Tolerance & Fit Calculator - ISO 286 Shaft & Hole Fits with Visual Tolerance Zones

How It Works

1. Enter Nominal Size

   Input the nominal basic dimension in millimeters. The app screens supported sizes over 0 through 500 mm and displays inch equivalents only as converted output.

2. Select Hole Tolerance

   Choose a supported hole designation. The app calculates local deviation prompts and shows the ISO source warnings that still require licensed-table verification for critical work.

3. Select Shaft Tolerance

   Choose a supported shaft designation. Letters a-h generally sit below nominal, while higher letters move into transition or interference ranges; final interpretation still needs drawing and inspection review.

4. Use Presets (Optional)

   Select a common preset such as H7/g6, H7/h6, H7/k6, H7/p6, or H7/s6 as a starting point. The preset only fills the designations and does not approve the fit.

5. Review Results

   See the upper and lower limits for both hole and shaft, maximum and minimum clearance or interference, fit type classification, tolerance-zone diagram, and source warnings.

Built For

• Engineering and machining teams screening supported ISO-style hole and shaft designations before drawing review
• Machinists estimating local size limits before checking the current drawing, process plan, and gauges
• Toolmakers comparing tolerance-zone relationships for guide pins, dowels, and bushings before specification review
• Maintenance technicians checking whether measured parts appear near a requested tolerance zone before inspection escalation
• Students and apprentices learning the relationship between deviation, IT grade, and fit type
• Quality teams preparing questions for calibrated inspection against current drawings and authorized standards

Features & Capabilities

ISO 286 Deviation Tables

Fundamental deviation rows for the commonly used hole positions A through U and shaft positions a through u, with IT grades 01 through 16 computed from the ISO 286-1 tolerance-factor formula. Above 50 mm the r/s/t/u rows use the larger (conservative) sub-band value per dimension range, and hole R-U rows omit the ISO Delta adjustment; the in-app source boundary documents these approximations. Verify critical fits against the licensed ISO 286-1/286-2 tables.

Visual Tolerance Zone Diagram

An interactive diagram shows the hole and shaft tolerance zones as colored bands relative to the nominal dimension. Clearance appears as a gap between bands, interference as an overlap. The diagram updates in real time as you change selections.

Common Fit Presets

Built-in preset prompts include H11/c11 (loose running), H9/d9 (free running), H8/f7 (close running), H7/g6 (sliding), H7/h6 (locational clearance), H7/k6 (locational transition), H7/n6 (locational interference), H7/p6 (press), and H7/s6 (heavy press). Each label is context only and does not approve an application.

Max/Min Clearance and Interference

Calculates the maximum clearance, minimum clearance, maximum interference, and minimum interference for the selected fit. For transition fits where the result can be either clearance or interference, both worst-case values are shown with an explicit caution.

Fit Type Classification

Classifies the calculated limit relationship as clearance, transition, or interference. Treat the category labels as context prompts, not application approval.

Inch/Metric Support

Primary calculations are in metric per ISO 286. The nominal size is entered in millimeters, and results can be displayed in either millimeters or inches for shops that work in imperial.

Assumptions

• Local deviation rows and IT-grade arithmetic are based on ISO 286 concepts, with source gaps disclosed in-app
• Hole-basis presets are prompts only; user-selected designations control the calculation
• Nominal-size calculations are interpreted at standard dimensional-inspection conditions; temperature effects are not modeled
• Maximum and minimum clearance/interference calculated from worst-case combinations of hole and shaft limits
• Fit type classification (clearance, transition, interference) determined by overlap of tolerance zones
• Supported UI options are a bounded subset and do not reproduce every ISO 286 designation or table condition

Limitations

• Does not account for thermal expansion that changes effective fit at operating temperatures above or below 20 degrees C
• Surface finish effects on functional fit not modeled; rough surfaces reduce effective clearance
• Does not calculate press fit assembly force, extraction force, or holding torque for interference fits
• Elastic deformation of thin-walled parts under interference fit not considered in the tolerance zone model
• Geometric tolerances (roundness, cylindricity, straightness) that affect real fit behavior are not included
• Plating and coating thickness changes effective dimensions and must be accounted for separately

References

• ISO 286-1:2010 - Geometrical Product Specifications (GPS) - ISO Code System for Tolerances on Linear Sizes
• ISO 286-2:2010 - Tables of Standard Tolerance Classes and Limit Deviations for Holes and Shafts
• ASME B4.1 - Preferred Limits and Fits for Cylindrical Parts (inch-based RC, LC, LT, LN, FN fits)
• Machinery's Handbook, 31st Edition - Tolerance, Allowance, and Preferred Fits Tables
• ISO 1 - Geometrical Product Specifications - Standard Reference Temperature for Product Specification

Frequently Asked Questions