence describes what it is used for: controlling the size and position of holes together with the thickness of the material around them, since a hole at its largest size placed close to an edge leaves the thinnest wall. In Keyence’s example, a position tolerance of Ø0.5 with Ⓛ applies when the Ø24 hole is at its least material size of Ø24.1, and the tolerance grows as the hole gets smaller.
Also searched as: Ⓛ, least material condition gd&t, least material condition symbol, lmc, lmc symbol.
This explains what a symbol specifies on a drawing. It isn't inspection or design guidance; the drawing and the edition of the standard it cites take precedence.
Editions
The engineering drawing notes used in Illinois’s ME 170 course, written to an older edition of the standard, say only the MMC modifier was called out in the frame and LMC was a reference value with no modifier. Current guides from Cogorno and Keyence treat Ⓛ as a modifier in the frame.
Look-alikes
Maximum material condition Ⓜ is the circled M. Unicode encodes this symbol as Ⓛ (U+24C1) CIRCLED LATIN CAPITAL LETTER L.
Read next
- Next in GD&T symbolsProjected tolerance zone (Ⓟ)Ⓟ, a capital P in a circle, means the tolerance zone is projected out of the part over a stated height, above a threaded or press-fit hole, instead of lying inside the hole.
- The same shape in AI labels and iconsAI iconAI-generated or AI-changed content. A badge with the letters AI, often in a circle or beside a word such as generated or modified, labels an image, video, sound or text as made or altered with artificial intelligence. The European Union publishes an official set of these icons.
More GD&T symbols
The same shape elsewhere
Browse symbols drawn with circles or letters and numbers.
Sources
- Fundamentals of Geometric Dimensioning and Tolerancing (GD&T), Part I, Jaime Berez, seminar adapted from an undergraduate mechanical engineering course, version 2.1.0, 2023, Center for Precision Metrology, University of North Carolina at Charlotte (Zenodo), Slide 45
- Engineering Drawing Notes, Unit 8: Terms and Symbols (Part C, Geometric Dimensioning & Tolerancing), ME 170, fall 2019, Grainger College of Engineering, University of Illinois Urbana-Champaign, Unit 8, Supplementary symbols
- Geometric Dimensioning and Tolerancing for Mechanical Design: Instructors’ Guide, Gene R. Cogorno, guide to the McGraw-Hill textbook, rev. 10/12/2020, Technical Training Consultants, Chapter 3, review answers
- Least Material Condition (LMC), GD&T Fundamentals, KEYENCE America, Using Least Material Condition
- Enclosed Alphanumerics: Range 2460–24FF (code chart), The Unicode Standard, Version 18.0, Unicode Consortium, U+24C1
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research
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