GD&T POSITION CALCULATOR
True Position & GD&T Calculator
Compute position deviation, MMC bonus tolerance, and pass/fail instantly. Enter X/Y deviations, feature size, and tolerance callout — get a clear verdict with the exact percentage of tolerance used. ASME Y14.5 compliant.
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Free Online Tool
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ASME Y14.5 Compliant
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MMC Bonus Included
True Position Calculator
Enter measured deviations and tolerance callout per ASME Y14.5.
True Position
0.0042″
Bonus Tolerance
0.003″
Verdict
✅ PASS
Formula
TP = 2 × √(ΔX² + ΔY²) = 0.0042″ | Total Tol: 0.013″ | 32% Used
ADVANCED GD&T TOOL
Advanced Position Calculator
Compute standard 2D, 3D spherical, or MMC bonus position tolerance for any feature.
True Position
0.0042″
Bonus / Total
+0.003″ / 0.013″
Verdict
✅ PASS
Calculation Summary
TP = 2 × √(0.0015² + 0.0015²) = 0.0042″ | 32% of total tolerance used
HOW IT WORKS
How True Position Is Calculated
Understand the formula, MMC bonus tolerance, and how to read a GD&T position callout per ASME Y14.5.
Standard 2D Formula
TP = 2 × √(ΔX² + ΔY²)
ΔX, ΔY = measured deviations
Multiplier 2 = diametral value
3D Spherical Formula
TP = 2 × √(ΔX² + ΔY² + ΔZ²)
For angled holes, complex ports
Tolerance zone = sphere
Worked Example — True Position Calculation
A hole has basic location X = 2.000″, Y = 1.500″. CMM measures X = 2.0015″, Y = 1.5015″. The callout is ⊕ Ø0.010 Ⓜ with MMC bonus. What's the true position and verdict?
0.0015″ΔX Deviation
²
0.0015″ΔY Deviation
→
0.0042″True Position
≤
0.013″Total Tol (0.010 + 0.003 Bonus)
=
✅ PASS32% of tolerance used
Measured TP
0.0042″
Bonus Earned
+0.003″
Total Tolerance
0.013″
Key GD&T Position Concepts
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True Position Formula
TP = 2 × √(ΔX² + ΔY²). The 2× multiplier converts radial distance to diametral value for direct comparison to the tolerance zone in your feature control frame.
ASME Y14.5-2018 §7.202
MMC Bonus Tolerance
Hole: Bonus = Actual Size − MMC Size. Pin: Bonus = MMC Size − Actual Size. Bonus is earned as the feature departs from MMC, increasing allowable position deviation.
Ⓜ = Maximum Material Condition03
Reading a Callout
⊕ Ø0.010 Ⓜ | A | B | C — position symbol, cylindrical zone, modifier, then primary, secondary, and tertiary datums in order. The ⌀ symbol means diametral (2×) formula applies.
Datum frame = measurement foundationPosition Tolerance Tiers — What's Achievable
⌀0.030″+
Clearance bolt patterns — standard drilling. Cost: $
⌀0.010–0.030″
General location features — CNC milling with rigid fixturing. Cost: $$
⌀0.005–0.010″
Precision assembly — precision boring, in-process probing. Cost: $$$
⌀0.001–0.005″
Dowel pins, bearing seats — 5-axis single-setup, CMM. Cost: $$$$
<⌀0.001″
Gauge tooling, aerospace — jig grinding, climate control. Cost: $$$$$
RFS (No Bonus)
Press-fit dowel pins, bearing seats. No bonus tolerance available.
LMC Bonus
Rare — used when minimum wall thickness is critical. Earn bonus departing from LMC.
CMM INSPECTION & COST
True Position — From CMM to Cost
How position tolerances are inspected, what each tier costs to manufacture, and where you can save.
CMM Workflow
1. Establish datum frame (A→B→C) · 2. Measure feature axis · 3. Compute deviations · 4. Apply bonus · 5. Pass/Fail verdict.
- Datum order matters — wrong order = wrong results
- % Used = (TP ÷ Total Tol) × 100
- Under 80% = process in control
Cost Impact
⌀0.030″ = baseline · ⌀0.010″ adds 30–50% · ⌀0.005″ adds 100–200% · ⌀0.001″ adds 300–500%.
- 5-axis single-setup = best for tight tolerances
- CMM inspection adds cost — but catches non-conforming parts
- Relax non-critical features to save 60%+
Savings Strategies
Reserve tight position tolerances for features that actually need them — dowel pins, bearing bores, alignment features.
- Bolt holes: ⌀0.030″ is fine
- Dowel holes: ⌀0.005″ as needed
- Same function, 64% cheaper
Need parts inspected and verified?
Baetro holds true position tolerances to 0.001″ with full CMM inspection reports on every order. Upload your CAD and drawing — get an instant quote and free DFM review.
GD&T Position FAQs
Frequently Asked Questions
True position defines a cylindrical tolerance zone centered on the theoretically exact location of a feature. The feature's actual center must fall within that cylinder. Specified using the ⊕ symbol in a feature control frame per ASME Y14.5.
TP = 2 × √(ΔX² + ΔY²). The multiplier of 2 converts radial distance to a diametral value for comparison to the cylindrical tolerance zone. For 3D: TP = 2 × √(ΔX² + ΔY² + ΔZ²).
When the Ⓜ modifier is used, bonus tolerance is earned as the feature departs from MMC. For a hole: Bonus = Actual Size − MMC Size. For a pin: Bonus = MMC Size − Actual Size. A Ø0.500″ ±0.005″ hole with ⊕ Ø0.010 Ⓜ earns up to 0.010″ bonus.
True position controls feature location using a cylindrical zone. Concentricity controlled median point alignment to a datum axis — it was removed from ASME Y14.5-2018. Use position tolerance for coaxial features — easier to inspect and more functional.
Use MMC for clearance bolt holes and fastener patterns — extra deviation won't harm assembly. Use RFS for press-fit dowel pins, bearing seats, and precision locating features where position must be maintained regardless of feature size.
Standard CNC: ⌀0.005–0.010″. Precision 5-axis single-setup: ⌀0.001–0.005″. Under ⌀0.001″ requires jig grinding or honing. Baetro holds true position to 0.001″ with full CMM inspection on every order.
Cost increases sharply: ⌀0.030″ is baseline. ⌀0.010″ adds 30–50%. ⌀0.005″ adds 100–200%. ⌀0.001″ adds 300–500%. Only apply tight position tolerances to features that need them — dowel pins, bearing bores — and let everything else run at ⌀0.030″ or looser.
PRECISION MANUFACTURING SUPPORT
From GD&T Callout to Machined Part
You've verified the tolerance. Now get parts machined to those numbers. Baetro holds true position tolerances to 0.001″ with full CMM inspection reports on every order. 5-axis single-setup machining eliminates datum shift — ISO 9001 / AS9100 certified, parts ship in 3–7 days. Upload your CAD and drawing for an instant quote.
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Precision CNC machining
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Full CMM inspection reports
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Free DFM review & feedback