Complete ISO tolerance and fit standards chart with clearance, transition, and interference fits. Essential reference for precision CNC machining and mechanical engineering applications.
The ISO tolerance system provides standardized methods for specifying dimensional tolerances and fits between mating parts. This system ensures interchangeability and proper function of mechanical assemblies across different manufacturers and applications.
Fits are classified into three main categories: clearance fits (always have clearance), interference fits (always have interference), and transition fits (may have either clearance or interference depending on actual manufactured dimensions).
| Fit | Type | Description | Min Clearance (mm) | Max Clearance (mm) | Application |
|---|---|---|---|---|---|
| H11/c11 | Clearance | Loose running fit | +0.06 | +0.18 | Large temperature variations, high running speeds |
| H9/d9 | Clearance | Free running fit | +0.025 | +0.075 | General machinery, pumps, textile machinery |
| H8/f7 | Clearance | Close running fit | +0.01 | +0.04 | Precision machinery, automotive applications |
| H7/g6 | Clearance | Sliding fit | +0.005 | +0.02 | Accurate location, easy assembly |
| H7/h6 | Clearance | Locational clearance | 0 | +0.015 | Snug fit for location only |
| H7/js6 | Transition | Locational transition | -0.008 | +0.008 | Accurate location, light assembly forces |
| H7/k6 | Transition | Locational transition | -0.012 | +0.003 | More accurate location than js6 |
| H7/m6 | Transition | Locational transition | -0.02 | -0.005 | Accurate location, some interference |
| H7/n6 | Transition | Locational interference | -0.025 | -0.01 | Light drive fit, hand assembly |
| H7/p6 | Interference | Light drive fit | -0.035 | -0.02 | Light assembly forces, permanent assembly |
| H7/s6 | Interference | Medium drive fit | -0.05 | -0.035 | Ordinary steel parts, cast iron hubs |
| H7/t6 | Interference | Tight drive fit | -0.065 | -0.05 | Heavy steel parts, shrink fits |
| H7/u6 | Interference | Force fit | -0.08 | -0.065 | Parts requiring high stress, permanent assembly |
| H6/s5 | Interference | Press fit | -0.04 | -0.025 | Precision press fits, bearing races |
| Grade | Tolerance (mm) | Typical Application |
|---|---|---|
| IT01 | ±0.0003 | Ultra precision gauge blocks |
| IT0 | ±0.0005 | Precision gauge blocks |
| IT1 | ±0.0008 | Very high precision measuring tools |
| IT2 | ±0.0012 | High precision measuring tools |
| IT3 | ±0.0018 | High precision work, gauges |
| IT4 | ±0.0027 | High precision work, broaching |
| IT5 | ±0.004 | High precision work, grinding, honing |
| IT6 | ±0.006 | Medium precision work, turning, boring |
| IT7 | ±0.01 | Medium precision work, turning, boring |
| IT8 | ±0.014 | General precision work, milling |
| IT9 | ±0.025 | General precision work, drilling |
| IT10 | ±0.04 | General work, rough turning |
| IT11 | ±0.06 | Rough work, rough turning |
| IT12 | ±0.1 | Very rough work, stamping |
Always provide clearance between mating parts. Used where parts must move relative to each other.
May result in either clearance or interference depending on actual part dimensions.
Always provide interference between mating parts. Used for permanent assemblies.
Most common system where the hole tolerance is fixed and shaft tolerance varies.
Alternative system where shaft tolerance is fixed and hole tolerance varies.
Our CNC machining services deliver precise tolerances and fits according to ISO standards for critical applications.