GD&T Symbols Chart (ASME Y14.5)
All geometric characteristic symbols with category, datum requirement and a plain-English meaning, flagged for the 2018 withdrawal of concentricity and symmetry, plus the modifier symbols.
- Tables
- 3
- Rows
- 35
- References
- 5
- Revised
- 2026-08-11
Geometric characteristic symbols
14 rows
| Symbol | Characteristic | Category | Datum required | ASME Y14.5-2018 | Meaning |
|---|---|---|---|---|---|
| ⏤ | Straightness | Form | No | Current | Keeps a surface line, or the feature's own axis, from bowing — it must stay inside a straight zone of the stated width. Says nothing about where the feature sits. |
| ⏥ | Flatness | Form | No | Current | Every point on the surface has to fall between two parallel planes set the tolerance apart. Self-contained: no datum, and no relationship to any other face. |
| ○ | Circularity (roundness) | Form | No | Current | Slice the feature perpendicular to its axis and the outline of that one slice must sit between two concentric circles whose radii differ by the tolerance. Each slice is judged on its own. |
| ⌭ | Cylindricity | Form | No | Current | The whole cylindrical surface must fit between two coaxial cylinders separated by the tolerance. One control that simultaneously limits roundness, straightness of the axis, and taper. |
| ⌒ | Profile of a line | Profile | Optional | Current | A single cross-sectional outline must stay inside a two-dimensional band that hugs the theoretically exact shape. Checked one slice at a time, so it does not police the surface as a whole. |
| ⌓ | Profile of a surface | Profile | Optional | Current | The entire surface must lie inside a three-dimensional shell wrapped around the ideal shape. The most powerful symbol in the set — with datums it can control size, form, orientation and location at once. |
| ∠ | Angularity | Orientation | Yes | Current | Holds a surface or axis at a stated basic angle to a datum. It fixes the tilt only; where the feature sits along the part is left to other controls. |
| ⊥ | Perpendicularity | Orientation | Yes | Current | Holds a surface or axis square to a datum. Mathematically just angularity at 90°, so no basic angle is written. |
| ∥ | Parallelism | Orientation | Yes | Current | Holds a surface or axis the same distance from a datum along its whole length. Angularity at 0° — again, no basic angle is written. |
| ⌖ | Position | Location | Yes (usually) | Current | Limits how far a feature's center, axis, or median plane may wander from the exact spot defined by basic dimensions. The workhorse control for hole patterns and the correct replacement for concentricity and symmetry. |
| ◎ | Concentricity | Location | Yes | Withdrawn | Required the median points of opposing surface elements to hug a datum axis. Withdrawn in ASME Y14.5-2018 — the median-point derivation is slow and poorly repeatable to inspect. Use position or runout. |
| ⌯ | Symmetry | Location | Yes | Withdrawn | Required the median points of a feature to straddle a datum plane evenly. Withdrawn in ASME Y14.5-2018 for the same measurement difficulty as concentricity. Use position. |
| ↗ | Circular runout | Runout | Yes | Current | Spin the part about its datum axis and, at any one fixed cross-section, the indicator sweep must stay inside the tolerance. Catches roundness plus off-center position together, in one cheap measurement. |
| ⌰ | Total runout | Runout | Yes | Current | Same rotation, but the indicator travels the full length or across the whole face while the part turns. The entire surface must stay within a single tolerance band, so it also catches taper and profile error. |
| No rows match that filter. | |||||
14 rows × 6 columns
Category summary — ASME Y14.5-2018 against Y14.5-2009
| Category | Count (2018) | Count (2009) | Members | Datum |
|---|---|---|---|---|
| Form | 4 | 4 | Straightness, Flatness, Circularity, Cylindricity | Never |
| Profile | 2 | 2 | Profile of a line, Profile of a surface | Optional |
| Orientation | 3 | 3 | Angularity, Perpendicularity, Parallelism | Always |
| Location | 1 | 3 | Position — concentricity and symmetry withdrawn in 2018 | Usually |
| Runout | 2 | 2 | Circular runout, Total runout | Always |
| No rows match that filter. | ||||
5 rows × 5 columns
Modifiers and supplementary symbols
16 rows
| Symbol | Name | Meaning |
|---|---|---|
| Ⓜ | Maximum Material Condition (MMC) | Apply the tolerance at the feature's most-material size; bonus tolerance is earned as the feature departs from MMC. Use for assembly clearance. |
| Ⓛ | Least Material Condition (LMC) | Same bonus mechanism anchored at the least-material size. Use to protect wall thickness or edge distance. |
| (none) | Regardless of Feature Size (RFS) | ASME default with no modifier: tolerance applies at every size, no bonus. |
| Ⓟ | Projected tolerance zone | Moves the tolerance zone into the mating part, typically above a tapped hole. |
| Ⓕ | Free state | Inspect unrestrained; for non-rigid parts. |
| Ⓣ | Tangent plane | Control the plane resting on the high points instead of every surface point. |
| Ⓤ | Unequally disposed profile | Profile zone split unevenly about true shape; outward amount stated after the symbol. |
| Ⓘ | Independency | Releases the envelope requirement so form is not limited by size. |
| ⟨ST⟩ | Statistical tolerance | Valid only under statistical process control. |
| ⟨CF⟩ | Continuous feature | Treat interrupted surfaces as one feature. |
| △ | Dynamic profile | New in Y14.5-2018; profile zone controls form only and may expand/contract uniformly. |
| ⌀ / S⌀ | Diameter / spherical diameter | Declares a cylindrical or spherical tolerance zone or dimension. |
| R / CR / SR | Radius / controlled radius / spherical radius | CR requires a fair curve with no flats or reversals. |
| ▷ | Translation | Datum feature simulator is free to translate rather than being locked. |
| ↔ | Between | Applies the tolerance only across the stated span. |
| Ⓔ | Envelope requirement (ISO) | ISO-only; imposes the envelope condition that ASME applies by default. |
| No rows match that filter. | ||
16 rows × 3 columns
Basis and references
The widely repeated "14 geometric characteristic symbols" figure is out of date. It comes from ASME Y14.5-2009. ASME Y14.5-2018 removed concentricity and symmetry, reducing the set to 12. Both are still listed below and clearly flagged, because they remain on a large amount of legacy drawing stock and inspectors still have to read them — but neither should appear on a new drawing. The replacement in both cases is position, or runout for coaxial features.
