12 reference tools
Shaft Calculators: Stress, Deflection & Critical Speed
Calculate shaft torsion, diameter, bending stress, bearing reactions, deflection, critical speed, key stress, and rigid flange coupling loads.
How do you choose a shaft calculation?
Choose reactions and bending moment when the transverse loads are known, deflection when stiffness matters, and torsion or combined stress when torque is involved. Use the critical-speed tools only after selecting the appropriate deflection or rotor model. Key and rigid-coupling checks address separate connections. These are individual reference calculations with stated assumptions, rather than a complete fatigue or rotor-dynamics assessment.
Choose a calculator
- #020
Shaft Torsional Stress / Angle of Twist Calculator
Calculate torsional shear stress, angle of twist, polar moment, and stiffness for a solid or hollow circular shaft under elastic torsion.
- #021
Shaft Diameter Calculator — Torsional Stress / Twist
Size a solid or hollow shaft from torque, allowable nominal shear stress, and twist limits. Compare stress-controlled and stiffness-controlled diameters.
- #022
Shaft Combined Bending and Torsion Calculator
Calculate nominal shaft bending and torsional stress, principal stresses, and von Mises and Tresca equivalent stress from moments and shaft geometry.
- #023
Shaft Bearing Reactions / Bending Moment Calculator
Calculate two-support shaft bearing reactions, shear forces, and maximum bending moment from one or two transverse point loads.
- #024
Simply Supported Shaft Deflection / Slope Calculator
Calculate elastic deflection, maximum-deflection location, and support slopes for a simply supported circular shaft with up to two point loads.
- #025
Shaft Critical Speed / Whirling Calculator
Estimate single-rotor shaft critical speed from gravity static deflection and compare operating RPM with a user-selected review band.
- #026
Rayleigh Multi-Mass Shaft Critical Speed Calculator
Estimate shaft critical speed with Rayleigh’s method using up to four rotating weights and their station-specific total gravity deflections.
- #027
Dunkerley Multi-Mass Shaft Critical Speed Calculator
Estimate shaft critical speed with Dunkerley’s equation from up to four isolated single-mass gravity deflections. Review the model assumptions.
- #028
Shaft Key Shear / Bearing Stress Calculator
Calculate rectangular shaft-key shear and bearing stress, utilization, and required effective length using supplied allowable stresses.
- #029
Rigid Flange Coupling Bolt Shear Calculator
Calculate fitted-bolt shear stress, torque capacity, and required diameter for an ideal equal-radius rigid flange coupling.
- #030
Flange Coupling Bolt Bearing and Edge Shear-Out Calculator
Check nominal flange-hole bearing and edge shear-out, governing utilization, torque capacity, and required coupling flange thickness.
- #031
Flange Coupling Bolt Preload and Slip Resistance Calculator
Calculate ideal flange-coupling slip torque and required bolt preload from retained clamp force, friction coefficient, and annular contact geometry.
Before you use the result
- Establish support positions, load stations, shaft geometry, and material properties before calculating reactions, stress, or deflection.
- Keep nominal shaft stress separate from keyway stress concentration, fatigue, and allowable-stress decisions. Enter an allowable only when its basis is known.
- For critical-speed handoffs, check whether the destination needs a station-specific deflection, a single-rotor deflection, or isolated single-mass cases. These inputs are not interchangeable.
Each linked tool includes its own formulas, worked examples, input units, limitations, and source notes. See how MechClarity documents and checks its calculations.
Continue with related calculations
- Bearing Calculators: L10 Life, Loads & Static Safety — Calculate bearing L10 life, equivalent dynamic and static loads, required dynamic rating, static safety factor, and variable-duty equivalent load.
- Power, Torque & RPM Calculator and Drive Tools — Convert between shaft power, torque, and rotational speed in SI or imperial units, then continue to gear, pulley, shaft, and bearing calculations.
- Bolt Calculators: Torque, Preload & Joint Stiffness — Estimate bolt torque and preload, bolt and clamped-member stiffness, external load sharing, joint separation, and thermal preload change.