This chart gives you fast access to all 14 tolerance controls, including, what each symbol means, how it looks on a drawing, what it controls, and when datums are required.
Here's how to read it.
Section 1
The main chart covers all 14 GD&T tolerance controls, organized into five categories based on what they control. Once you know which category a symbol falls into, you already know something about what it does.
Form Controls
Green rows · Straightness, Flatness, Circularity, Cylindricity
Control the shape of a feature by itself — no datums required. These form controls will never reverence any datums. These tolerances only care about the feature’s own geometry, not where it sits on the part.
Orientation Controls
Orange rows · Parallelism, Perpendicularity, Angularity
Control how a feature is angled relative to a datum. At least one datum is always required — these controls are meaningless without something to be parallel, perpendicular, or angled to. Orientation controls do not locate a feature; they only control its angle.
Profile Controls
Purple rows · Profile of a Line, Profile of a Surface
Control the shape of a surface or cross-section relative to a true profile. Profile of a Surface is one of the most versatile controls in GD&T — it can simultaneously control form, orientation, and location in a single callout. Datums are optional but common.
Location Controls
Yellow rows · Position, Concentricity, Symmetry
Control where a feature is located relative to datums. Position is the most widely used control in GD&T — it defines where a hole, slot, boss, or tab must fall within a tolerance zone (even controls spheres!). Datums are always required (unless youre controlling a pattern of features and dont care where that pattern ends up).
Note: Concentricity and Symmetry were removed from ASME Y14.5-2018. If you’re working to the 2018 standard, Consider using other controls like Position or Runout instead. Concentricity and Symmetry are still valid on drawings that reference an older revision — always check the title block.
Runout Controls
Red rows · Runout, Total Runout
Control how much a surface wobbles around a datum axis during rotation. Measured by spinning the part and inspecting the surface with a dial indicator. The go-to controls for shafts, bearings, and any rotating components.
Section 2
Each row of the chart is one tolerance control.
Every row gives you four things, and they build on each other left to right.
Column 1
This is your anchor. Every other column in the chart is explaining this one entry.
If you're starting from a symbol on a drawing, match it here first. If you're starting from a concept (like "I need to control how flat this surface is"), scan the names to find the right row.
Pay attention here: some symbols appear twice in this column — once applied to a surface and once applied to a feature of size. That distinction matters, because the same symbol means something different depending on how it's called out on a drawing.
Column 2
The geometry is simplified on purpose. The focus here is recognition: can you find this callout when it shows up on a drawing in front of you?
If a symbol appears twice in Column 1, it will appear twice here too. Once for the surface application, once for the feature of size application. The drawing will look different for each.
Column 3
The elements being controlled are shown in red: the feature or surface the callout applies to. The tolerance zone itself is shown in light blue: the invisible boundary the part must conform to.
The text alongside the graphic describes this in plain language. For example: "Controls surface elements to two parallel planes 0.03 apart." This is the translation from symbol to meaning. What an inspector is actually measuring when they check this callout.
Column 4
Check out the right side of this chart to reference the foundations of the Maximum Material Condition Modifier (MMC) and the Least Material Condition Modifier (LMC).
If you're not sure what those symbols mean, the right side of the chart has a reference section for exactly that.
The Right Side of the Chart
Here you'll find the material condition modifiers MMC and LMC, which unlock bonus tolerance and are essential to understanding how GD&T interacts with part size.
You'll also find the datum feature symbol and datum targets, which are the building blocks of any measurement reference frame.
Rounding it out are a handful of specialized modifiers and symbols — including Projected Tolerance, Free State, Tangent Plane, Independency, and more — each of which changes how a tolerance is interpreted or applied in specific situations.
Whether you're decoding a drawing you've never seen before or double-checking your own callouts, this section gives you quick access to the context you need to get it right.
