Projected 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.
Easily confused with
How to read it
Usually a tolerance zone covers only the feature drawn. Keyence explains that a projected tolerance zone covers a virtual zone where the mating part will be. Cogorno’s guide gives the reason: in a threaded hole or a hole for a press-fit pin, the orientation of the hole sets the orientation of the stud or pin, so the zone is projected into the mating part. The height of the projected zone is equal to or greater than the thickest mating part, or the tallest stud or pin once installed (Cogorno). On the drawing the protrusion is shown with a chain line of a long dash and two dots (Keyence). Keyence’s list of symbols sums it up: the tolerance applies to the protrusion of a feature.
Also searched as: Ⓟ, projected tolerance zone gd&t, projected tolerance zone 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.
Where the symbol sits
Keyence describes the circled P written in the feature control frame with the length of the protrusion. The Illinois ME 170 notes, from an older edition, place the modifier below the frame and describe it for mating parts whose holes must line up.
Look-alikes
Other circled letters are modifiers too: Ⓜ, Ⓛ, Ⓕ and Ⓣ. Outside drawings, Unicode cross-refers Ⓟ (U+24C5) to ℗ (U+2117), the sound recording copyright symbol on music packaging.
Read next
- Next in GD&T symbolsFree state (Ⓕ)Ⓕ, a capital F in a circle, after a tolerance means the requirement applies to the part in its free state, under no force but gravity. It appears on drawings of flexible parts whose other tolerances are checked while the part is held in a restrained condition.
- 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
- What Is a Projected Tolerance Zone?, GD&T Fundamentals, KEYENCE America, What Is a Projected Tolerance Zone?
- 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 8, Position, Location, review answers
- 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
- GD&T Symbols, GD&T Fundamentals, KEYENCE America, Associated Symbols
- Enclosed Alphanumerics: Range 2460–24FF (code chart), The Unicode Standard, Version 18.0, Unicode Consortium, U+24C5
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research
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