Do Quick Calculation!

Perform fast calculations with our user-friendly online calculator! Conveniently crunch numbers and solve equations instantly. Ideal for quick math tasks, our tool simplifies your daily computations effortlessly. Try our intuitive calculator for accurate results on the go!

Thread Pull Out Force Calculator

Calculate thread pull out force easily online. Use our fast, accurate Thread Pull Out Force Calculator for steel, aluminum & metric threads.

If you've ever wondered how much force a threaded connection can handle before it strips or fails, you're in the right place. The Thread Pull Out Force Calculator is a simple online tool we developed to help engineers, mechanics, DIYers, and students accurately calculate the thread pullout strength of bolts and screws in various materials like steel, aluminum, or plastic.

With support for both imperial and metric units, and multiple calculation methods including NASA, stress-area-based, and ISO standards, this calculator makes the task easy, fast, and accurate.

What Is Thread Pull Out Force?

Thread pull out force is the maximum force that can be applied to a bolt or screw before the threads strip or fail by pulling out from the material. This type of failure often happens when the threads of the weaker material (typically the female side) can no longer resist the shear stress caused by the fastener under load.

Understanding this force is crucial in applications where safety and durability are important, such as in automotive, aerospace, construction, or machine design.

How to Calculate Thread Pull Out Force

There are several accepted formulas for calculating thread pullout strength. Each depends on the accuracy needed and the material involved.

1. NASA Method (Quick Estimate)

P = π × d × Fs × L / 3

Where:

  • P = Pull out force
  • d = Mean or pitch diameter (in inches or mm)
  • Fs = Shear strength of the weaker material
  • L = Thread engagement length

This formula includes a built-in safety factor of 3. It's ideal for quick and conservative estimates.

2. Stress-Area Based Method

P = (As × S) / SF

As = Factor × π × d × L

Where:

  • As = Shear area
  • S = Shear strength
  • SF = Safety factor (user defined)

This method allows for a customizable safety factor and is widely used in engineering calculations.

3. ISO/High Precision Method

P = 0.5 × π × d × L × τ

Where:

  • d = Mean or pitch diameter
  • L = Effective engagement length
  • τ = Shear strength of the female material

This formula is highly accurate and used in critical applications following ISO standards.

How to Use the Thread Pull Out Force Calculator

Using our calculator is simple and requires just a few steps:

Step 1

Enter the thread diameter (in mm, cm, or inches).

Step 2

Enter the length of thread engagement in your preferred unit.

Step 3

Input the shear strength of the weaker material (like aluminum or plastic).

Step 4

Select the calculation method you want to use: NASA, stress-area based, or ISO standard.

Step 5

Choose your input and output units, including lbf, N, kN, and kgf.

Step 6

Click “Calculate” and get your thread pull out force in multiple units instantly.

The tool will also show you the exact formula used for full transparency.

When to Use This Calculator

This calculator is perfect for:

  • Mechanical design verification
  • Engineering prototypes
  • Selecting fasteners for aluminum or soft materials
  • Comparing thread engagement strategies
  • Educational purposes for engineering students

Whether you're calculating pull out force for a steel bolt or checking thread strength in 3D printed plastic, this calculator simplifies everything.

Final Verdict

Our Thread Pull Out Force Calculator is designed to be both accurate and user-friendly. It supports metric and imperial units, includes three standard methods, and converts results into multiple formats. Whether you're working with steel, aluminum, or composite materials, this calculator gives you the numbers you need fast.

Don’t waste time doing complex hand calculations. Use our tool to calculate thread stripping strength with confidence.

Frequently Asked Questions (FAQs)

How do you calculate thread pullout force?

You can calculate thread pullout force using the formula:

P = π × d × Fs × L / 3

This is the NASA-based method and includes a built-in safety margin.

What is the formula for stripping force?

Stripping force is another term for pull out force. It’s calculated by multiplying the shear area of the threads by the material’s shear strength and dividing by a safety factor.

Can this calculator work for metric threads?

Yes, the calculator supports metric inputs like mm, cm, and converts them to inches internally for calculation.

Can I use this calculator for aluminum?

Absolutely. Just input the shear strength of aluminum (typically around 20,000 psi) and the rest of the calculation will work the same.

Does this calculator use a safety factor?

Yes. The NASA method uses a built-in factor of 3, and the stress-area method lets you choose your own.