The symbols split into five categories. Form controls (4) never take a datum: they describe a feature against itself. Profile controls (2) may take a datum. Orientation (3) and runout (2) controls always take one. Location now has a single member, position, where it had three in 2009.
The plain-English meanings in the table below were written for this site. The category assignments, datum requirements and 2018 statuses are factual and were verified across five independent sources.
References
- [1]GD&T Basics — GD&T Symbols Explained: Full Reference Guide
- [2]GD&T Basics — ASME Y14.5 2009 vs. 2018: Standard Changes
- [3]Mitutoyo — GD&T and the new ASME Y14.5-2018 (Salsbury)
- [4]GeoTol — ASME Y14.5-2018 vs. 2009: Changes & Latest GD&T Standards
- [5]Measure Metrology — ASME has just released Y14.5-2018: what's new?
Every value on this page was set against at least two of these sources and recomputed rather than transcribed. Where they disagree, the disagreement is recorded in the notes below.
Revision and twin
Last reviewed . This page carries 35 rows across 3 tables, all of them in the HTML — nothing is paginated, gated or fetched.
Plain-Markdown twin: /charts/gdt-symbols.md
Notes to the tables
5 notesWhere this data disagrees with itself, with other published charts, or with what the number looks like it means.
Concentricity and symmetry were withdrawn in ASME Y14.5-2018. Four independent sources confirm it. Both required deriving median points from opposing surface elements, which is slow and poorly repeatable to inspect. Use position instead, or runout for coaxial features. Symbol reference pages that still list all 14 without flagging the withdrawal are how the outdated count keeps propagating.
Counts reconcile: 4 + 2 + 3 + 3 + 2 = 14 under Y14.5-2009, and 4 + 2 + 3 + 1 + 2 = 12 under Y14.5-2018.
Dynamic profile (△) is a Y14.5-2018 addition, confirmed by two sources. The profile zone controls form only and is free to expand or contract uniformly, so size and location are handled elsewhere.
Several GD&T symbols have no exact Unicode codepoint — all-around, all-over, the datum feature symbol, and the runout arrows in particular. The characters shown here are the closest available and are adequate as database keys, but they are approximations of the drawn glyphs, not the glyphs themselves.
Not verified against the standard document itself. ASME Y14.5-2018 is paywalled; all verification here is against secondary sources, four of which are independent and in agreement.
Questions
8 questionsHow many GD&T symbols are there?
Twelve geometric characteristic symbols under ASME Y14.5-2018. The commonly quoted figure of 14 is from Y14.5-2009; the 2018 revision withdrew concentricity and symmetry.
Why were concentricity and symmetry removed from ASME Y14.5?
Both required deriving median points from opposing surface elements, which is slow to measure and poorly repeatable. Y14.5-2018 withdrew them. Use position instead, or runout for coaxial features. They still appear on legacy drawings, so they are listed here flagged as withdrawn.
Which GD&T symbols need a datum?
Orientation (angularity, perpendicularity, parallelism) and runout (circular, total) always need one. Form controls (straightness, flatness, circularity, cylindricity) never take one. Profile controls may take one. Position usually does.
What is the difference between circular runout and total runout?
Circular runout judges the indicator sweep at one fixed cross-section as the part rotates. Total runout moves the indicator along the full length or across the whole face while the part turns, so the entire surface must fall inside a single tolerance band — which also catches taper and profile error.
What does the MMC modifier do?
Maximum Material Condition applies the tolerance at the feature's most-material size — the smallest hole or largest shaft — and grants bonus tolerance in proportion as the feature departs from that size. Use it when the concern is assembly clearance.
What is the default if no modifier is shown?
Regardless of Feature Size (RFS). The stated tolerance applies at every size with no bonus. It is the ASME default and needs no symbol.
What is profile of a surface used for?
It is the most powerful control in the set: the whole surface must lie inside a three-dimensional shell wrapped around the ideal shape. Combined with datums it can control size, form, orientation and location simultaneously.
What is dynamic profile?
A Y14.5-2018 addition. The profile zone controls form only and is free to expand or contract uniformly, so size and location are left to other controls.
How to cite this page
Manufacturing Processes. “GD&T Symbols Chart (ASME Y14.5).” manufacturingprocesses.org, last reviewed 2026-08-11. https://manufacturingprocesses.org/charts/gdt-symbols
If you reproduce a table, cite the standard it derives from as well — the references are the primary sources, this page is a cross-checked transcription of them.