GD&T — Cheat Sheet
The 14 controls, modifiers, bonus tolerance and virtual condition on a page.
The 14 controls
| Form (no datum) | straightness — · flatness ⏥ · circularity ○ · cylindricity ⌭ |
| Orientation | perpendicularity ⟂ · parallelism ∥ · angularity ∠ |
| Location | position ⌖ · concentricity ◎ · symmetry ⌗ |
| Profile | line ⌒ · surface ⌓ |
| Runout | circular ↗ · total ↗↗ |
Modifiers
| Maximum material | Ⓜ (MMC) — bonus tolerance allowed |
| Least material | Ⓛ (LMC) |
| Regardless of size | RFS (default, no bonus) |
| Projected zone | Ⓟ |
Bonus & boundaries (at MMC)
| Bonus tolerance | bonus = |actual − MMC| |
| Total tolerance | total = geo tol + bonus |
| Virtual condition (hole) | VC = MMC − geo tol |
| Virtual condition (shaft) | VC = MMC + geo tol |
Reading a callout
| Feature control frame | | symbol | Ø tol Ⓜ | A | B | C | |
| Datum order | primary → secondary → tertiary (locks 6 DOF) |
| Position preferred | over ± for holes — round zone + bonus |
Formula reference — verify against the governing standard. Not a substitute for engineering judgment.