Comparison Mode — Side-by-Side Engineering Design Screening Calculator

None — and that is deliberate. Comparison Mode is a screening tool: every panel is a simplification of the dedicated calculator and is marked with an "Engineering estimate" badge naming the tool that governs. Two pieces are exact: the bearing equivalent dynamic load is the same ISO 281 interpolation the Bearings engine uses, and the bolt tensile stress area is the ISO 898-1 definition. Everything else deliberately omits factors the full standard requires — the gear panel applies no ISO 6336 load factors, the shaft panel assumes a single diameter with fully reversed bending, the beam panel assumes a symmetric section and a midspan or tip load. Use the dedicated per-tool calculator for any design you will sign.

Yes — the Comparison Mode is fully free with no sign-up required. You can also use every other MechanixCalc tool during a free 30-minute preview with no account, and a 14-day account trial (no credit card) unlocks the full suite. Saving calculations to your account and generating branded PDF engineering reports are available on a paid plan.

Six: deep-groove ball bearings (ISO 281 L10 life), solid circular shafts (bending, torsion, screening DE-Goodman fatigue), SPUR gear pairs (pitch-point contact stress, root bending stress, gear ratio — no helix angle or profile shift), beams (simply-supported or cantilever, point load + UDL), helical compression springs (stiffness, deflection, shear stress), and metric bolted joints (preload, clamp force, stress area, VDI 2230 reduced-stress safety factor).

For each output metric the tool computes Δ = (B − A) / |A| × 100 %, and a positive Δ means Design B is higher than A. A winner is marked only on metrics that HAVE a better: higher is better for the safety factors and for bearing life; lower is better for stresses, deflections, and the loads and moments that drive them. Metrics that are design targets rather than objectives — gear ratio, the two pitch diameters, spring rate, spring index, spring deflection, bolt stress area, preload per bolt and total clamp force — show the delta with no winner, because neither direction is an improvement on its own. On the shaft panel, read the "SF Governing" row rather than either safety factor alone: the yield check deliberately carries no notch factor, so it reads higher than the fatigue check. If either design falls outside its screening model — a cleared field, a negative value, or a magnitude the model cannot represent — that column is refused and the comparison is withheld entirely rather than ranked.

Use Comparison Mode for rapid early-stage trade studies — comparing two bearing sizes, two shaft diameters, or two spring wire gauges — where you need a quick delta before committing time to a full standards-cited calculation. For a final design sign-off, use the dedicated per-tool calculator: it applies the complete standard method, stress-concentration factor libraries, material databases and generates a reviewable PDF report with the governing standard cited on every output.