GD&T True Position Calculator (MMC, LMC, RFS)
Instantly check position tolerance, bonus tolerance, and pass/fail
Advertisement
True Position Calculator (MMC, LMC, RFS) – GD&T Position Tolerance Tool
This true position calculator helps you calculate position tolerance, bonus tolerance, and pass/fail results based on GD&T standards. It supports MMC (Maximum Material Condition), LMC, and RFS, making it useful for machinists, inspectors, and engineers.
True position defines how far a feature, such as a hole or pin, can deviate from its exact theoretical location. Instead of separate X and Y tolerances, GD&T combines them into a single diametrical tolerance zone.
When MMC is applied, bonus tolerance is gained as the feature departs from its maximum material condition. This allows additional positional variation while still maintaining proper assembly fit.
What This GD&T True Position Calculator Does
This GD&T True Position Calculator helps you quickly determine whether a feature is within tolerance.
It automatically calculates:
• Radial deviation from the nominal position
• True position (diametrical value)
• Bonus tolerance for MMC and LMC conditions
• Total allowed tolerance
• Pass or fail result
This tool is designed for machinists, inspectors, and engineers who need fast, accurate answers without manual calculations.
How to Use This Tool
Enter the nominal basic position from the drawing
Enter the actual measured position
Input the position tolerance
Select feature type: hole or pin
Select material condition: MMC, LMC, or RFS
Enter feature size if applicable
Click Calculate
The results will instantly show true position, bonus tolerance, and pass/fail status.
Understanding Bonus Tolerance (MMC / LMC / RFS)
Bonus tolerance is additional tolerance gained when a feature departs from its maximum material condition.
• For holes: larger hole size = more bonus tolerance
• For pins: smaller pin size = more bonus tolerance
• MMC (Maximum Material Condition): Bonus increases as material is removed
• LMC (Least Material Condition): Bonus increases as material is added
• RFS (Regardless of Feature Size): No bonus tolerance is applied
This calculator automatically applies the correct bonus tolerance based on your inputs.
True Position Formula
Radial deviation = √((X actual − X nominal)² + (Y actual − Y nominal)²)
True position = 2 × radial deviation
Bonus tolerance for holes = Actual size − MMC
Bonus tolerance for pins = MMC − Actual size
Total tolerance = Position tolerance + Bonus tolerance
Example (MMC Condition)
Basic position: (2.000, 1.500)
Actual position: (2.006, 1.496)
Position tolerance: Ø0.010
Hole size at MMC: Ø10.000
Actual hole size: Ø10.006
Result:
True Position = Ø0.0144
Bonus = Ø0.0060
Total Allowed = Ø0.0160
Status = PASS
Related Machining Calculators
Use these related machining calculators to improve accuracy and save time:
Advertisement
Contact
Questions? Contact us:
support@machiningcalculators.com
© 2026. All rights reserved.
Built for Machinists. Designed for the Shop Floor.
Professional CNC calculators, GD&T tools, and machining utilities for real-world manufacturing applications.