Hole Clearance Fit Class Calculator
Free Hole clearance fit class Calculator for materials specifications projects. Enter dimensions to get material lists and cost estimates.
Formula
Clearance = Hole Size - Shaft Size
For each fit class, the hole and shaft have specified tolerance bands relative to the nominal size. The minimum clearance equals the minimum hole diameter minus the maximum shaft diameter. The maximum clearance equals the maximum hole diameter minus the minimum shaft diameter. Fit class determines the tolerance factors applied.
Frequently Asked Questions
What are the ANSI running and sliding fit classes?
ANSI defines eight classes of running and sliding clearance fits (RC1 through RC8). RC1 provides the tightest fit with minimal clearance for precision location. RC2-RC3 are sliding fits for accurate location with greater freedom. RC4-RC5 are close to medium running fits for journal bearings. RC6-RC7 are medium to free running fits where wide clearance is needed. RC8 is a loose running fit used where accuracy is not critical.
How do I determine which fit class to use?
The choice depends on the functional requirement of the assembly. For precision instruments and location fits, use RC1 or RC2. For bearings with light loads and moderate speeds, RC3 or RC4 are appropriate. For general-purpose bearings under normal conditions, RC5 or RC6 work well. For heavy-duty or high-temperature applications where thermal expansion is a concern, choose RC7 or RC8 for generous clearance.
What is the difference between clearance, transition, and interference fits?
In a clearance fit, the shaft is always smaller than the hole, allowing free movement between parts. In a transition fit, the shaft may be slightly larger or smaller than the hole depending on where the actual sizes fall within tolerance. In an interference fit (press fit), the shaft is always larger than the hole, requiring force or heat to assemble. Hole Clearance Fit Class Calculator focuses on clearance (running/sliding) fits only.
Why is tolerance important in hole and shaft fits?
Tolerance defines the permissible variation in manufactured dimensions. Without proper tolerances, the clearance between mating parts could be too tight (causing seizure or excessive wear) or too loose (causing vibration and poor performance). The tolerance band determines the range of acceptable clearances. Tighter tolerances require more precise and expensive machining, so engineers balance functional requirements against manufacturing cost.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
Can I use Hole Clearance Fit Class Calculator on a mobile device?
Yes. All calculators on NovaCalculator are fully responsive and work on smartphones, tablets, and desktops. The layout adapts automatically to your screen size.