What does this true position calculator calculate?
Compare signed measured coordinates with a basic position and a diametral tolerance, with optional MMC bonus. Planar coordinate check only. It does not assess axis tilt, datum shift, composite tolerances, projected zones or measurement uncertainty.
Which measurements do you need?
Record basic x coordinate, basic y coordinate, measured x coordinate, measured y coordinate. Check which fields use length, area or a product quantity before entering values.
| Input | Unit / role |
|---|---|
| Basic X coordinate | Measured or specified value |
| Basic Y coordinate | Measured or specified value |
| Measured X coordinate | Measured or specified value |
| Measured Y coordinate | Measured or specified value |
| Specified diametral position tolerance | Measured or specified value |
| Measured feature size | Measured or specified value |
| Feature size at MMC | Measured or specified value |
| Feature size at LMC | Measured or specified value |
Which formula produces the result?
Diametral position = 2√((actual X − basic X)² + (actual Y − basic Y)²); allowed = specified tolerance + valid MMC size departure
Diameter error = 2 × radial offset
How does a worked example look?
Offsets of 0.03 mm in X and 0.04 mm in Y give a radial offset of 0.05 mm and diametral position of 0.10 mm. A 0.12 mm RFS zone leaves 0.02 mm margin.
How should you enter units?
Select metric or imperial before entering dimensions. Switching units converts entered measurement fields; prices and dimensionless percentages keep their values.
Which assumptions affect this estimate?
Planar coordinate check only. It does not assess axis tilt, datum shift, composite tolerances, projected zones or measurement uncertainty.
How should you interpret rounding?
Keep unrounded calculations for comparisons. The result displays practical precision; whole pieces and packages round up where applicable. Display rounding is not a measurement tolerance.
Which project details need another check?
Check the actual product specifications, measurement method and project scope. Planar coordinate check only. It does not assess axis tilt, datum shift, composite tolerances, projected zones or measurement uncertainty.
How can you compare scenarios?
Calculate a baseline, add it to compare, then change one input and calculate again. The comparison keeps input and result snapshots so you can identify what changed.
Which tools can help with the next step?
Use the Machinist & Trade Tools tool directory for related calculations. Keep the scope and units consistent when moving between tools.
