# What are control limits on a control chart?

Category:
business and finance
business operations

The

**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**.

**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.

**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.