Technical Information
Gage Tolerance
Understanding the Gage Tolerance 10% Rule
The Gage Tolerance 10% Rule is designed to guide the selection of the appropriate tolerance for Go/NoGo gages. This rule suggests that if you allocate 10% of the total product tolerance to the gages, you can confidently inspect 90% of your product tolerance 100% of the time.
Go/NoGo Gages
- For Plug Gages, the “Go” typically has a plus tolerance and the “NoGo” a minus tolerance.
- For Ring Gages, the situation is reversed: the “Go” typically has a minus tolerance and the “NoGo” a plus tolerance.
By following the 10% rule, gage tolerance is integrated into part tolerance, allowing up to a 10% variance. This means the selected gage can effectively detect the variation present, ensuring that no defective product passes inspection. However, it’s important to note that up to 10% of good products may potentially fail the inspection, but no bad products will pass.
For a simplified application of this rule, select a gage that is 10x more accurate than the characteristic you intend to measure.
Tolerance Chart
Tolerance Chart (Inch)
| Diameters (Inch) Above-Including | Tolerance Class | |||||
| XXX | XX | X | Y | Z | ZZ | |
| 0.010” to 0.825” | 0.000010” | 0.000020” | 0.000040” | 0.000070” | 0.0001” | 0.0002” |
| 0.825”to 1.510” | 0.000015” | 0.000030” | 0.000060” | 0.000090” | 0.00012” | 0.00024” |
| 1.510” to 2.510” | 0.000020” | 0.000040” | 0.000080” | 0.00012” | 0.00016” | 0.00032” |
| 2.510” to 4.510” | 0.000025” | 0.000050” | 0.0001” | 0.00015” | 0.0002” | 0.0004” |
| 4.510” to 6.510” | 0.000033” | 0.000065” | 0.00013” | 0.00019” | 0.00025” | 0.0005” |
| 6.510” to 9.010” | 0.000040” | 0.000080” | 0.00016” | 0.00024” | 0.00032” | 0.00064” |
| 9.010” to 12.010” | 0.000050” | 0.0001” | 0.0002” | 0.0003” | 0.0004” | 0.0008” |
Tolerance Chart (Metric)
| Diameters (Metric) Above-Including | Tolerance Class | |||||
| Pin and Plug Gages | XXX | XX | X | Y | Z | ZZ |
| .254mm to 20.96mm | .00025mm | .00051mm | .00102mm | .00178mm | .00254mm | .00508mm |
| 20.96mm to 38.35mm | .00038mm | .00076mm | .00152mm | .00229mm | .00305mm | .00610mm |
| 38.35mm to 63.75mm | .00051mm | .00102mm | .00203mm | .00305mm | .00406mm | .00813mm |
| 63.75mm to 114.55mm | .00064mm | .00127mm | .00254mm | .00381mm | .00508mm | .01016mm |
| 114.55mm to 165.35mm | .00084mm | .00165mm | .00330mm | .00483mm | .00635mm | .01270mm |
| 165.35mm to 228.85mm | .00102mm | .00203mm | .00406mm | .00610mm | .00813mm | .01626mm |
| 228.85mm to 305.05mm | .00127mm | .00254mm | .00508mm | .00762mm | .01016mm | .02032mm |
Plus tolerance gage is used to gage the low limit. Minus tolerance is used to gage the upper limit.
Tolerance Direction
| Gage Type | Direction | |
| GO | NO-GO | |
| OD Cylindricals (Plugs) | Plus | Minus |
| ID Cylindricals (Rings) | Minus | Plus |
Plus tolerance gage is used to gage the low limit. Minus tolerance is used to gage the upper limit.
Gage Calculator
*Parameters and results are rounded to 8 decimal places.
*Suggested gage tolerance is calculated using the 10% product tolerance rule.