Spring Rate Converter

Q: How do I convert 10,000 N/mm to lbs/in spring rate?

10,000 N/mm equals 57,100 lbs/in . To convert the spring rate in N/mm to a value in lbs/in: Write down the known number. In this case, it’s 10,000 N/mm . Multiply it by the factor 5.71 . The product equals 57,100 . The result with the unit is 57,100 lbs/in .

Q: How do I convert spring rate from N/mm to kg/mm?

To convert the spring rate in N/mm to kg/mm, you need to divide the value by 9.807 . Although both units are commonly used for spring rates, they are technically not equivalent. For the kg/mm unit, we use a mental shortcut to describe the gravitational force exerted by an object with the given mass.

Q: What spring rate do I need?

The optimal spring rate depends on the application. For bikes , the typical spring stiffnesses range from 200 to 600 lbs/in . For a regular passenger car , the common spring rates vary from 300 to 1000 lbs/in . However, to choose the perfect spring stiffness, it’s always best to ask an expert at the dealership.

Creators

Wojciech Sas, PhD

Wojciech SasPhD, Institute of Physics in Zagreb

Wojciech, PhD, is a physicist at the Institute of Physics in Zagreb, investigating materials under extreme conditions such as low temperatures and high pressures. He specializes in experimental work, including participation in Large-scale User Facilities such as synchrotrons. Wojciech uses his experience and knowledge to create calculators in physics, math, and statistics categories. In his free time, he likes swimming, playing board games, and looking for meteors while stargazing. See full profile

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Reviewers

Steven Wooding

Steven Wooding is a physicist by training with a degree from the University of Surrey specializing in nuclear physics. He loves data analysis and computer programming. He has worked on exciting projects such as environmentally aware radar, using genetic algorithms to tune radar, and building the UK vaccine queue calculator. Steve is now the Editorial Quality Assurance Coordinator here at Omni Calculator, making sure every calculator meets the standards our users expect. In his spare time, he enjoys cycling, photography, wildlife watching, and long walks. See full profile

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This is Omni Calculator’s spring rate converter — a straightforward tool that helps you convert spring rate to many spring stiffness units. Our calculator supports the following spring rate conversions:

lbf/in to N/mm;
kg/mm to lbf/in;
N/mm to kg/mm;
N/mm to lbf/in; and
Many more!

Read on to understand what spring rates are and how to calculate the stiffness of a spring.

What are spring rates?

Spring rate, or spring stiffness, is a spring’s resistance to an applied force. To learn how to calculate the spring rate, you can check our spring rate calculator.

There are different spring rate units that we commonly use. The most popular are:

N/m (newton per meter);
lbf/in (pounds-force per inch);
kips/in (kilopounds per linear inch);
N/mm (newtons per millimeter);
kg/mm (kilograms per millimeter); or
J/m² (joules per square meter).

How to use spring rate converter

With our tool, you’ll find any spring rate conversion in no time. Here are the steps to follow:

Find the spring stiffness unit that you already have.
Type the value in the field with this unit.
That’s all! The remaining spring rates for other units will be displayed instantly.
You can repeat the process with any other input and get the desired answer.

🔎 If you want to learn more about springs and their properties, you should try Omni’s spring calculator.

lbf/in to N/mm and N/mm to lbf/in spring rate conversion

To convert between the two most commonly used spring rate units, we need to remember just two formulas.

To convert from lbf/in to N/mm:

spring rate [N/mm] = 0.17513 × spring rate [lbf/in]

To convert from N/mm to lbf/in:

spring rate [lbf/in] = 5.71 × spring rate [N/mm]

🙋 If you are into physics or engineering, you may also find our torsional stiffness calculator useful.

FAQs

How do I convert 10,000 N/mm to lbs/in spring rate?

10,000 N/mm equals 57,100 lbs/in.

To convert the spring rate in N/mm to a value in lbs/in:

Write down the known number. In this case, it’s 10,000 N/mm.
Multiply it by the factor 5.71.
The product equals 57,100.
The result with the unit is 57,100 lbs/in.

How do I calculate stiffness of a spring?

To calculate spring stiffness (or spring rate), you need to divide the applied force by the spring’s displacement. For example, if the spring contracts by 1 mm under a compression force of 30 N, then the spring stiffness is 30 N/mm.

How do I convert spring rate from N/mm to kg/mm?

To convert the spring rate in N/mm to kg/mm, you need to divide the value by 9.807. Although both units are commonly used for spring rates, they are technically not equivalent. For the kg/mm unit, we use a mental shortcut to describe the gravitational force exerted by an object with the given mass.

What spring rate do I need?

The optimal spring rate depends on the application. For bikes, the typical spring stiffnesses range from 200 to 600 lbs/in. For a regular passenger car, the common spring rates vary from 300 to 1000 lbs/in. However, to choose the perfect spring stiffness, it’s always best to ask an expert at the dealership.