Drivetrain & Shop Tool Calculators

Gear ratio, torque wrench correction, precision conversion, threading, and shop reference tools.

Calculators in this category

• Gear Ratio & Final Drive Calculator — Calculate RPM at speed for any axle ratio, tire size, and transmission. Compare gear ratios side by side.
• Torque Wrench Extension Calculator — Corrected torque wrench setting for crow's foot adapters, offset extensions, and wobble sockets.
• MM to Inch Converter — High-precision metric to imperial conversion for engine builders. Includes machinist reference tables and fractional inch equivalents.
• Wrench Size Converter — SAE to Metric + Measure with Calipers — Convert SAE wrench sizes to metric and back, or measure the bolt head with calipers / tape and get the right wrench from either set. Exact gap and torque-safe interchange tiers.
• Density Altitude / HP Correction Calculator — Calculate density altitude, relative HP, and dyno correction factors for SAE J1349, J607, and DIN 70020. Dew point or RH input.
• Torque Converter Stall Speed Calculator — Find the right converter stall speed for your build. Recommended stall range, converter diameter, launch analysis, and cruise RPM.
• Decimal to Fraction Inch Converter — Full 1/64" Chart + Tap Drill & Wrench Sizes — Free decimal ↔ fraction inch converter with full 1/64" reference chart (0 to 1"), tap drill decimal equivalents (75% thread), SAE wrench sizes with metric equivalents, engine-builder thousandths reference (bearing clearance, ring gap, quench), and 12-question FAQ.
• Tap Drill Size Lookup — Pick a tap, get the drill. Imperial UNC/UNF and metric coarse/fine with 75% and 50% thread engagement sizes for any common tap.
• Thread Pitch Converter — TPI to Metric — Identify a thread when you have only TPI or only metric pitch. TPI × pitch (mm) = 25.4. Common UNC/UNF and metric pitches in quick reference.
• Torque Units Converter (ft-lb / Nm / in-lb) — Convert between ft-lb, Nm, in-lb, and kgf·m. Common engine torque references included for spec lookup.
• Temperature Converter (°F / °C / K) — Fahrenheit, Celsius, and Kelvin with engine reference points: coolant, oil, EGT zones (cold / normal / hot / danger).

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