Yarn Twist Multiplier & TPI Calculator

Spinning engineering & yarn mechanics: Compute Turns Per Inch ($TPI$), Turns Per Meter ($TPM$), Twist Multiplier ($TM$ / $\alpha_e$), and surface helix angle.

Yarn Parameters

Yarn Count (Ne_c): English Cotton count

Twist Multiplier TM (α_e): Standard warp TM ~3.8–4.4

Fiber Type & Density (g/cm³): Used for yarn diameter & helix angle

Packing Factor (φ): Fiber volume fraction (typically 0.55–0.65)

Twist Direction:

Z-Twist (Right-hand / Standard Single) S-Twist (Left-hand / Plied / Specialty)

Recommended Twist Multipliers (TM)

Soft Knitting Yarn: TM = 3.0 to 3.4 (soft handle, low spirality)
Hosiery / Weft Yarn: TM = 3.4 to 3.8 (balanced strength and softness)
Warp Weaving Yarn: TM = 4.0 to 4.5 (maximum tensile & abrasion resistance)
Voile / Crepe / High-Twist: TM = 5.5 to 7.5 (pebble grain, crisp texture)

Twist Density Results

Turns Per Inch (TPI)

Turns Per Meter (TPM)

Twist Factors in Other Systems

Metric Twist Factor (α_m)

TPM = α_m × √Nm

Tex Twist Factor (α_tex)

TPM × √Tex / 100

Geometry & Mechanics

Estimated Yarn Diameter: --

Surface Helix Angle (θ): --

Yarn Character / Application: --

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