Bolt Torque Spec Calc

About this app

Built for mechanics, millwrights, and equipment installers who need bolt torque on the bench - not a desktop tool. WHAT IT DOES Looks up torque values for standard bolt sizes and grades using the T = K x D x F formula with K = 0.20. SAE grades 2, 5, and 8 across 28 sizes from #6-32 to 1-1/2 inch. Metric classes 4.6, 8.8, 10.9, and 12.9 across 17 sizes from M3 to M36. Dry vs. lubricated multiplier applied to the result. INPUTS - Standard: SAE or Metric - Bolt size (28 SAE or 17 metric sizes available) - Bolt grade or class - Lube condition: Dry or Lubricated RETURNS - Torque in ft-lb - Torque in N·m CALCULATION BASIS - Torque formula: T = 0.20 x D x F - Preload F = 75% of proof strength times tensile stress area - Lubricated multiplier: 0.75 times the dry value WHY THIS APP, NOT THE FREE ONES - Math is shown - formula and assumed K factor visible, not hidden. - 45 size and grade combinations covered in one tap. - Works offline - shop floor, field repair, no Wi-Fi. Always available. - No login. No ads. No telemetry. No subscription. PRICING $1.99. Pay once, own it. Lifetime access on iPhone, iPad, and Mac via Family Sharing. NOT A SUBSTITUTE FOR Manufacturer-specified torque values for safety-critical fasteners. Calibrated wrench certificates. Specific K-factor adjustments for anti-seize, plating, or galvanized threads - this app uses K = 0.20 for both dry and lubricated, with the 0.75x multiplier as the only lube adjustment. Verify against the OEM tightening spec for the specific application.

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Momentum comes from crawler snapshots for the tracked storefront. “Viral growth signal” means unusually fast recent rating gains; it is an indicator, not download data.

1. First observed Oct 2, 2026 · 7:51 PM $4.99