# What are control limits on a control chart?

**control chart**is a graph used to study how a process changes over time. Data are plotted in time order. A

**control chart**always has a central line for the average, an upper line for the upper

**control limit**, and a lower line for the lower

**control limit**. These lines are determined from historical data.

Also to know is, what are warning limits on a control chart?

Definition of **Warning Limits**: In a **control chart**, if **control limits** are placed at two times the standard deviation from the process average then the **limits** are said to be **Warning Limits** or Two Sigma **Limits**.

Beside above, what do control limits represent? The **control limits** of your **control chart represent** your process variation and help indicate when your process is out of **control**. **Control limits** are the horizontal lines above and below the center line that are used to judge whether a process is out of **control**.

Likewise, how do you find the control limit on a control chart?

**Control limits are calculated by:**

- Estimating the standard deviation, σ, of the sample data.
- Multiplying that number by three.
- Adding (3 x σ to the average) for the UCL and subtracting (3 x σ from the average) for the LCL.

What is control limits and specification limits?

**Specification limits** are the targets set for the process/product by customer or market performance or internal target. In short it is the intended result on the metric that is measured. **Control limits** on the other hand are the indicators of the variation in the performance of the process.