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Press Fit Calculator | Interference Fit Stress & Force
Calculate interface pressure, assembly force, and hoop stress for your interference fit.
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Interference & Clearance Fit Calculator
Calculate hole and shaft tolerance ranges, clearance or interference limits, and fit class descriptions for shaft-hole assemblies per ISO 286. Select a fit class and nominal diameter to see results in real time.
Quick Answer: How Do I Pick a Clearance or Interference Fit?
A fit is the dimensional relationship between a shaft and a hole, set by their tolerance zones. A clearance fit always leaves a gap so parts move freely, an interference fit overlaps so parts must be pressed together and a transition fit can land either way. Fits are specified per ISO 286 using hole-basis callouts like H7/g6, where the letter sets the tolerance zone and the number sets the grade.
This calculator takes a nominal diameter and an ISO 286 fit class and returns the hole tolerance limits, the shaft tolerance limits and the resulting clearance or interference range, in metric or imperial units. Inputs include the nominal size and a hole/shaft fit class such as H7/g6, H7/h6 or H7/p6.
Common fits at 25 mm nominal: H7 hole tolerance 0–+0.021 mm | H7/g6 sliding clearance 0.007–0.041 mm | H7/h6 close sliding 0–0.034 mm | H7/p6 light press fit (interference) | clearance, transition and interference all selectable.
Fit Parameters
Common Fit Classes Reference
| Fit Class | Type | Typical Use |
|---|---|---|
| H11/c11 | Clearance | Extra loose, dirty environments |
| H9/d9 | Clearance | Loose running, large bearings |
| H8/f7 | Clearance | Free running, journal bearings |
| H7/f6 | Clearance | Easy running, small bearings |
| H7/g6 | Clearance | Sliding fit, precision bearings |
| H7/h6 | Clearance | Close sliding, spigot fits |
| H7/js6 | Transition | Location, centered tolerance |
| H7/k6 | Transition | Location, slight interference likely |
| H7/n6 | Transition | Location, tighter |
| H7/p6 | Interference | Light press fit, dowel pins |
| H7/r6 | Interference | Medium press fit |
| H7/s6 | Interference | Heavy press fit, permanent |
Results
Clearance Fit
Visual Boundary Scale
Outer: Hole | Inner: Shaft
Fit Class
H7/g6
Hole Tolerance (H7)
Hole Min
25.000 mm
Hole Max
25.021 mm
Shaft Tolerance (g6)
Shaft Min
24.980 mm
Shaft Max
24.993 mm
Clearance Range
Min Clearance
0.007 mm
Max Clearance
0.041 mm
H7/g6 — Sliding Fit:
A precision sliding fit for bearings and guides. The shaft slides freely in the hole with minimal play. Ideal for parts that need accurate alignment with easy assembly and disassembly.
A precision sliding fit for bearings and guides. The shaft slides freely in the hole with minimal play. Ideal for parts that need accurate alignment with easy assembly and disassembly.
Based on ISO 286-1 standard tolerance grades. Verify critical fits with your drawing specifications.
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Upload CAD for Instant QuoteFrequently Asked Questions
A clearance fit always has a gap between the shaft and hole, allowing free movement. An interference fit (press fit) always has overlap, requiring force to assemble. A transition fit can result in either a slight clearance or slight interference, depending on where each part falls within its tolerance range. Use clearance fits for rotating parts, interference fits for permanent joints, and transition fits for accurate location.
H7/g6 is a fit designation per ISO 286. The letter indicates the fundamental deviation (position of the tolerance zone relative to nominal). The number indicates the IT grade (width of the tolerance zone). H7 means the hole has a fundamental deviation of zero (starts at nominal) with IT grade 7. g6 means the shaft is slightly below nominal with IT grade 6. Together, H7/g6 creates a sliding clearance fit.
H7/h6 is the most commonly specified fit. It gives a close sliding fit with minimal clearance. H7/g6 is popular for bearings and sliding fits. H7/p6 and H7/s6 are common interference fits for press-fit pins and dowels. The right fit depends on whether the parts need to slide, locate precisely, or be permanently joined.
ISO 286 is the international standard for limits and fits using the hole-basis or shaft-basis system with letter-number designations like H7/g6. ANSI B4.1 is the American standard that uses RC, LC, LT, LN, and FN class designations. Both systems achieve the same goal but use different notation. ISO 286 is more widely used globally.
Hole-basis fits (capital H for the hole) are the most common because it is easier and cheaper to adjust shaft size than to ream or bore a hole to a specific size. Use shaft-basis fits when you have a standard shaft size (like ground rod stock) and want to adjust the hole. Most engineering drawings and this calculator use the hole-basis system.
Fits & Tolerances Reference Series
Related references — jump to the one you need:
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