How to calculate the sag in your chain? Use this tool to determine the sag in a chain based on various factors such as weight, span length, and tension. The calculator simplifies the complex calculations involved in determining how much a chain will sag under its own weight and the tension applied to it.

## Chain Sag Calculator

**What Is Chain Sag?**

How necklace chains don’t hang perfectly straight when attached at both ends? There’s a slight dip in the middle. Bicycle chains do the same thing due to their weight. This dangling effect is called sag. To picture it, imagine stretching a necklace tautly between two pushpins. It wouldn’t lie flat against the wall—there’d be some droop. The tighter or looser you pull the links impacts sag too. Keeping an eye on your chain’s sag is important for smooth riding, as too much could lead to slipping.

### The Formula

The sag of a chain can be calculated using the following formula:

`$S=\frac{w\times {l}^{2}}{8\times T}$`

**Variables**

Variable |
Description |
Unit |
---|---|---|

S |
Chain Sag | inches |

w |
Weight per Unit Length | pounds/inch |

l |
Length of the Span | inches |

T |
Total Tension | pounds |

### How to Use the Calculator?

There are two modes available: **Basic Calc** and **Advanced Calc**. Depending on your needs, you can choose either mode to perform your calculations.

**Using Basic Calc Mode**

In the Basic Calc mode, you can enter any three of the following values to calculate the missing one:

**Weight per Unit Length (w)**: Enter the weight of the chain per unit length. For example, if your chain weighs 0.5 lb/in, enter`0.5`

into the field labeled “Weight per Unit Length (lb/in)”.**Length of the Span (l)**: Enter the length of the span between the two supports. For example, if the span is 120 inches, enter`120`

into the field labeled “Length of the Span (in)”.**Total Tension (T)**: Enter the total tension applied to the chain. For example, if the tension is 150 lbs, enter`150`

into the field labeled “Total Tension (lb)”.**Chain Sag (S)**: Enter the chain sag if you already know it, or leave this field empty to calculate the sag.

**Using Advanced Calc Mode**

The Advanced Calc mode allows you to calculate the **Adjusted Chain Sag** by considering an additional factor:

**Temperature Factor**: Enter the temperature factor as a percentage to adjust for environmental conditions. For example, if the temperature factor is 5%, enter`5`

into the field labeled “Temperature Factor”.

**How To Calculate Chain Sag**

Let’s go through two example calculations to illustrate how the Chain Sag Calculator works.

**Example 1: **

For example we have the following information:

**Weight per Unit Length (w)**: 0.6 lb/in**Length of the Span (l)**: 100 inches**Total Tension (T)**: 200 lbs

$S=\frac{0.6\times 10{0}^{2}}{8\times 200}$

`We want to calculate the chain sag S.`

1: Plug the values into the formula:

2: Calculate the length squared:$10{0}^{2}=10000\text{inches}$

3: Multiply by the weight per unit length:$0.6\times 10000=6000\text{lb-inches}$

4: Divide by 8 times the total tension:

`So, the chain sag `

`S is `**3.75 inches**.

**Example 2: Adjusted Chain Sag with Temperature Factor**

Now, let’s calculate the adjusted chain sag with a temperature factor. Suppose we have:

**Weight per Unit Length (w)**: 0.4 lb/in**Length of the Span (l)**: 150 inches**Total Tension (T)**: 250 lbs**Temperature Factor**: 10%

**1**: First, calculate the basic chain sag using the formula:

**2**: Calculate the length squared:

**3**: Multiply by the weight per unit length:

**4**: Divide by 8 times the total tension:

**5**: Adjust for the temperature factor:

`$\text{AdjustedSag}=4.5\times (1+0.10)=4.5\times 1.10=4.95\text{inches}$`

So, the adjusted chain sag is **4.95 inches**.

### Final Words

The Chain Sag Calculator helps you figure out how much a chain will hang down when it’s stretched between two points. It’s really useful for people working with chains in factories or even for simple projects at home