XBar and S Chart Factors for Control Limits

The values for samples ranging in size from 0 to 25 for XBar and S charts are:

 
Chart for Averages

Chart for Standard
Deviations

Sample Size

A3

B3

B4

0

 

0.000

 

1

 

0.000

 

2

2.659

0.000

3.268

3

1.954

0.000

2.568

4

1.628

0.000

2.266

5

1.427

0.000

2.089

6

1.287

0.030

1.970

7

1.182

0.118

1.882

8

1.099

0.185

1.815

9

1.032

0.239

1.761

10

0.975

0.284

1.726

11

0.927

0.321

1.679

12

0.886

0.354

1.646

13

0.850

0.382

1.618

14

0.817

0.406

1.594

15

0.789

0.428

1.572

16

0.763

0.448

1.552

17

0.739

0.466

1.534

18

0.718

0.482

1.518

19

0.698

0.497

1.503

20

0.680

0.510

1.490

21

0.663

0.523

1.477

22

0.647

0.534

1.466

23

0.633

0.545

1.455

24

0.619

0.555

1.445

25

0.606

0.565

1.435

More information

XBar-R, XBar-S, R, S and X chart calculations.