Engineering Calculators

The calculations engineers reach for most often when selecting fasteners, in one place: tap drill size, hardness conversion, tightening torque, stress and shear checks, length and thread engagement. Free to use, no sign-up, results as you type.

01

Metric Tap Drill Diameter

Quick tap drill size for ductile and brittle materials using the standard formula — a handy reference for machining.

Choose the parameters and press Calculate drill size
Formula Ductile (steel/brass): D = nominal diameter − pitch; brittle (cast iron/bronze): D = nominal diameter − 1.05 × pitch
02

Metal Hardness Conversion HRC / HB / HV

Convert between the three hardness scales for carbon and alloy steel, fitted to GB/T 1172. Results are approximate.

Enter a value to convert
Note Applies to carbon and alloy steel only. Values are approximate; certified material reports must be based on laboratory measurement.
03

Inch UNC / UNF Bolt Torque

Tightening torque for ASTM A325/A490 inch bolts, output in both lbf·ft and N·m.

Choose the parameters to calculate torque
Note Output in lbf·ft and N·m. For assembly guidance only — follow the equipment specification for critical joints.
04

Bolt Tensile Stress & Load Check

Actual tensile stress from σ=F/As, compared against 0.75 × yield to judge whether the joint is safe.

Enter the load to check the joint
Formula Tensile stress σ = F / As (As = tensile stress area of the thread); safe when σ ≤ yield strength × safety factor (0.75 by default)
05

Length Unit Converter (Metric / Imperial)

Convert mm, cm, m, inches and feet in one click — handy for fastener dimensions.

Waiting for a value
Basis 1 inch = 25.4 mm, for quick conversion of fastener dimensions.
06

Metric Bolt Tightening Torque

Recommended tightening torque from T=K×Ff×d, with preload taken at 75% of yield by default.

Enter the parameters and calculate
Formula T = K × Ff × d; preload Ff defaults to 75% of yield; applies to standard metric coarse threads.
07

Bolt Shear Strength Check (single shear)

Single-shear stress τ=F/A against shear yield, with the resulting safety factor and a risk verdict.

Enter the parameters and calculate
Formula Shear area A = π·d²/4; τ=F/A; shear yield of steel ≈ 0.577 × tensile yield; a single shear plane is assumed.
08

Minimum Thread Engagement Length

Minimum engagement from Le≈d×k, plus a 10% engineering margin to prevent thread stripping in blind holes.

Choose the parameters and calculate
Formula Minimum engagement Le ≈ d × k, where k is the material factor; aluminium and magnesium parents need deeper engagement. A 10% engineering margin is recommended.
09

Bolt Length Selection (through hole with nut)

Theoretical length from plate thickness + washer + nut + 2 × pitch, with a prompt to round up to the next standard length.

Enter the parameters and calculate
Formula Theoretical length = plate thickness + washer + nut height + 2 × pitch (2–3 threads showing past the nut); round up to the next standard length.
10

Joint Slip Safety Factor

Compares Fpre×μ with the transverse load and returns a slip safety factor for friction-grip joints.

Enter the parameters and calculate
Formula Maximum friction Ffriction = Fpre × μ; slip safety factor S = Ffriction / Ftrans; S ≥ 1.2 is the safe engineering range.

Please note: all results above are theoretical reference values. Adjust them for the actual workpiece material, application and equipment specification before machining or assembly.

For standard part selection, custom parts or technical advice, contact us for a quote.