Twist Per Inch Calculator

TPI from fiber type and desired yarn characteristics.

Target WPI

Twist multiplier

Number of plies

Staple length (in)

Tab to move between fields

TPI (calculated)

18.83

TPI (balanced rule)3.46

Twist angle (°)78.5

Singles TPI18.83

Plying TPI13.31

Twists per staple75.3

Approx yarn count (Ne)22.15

How to Use This Calculator

Enter the target WPI (wraps per inch) of your yarn.
Set the twist multiplier for your fiber: wool worsted 3.5–4.5, woolen 4.5–6, cotton 3.5–4.5, silk 2.5–3.5.
Enter the number of plies for the finished yarn.
Enter the staple length in inches of your fiber.
Read the calculated TPI and the balanced-rule TPI as two complementary starting points.
Check the twists per staple output — a value above 1 confirms sufficient twist for yarn integrity.

How the result changes with Target WPI

Target WPI: Wraps per inch of your target yarn — determines approximate yarn count.
Twist multiplier: Fiber-dependent factor: wool worsted 3.5-4.5, woolen 4.5-6, cotton 3.5-4.5, silk 2.5-3.5.
Number of plies: Number of singles plied together (1 for singles yarn).
Staple length (in): Average fiber staple length in inches — affects minimum twist needed.

TPI (calculated): Twist per inch using the twist multiplier × √Ne formula.
TPI (balanced rule): TPI from the √WPI rule of thumb for balanced singles.
Twist angle (°): Approximate helix angle of the twist.
Singles TPI: Recommended TPI for each single when plying.
Plying TPI: Recommended plying twist (singles TPI ÷ √plies).
Twists per staple: Total twists across one staple length — should be > 1 for yarn integrity.
Approx yarn count (Ne): Estimated English cotton count from WPI.

Identify Input Parameters
4 parameters
Target WPI = 12, Twist multiplier = 4, Number of plies = 2, Staple length (in) = 4 = 4 input(s) provided
Calculate TPI
TPI = twistMultiplier * sqrt(neApprox)
18.83 = 18.83
Calculate TPI
TPI = sqrt(wpi)
3.46 = 3.46
Calculate Twist angle
78.5 = 78.5