--- The Excel file related to this article can be downloaded from Dependent Drop Down List 02 ---

In Article 15, we saw that our Dependent Data list can grow / reduce vertically but we had fixed the horizontal range. Now, we will remove this restriction and our data list can grow / reduce vertically as well as horizontally.

1. Prepare the formula for first drop down.

In article 15, we saw that it is very simple i.e. $F$1:$K$1. Let's assume that maximum it can grow till Z1. In this case, we need to prepare a formula which will give us a range of $F$1:$K$1 within the range of $F$1:$Z$1 if South America is selected. If another entry is added or deleted, it should adjust appropriately.

The formula in this case would be -

=OFFSET($F$1,0,0,1,COUNTA($F$1:$Z$1))

(Though OFFSET is a volatile formula but simplicity of OFFSET is a reason to use)

2. Prepare the formula for second drop down

The formula was already there, only change is that $K is replaced by $Z. (As I said earlier 12 is a number till which the list can grow. You can put any number say 100, 900 etc.)

=OFFSET(INDEX($F$1:$Z$12,,MATCH($A$2,$F$1:$Z$1,0)),1,0,
COUNTA(INDEX($F$2:$Z$12,,MATCH($A$2,$F$1:$Z$1,0))))

3. Create the first drop down list and second drop down list utilizing above formulas.

Select A2 > Data tab > Data Validation > Data Validation > Choose List in Allow: and in source put

=OFFSET($F$1,0,0,1,COUNTA($F$1:$Z$1))

Select B2 > Data tab > Data Validation > Data Validation > Choose List in Allow: and in source put

=OFFSET(INDEX($F$1:$Z$12,,MATCH($A$2,$F$1:$Z$1,0)),1,0,
COUNTA(INDEX($F$2:$Z$12,,MATCH($A$2,$F$1:$Z$1,0))))

Now, your dynamic drop down list which can grow vertically as well as horizontally is ready.