Gear ratio, torque wrench correction, precision conversion, thread and tap drill sizing, and shop reference tools, with the charts on the page.
Calculators in this category
Gear Ratio & Final Drive Calculator — RPM at speed for any axle ratio, tire size and transmission. Compare gear ratios side by side and see what a taller tire does to your cruise RPM.
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 — Convert SAE wrench sizes to metric and back, or measure an unknown fastener with calipers to find the size you need.
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 & Selection Guide — Find the right converter stall speed for your build. Recommended flash stall range from your cam, a cruise RPM and lockup check, and a K-factor check for a converter you have.
Decimal to Fraction Inch Converter + Chart — Decimal to fraction inch converter with a full 1/64 inch chart, tap drill equivalents and SAE wrench sizes with metric equivalents.
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, with common engine torque ranges alongside so you can sanity-check the spec you are converting.
Temperature Converter (°F / °C / K) — Fahrenheit, Celsius, and Kelvin with engine reference points: coolant, oil, EGT zones (cold / normal / hot / danger).