SHOP REFERENCE / CALCULATORS
Universal Shop Calculator
Quick calculations for the bench, toolbox and machine shop. Results update as you type; displayed values are rounded. Enter numbers without unit suffixes and choose the units below. Inches also accept 3/8, 1 1/2 and 1-1/2.
Decimal / Fraction / Metric Converter
Convert inches and millimeters using exactly 25.4 mm per inch. Fractions round to the selected shop increment; error is rounded size minus entered size.
Thread Pitch ↔ TPI
Pitch (mm) = 25.4 ÷ TPI. These are mathematical conversions, not necessarily standard thread sizes.
Torque Unit Converter
Convert one torque value to ft-lb, in-lb, N·m and kgf·m. kgf·m means kilogram-force meter.
Nearest Standard Drill Size Finder
Match nominal drill diameters across fractional, number, letter and metric series. Coverage: 1/64–1 in (64ths), #97–#1, A–Z, and all metric entries in the Gühring chart (0.05–25.4 mm), plus verified 6.35 mm. Dimensional matching only, not a tap-drill recommendation.
RPM / Cutting Speed Calculator
Imperial: RPM = SFM × 12 ÷ (π × diameter in inches). Metric: RPM = m/min × 1000 ÷ (π × diameter in mm). Supply your own cutting speed. Optional milling feed = RPM × chip load per tooth × flute count. Use in/tooth for Imperial and mm/tooth for metric. Leave both feed inputs blank to skip feed rate.
Related tools & data sources
Metric to SAE chart · Tap drill chart · Thread identifier · Pipe thread guide
Drill diameters: Gühring Decimal Equivalents chart (all entries, page 1); Gühring 6.35 mm drill specification. Fractional and metric nominal dimensions are converted exactly rather than using the chart’s rounded inch equivalents. Number and letter values use the published decimal-inch sizes.
Length and torque conversions: NIST SP 811 Appendix B.9. Full-precision lbf factors use 0.45359237 kg per pound, standard gravity 9.80665 m/s² and 0.3048 m per foot. Cutting speed and milling feed relationships: Harvey Performance — Speeds and Feeds 101 and Gühring chart page 2. RPM uses exact π rather than the rounded 3.82 multiplier.
Sources verified October 8, 2026. Chart coverage is finite; specialty/custom diameters and manufacturing tolerances are not included. Positive differences mean larger than target. Equally near sizes are shown together. Confirm actual fit and tooling limits.