Table of Control Chart – Constants A2 d2 D3 D4

Control Charts

Control charts are used to calculate control limits and estimate the process standard deviation. Control chart constants used are D4, D3, A2, and d2 (These control chart constants depend on the subgroup size n).

These control chart constants are summarised in the table below. For example, if your subgroup is 4, then D4 = 2.282, A2 = 0.729, and d2 = 2.059.

There is no value for D3. This simply means that the R chart has no lower control limit when the subgroup size is 4.

Sub group Size (n)A2D3D4d2
21.880 3.2671.128
31.023 2.5741.693
40.729 2.2822.059
50.577 2.1142.326
60.483 2.0042.534
70.4190.0761.9242.704
80.3730.1361.8642.847
90.3370.1841.8162.970
100.3080.2231.7773.078
110.2850.2561.7743.173
120.2660.2841.7163.258
130.2490.3081.6923.336
140.2350.3291.6713.407
150.2230.3481.6523.472
160.2120.3641.6363.532
170.2030.3791.6213.588
180.1940.3921.6083.640
190.1870.4041.5963.689
200.1800.4141.5863.735
210.1730.4251.5753.778
220.1670.4341.5663.819
230.1620.4431.5573.858
240.1570.4521.5483.895
250.1530.4591.5413.931

3 thoughts on “Table of Control Chart – Constants A2 d2 D3 D4

  1. Kanika Yadav

    Thanks

  2. Bao

    Values greater than 25?

    • Gaurav Yadav

      Will update the article soon

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