Size shafts, connections and couplings
Assess shaft torque and bending, key shear and bearing stress, interference-fit holding capacity and coupling ratings.
Engineering calculators
Machine Elements Design Calculators
Select and verify machine elements with focused calculations for shafts, interference fits, bearings, threaded joints, springs, gears and power transmission. Start with the design question, then check the loading assumptions, operating conditions and limits of the selected method.
Find your calculation path
Start with the engineering problem
Choose the check or decision you need to make, then open the appropriate calculator.
Verify bearings, springs and bolted joints
Estimate bearing rating life, spring loading and stress, and bolt preload from tightening torque.
Design gearing and roller-chain transmission
Select gear ratios, check simplified spur-gear contact and bending stresses, and assess roller-chain load and geometry.
Calculate power-screw force and self-locking
Estimate lead-screw raising and lowering torque, efficiency, available axial force and friction-dependent backdrive behavior.
Calculator library
All Machine Elements Design Calculators
Browse the complete set of published tools in this engineering category.
Bearing L10 Life Calculator — Basic & ISO 281 Modified Bearing Life
Calculate basic L10 bearing life, modified rating life or the required dynamic load rating from bearing load, speed, bearing type, reliability and an…Bolt Torque & Preload Calculator — Tightening Torque & Proof-Load Target
Estimate bolt preload from tightening torque, calculate required torque from preload, or target a selected percentage of bolt proof load using metric or…Gear Ratio Calculator & Gear Train Solver — Tooth Counts, RPM & Torque
Analyze single-stage, compound and idler spur gear trains, or search 1–3 stage tooth-count combinations for a target ratio or output speed, with ratio…Helical Compression Spring Calculator — Spring Force, Rate & Shear Stress
Helical compression spring design calculator for spring force, deflection, spring rate from geometry, Wahl-corrected shear stress, spring index and solid-height clearance.Lead Screw Torque & Efficiency Calculator — Power Screw Force & Self-Locking
Calculate raising and lowering torque, lead screw efficiency, lifting force from available torque, self-locking and backdrive behavior, travel speed and steady-state power for…Press Fit Calculator — Contact Pressure & Transmitted Torque Validator
Calculate press-fit and interference-fit contact pressure, torque and axial holding capacity across tolerance limits, with hollow-shaft, surface roughness, yield and combined-load checks.Roller Chain Drive Calculator — Chain Pull, Safety Factor & Chain Length
Calculate design chain pull from power, speed, chain pitch and service factor, check manufacturer working-load capacity, and optionally determine sprocket ratio, driven speed,…Shaft Coupling Calculator — Torque Rating, Misalignment & Reaction Loads
Calculate the required coupling torque rating from torque or power and RPM, verify a candidate against nominal, peak and catalog misalignment limits, or…Shaft Diameter Calculator — Torque, Power & Combined Bending
Size solid or hollow shafts from torque or transmitted power, include combined bending with shock/fatigue factors, or check an existing shaft against an…Shaft Key Shear & Bearing Stress Calculator — Required Key Length
Check a rectangular shaft key from torque or power and speed, or size the required effective key length from allowable shear and bearing…Spur Gear Contact & Bending Stress Calculator — Safety Factors & Torque Capacity
Screen a 20° external spur-gear pair using geometry, torque, load factors and material reference stresses to estimate contact stress, Lewis bending stress, safety…Engineering context
Choosing the right level of verification
When a calculator is sufficient
Use an individual calculator when the component, geometry, loads and boundary conditions match its documented model. A focused calculation is useful for early sizing, comparison of design variants and targeted verification of a known failure mode.
- For shafts, establish transmitted torque or power, bending demand and an appropriate allowable stress before sizing.
- For bearings, use representative equivalent loads, rotational speed, reliability level and manufacturer dynamic load ratings.
- For threaded joints and sliding power screws, distinguish clamp force, axial working load, tightening torque and driving torque; these are different engineering models.
- For fits and transmissions, verify the relevant geometry, tolerances, material data and load factors.
When to extend the analysis
Move beyond a standalone calculator whenever the design requires proof of complete component or assembly performance. A passing result for one analytical check does not establish a validated machine design.
- Review combined loading, geometric stress concentrations, fatigue, deflection, buckling and critical speed where applicable.
- Include manufacturing tolerances, assembly conditions, thermal expansion, lubrication, surface finish and wear.
- Use applicable standards and manufacturer data for bearings, fasteners, gear drives and other catalog components.
- Evaluate startup, braking, overloads, transient operating cycles and safety-related functions separately from steady-state calculations.
Common assumptions and mistakes
- Confusing capacity with qualification: calculated torque, preload or life is not automatically an approved design rating.
- Reusing one load case: normal operation, startup, peak load, reversal and fatigue may have different governing conditions.
- Overlooking interfaces: a shaft, key, press fit, bearing and fastener must be checked as a connected assembly, not only as isolated elements.
- Ignoring uncertainty: friction, material properties, tolerances and applied factors can materially change results.
- Assuming self-locking is a safety device: calculated friction-dependent resistance to backdrive does not replace a qualified holding or braking system.
Engineering questions
Frequently asked questions
Which calculator should I start with for a rotating shaft?
Start with the Shaft Diameter Calculator when the objective is first-pass sizing from torque, transmitted power or combined bending and torsion. Then check connections, bearings, deflection, fatigue, critical speed and local stress concentrations as required by the actual assembly.
How do I estimate bearing life?
Use the Bearing L10 Life Calculator with the bearing dynamic load rating, equivalent operating load, speed and bearing type. Reliability and operating-condition factors can be included for adjusted life. Rating life is not a complete assessment of lubrication, contamination, installation or all service-life failure modes.
Is bolt tightening torque the same as power-screw driving torque?
No. Bolt tightening torque is used to generate fastener preload and clamp a joint. Power-screw driving torque is used to convert rotary motion into axial motion or force. The models have different assumptions and should not be substituted for one another.
Can a press-fit calculation prove that a shaft and hub will not slip?
A press-fit calculator estimates interface pressure and frictional torque capacity under selected interference, material and friction assumptions. Final verification should also consider tolerance extremes, thermal effects, surface condition, assembly damage and all imposed loads.
Do simplified gear-stress calculations replace a full gear-rating standard?
No. A simplified contact and tooth-bending calculation can help compare loads, geometry and stress limits. Final design may require the complete applicable rating procedure, detailed load distributions, operating factors, material quality and lifetime checks.
Can one machine-elements calculator validate an entire assembly?
No. Each tool covers a defined calculation model. Mechanical assemblies normally require multiple checks across individual components, interfaces, operating conditions and failure modes, supported by relevant standards and engineering judgement.
Can the roller-chain calculator select a complete chain drive?
It estimates design chain pull and checks an entered manufacturer working-load capacity. Optional geometry outputs cover sprocket ratio, link count, center distance and wrap. Final selection still requires manufacturer ratings, lubrication, wear, alignment and operating-duty checks.
Does the shaft coupling calculator verify every source of misalignment load?
It checks required torque rating and entered coupling limits and can estimate reaction loads from stiffness assumptions. It does not replace the supplier’s complete fatigue, thermal, installation or service-life qualification.