What is interference fit?

Shaft OD larger than hub bore. Assembly requires pressing or thermal expansion. Contact pressure provides grip.

How is contact pressure calculated?

Using Lame thick cylinder theory for same-material fits.

What friction coefficient?

Steel/steel dry: 0.10-0.15. With oil: 0.05-0.08.

Shrink for large sizes or heavy interference. Press for small/medium.

Differential expansion changes interference based on CTE difference.

Free Engineering Tool #076

Press Fit / Interference Fit Calculator

Calculate contact pressure, grip force, and grip torque for interference fits using Lamé equations. Enter shaft and hub dimensions and material properties.

Lamé EquationsGrip TorqueAuto-Calc

Results

Diametral Interference

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Contact Pressure

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Axial Grip Force

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Grip Torque

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Hub Hoop Stress

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Contact Pressure (Lamé)

Grip Force & Torque

Assumes same material for shaft and hub. For different materials, use general Lamé with separate E, ν.

Press Fit / Interference Fit Calculator | Free Tool #076

Published by Nikolai Shelkovenko on February 15, 2026 February 15, 2026

Results

Contact Pressure (Lamé)

Grip Force & Torque