Press Fit and Shrink Fit Calculator

Formula

• Contact pressure P from thick-cylinder interference fit
• Hub hoop stress = P × (Do² + D²) / (Do² − D²)
• Torque capacity = μ × P × π × D² × L / 2
• Axial force capacity = μ × P × π × D × L

About this calculator

Part of our Mechanical Calculators collection. Beams, bolts, springs, gears, bearings, and core ME calculations.

How it works

Contact pressure comes from thick-cylinder interference fit theory using interference, diameters, and elastic moduli. Torque and axial capacity use contact pressure times friction on the joint diameter. Check hoop stress limits before selecting interference.

Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.

Worked example

50 µm interference on 40 mm shaft, 80 mm hub OD, E = 200 GPa, ν = 0.3, μ = 0.15.

1. Compliance from shaft and hub elastic terms
2. Contact pressure ≈ 93.8 MPa
3. Hub hoop stress ≈ 156 MPa
4. Torque capacity ≈ 2827 N·m

Result: Contact pressure 93.8 MPa, torque capacity 2827 N·m.

When to use

• Checking hoop stress limits on a hub before press fit
• Estimating torque transmission capacity of an interference joint
• Sizing interference for shaft–hub assemblies

Limitations

• Contact length L assumed as 2× nominal diameter
• Solid shaft (Di = 0) or hollow shaft via inner diameter input
• Does not include thermal shrink-fit temperature change

FAQ

How is interference entered?

Enter radial interference in micrometres (µm) — the diametral oversize of the shaft relative to the hub bore.

What friction coefficient for torque?

Dry steel-on-steel is often 0.10 to 0.20. Use measured or catalog values for your surface finish and lubrication state.