GD&T True Position

Diametral position from measured X and Y deviations, with bonus tolerance at MMC.

Measured deviation

ΔX from true positionsign doesn't matter ΔY from true position Stated position tol (Ø)from the feature control frame

Bonus tolerance (MMC modifier)

Modifier

Results

Diametral true position is 2×√(ΔX² + ΔY²) — twice the radial miss, so it compares directly to the Ø tolerance in the frame. With the Ⓜ modifier, every bit the feature departs from MMC gets added to the position budget. Radial numbers double to diametral.