Create a Custom Excel Function to Replace Formulas with Multiple IF Functions

Multiple Nested IF Functions

Do you get tied up in a knot trying to write – let alone explain – a formula that has one IF Function nested inside another, and another…? I know that I do! And, what happens when your sales manager wants to revise the tiers for the quantity discounts? How many hours will this take you to review your logic and to make all of those multiple changes?

Usually, this will mean a lot of time, a lot of frustration and possibly some resentment thrown in as well!

Well, relax. I am going to demonstrate how easy it is to write a custom function in Excel using the “Select Case” Construct to replace the “rat’s nest” of multiple IF Functions in your formulas!

Scenario for this Function

You have been asked by your Sales Manager to write a formula to grant a discount, based upon the quantity of units ordered. There are 5 Tiers: Below 5 units ordered, no discount. From 6 to 24 units, a 10% discount, etc. Rather than spending a half hour nesting IF() functions and using AND() functions to create this formula, spend less than 10 minutes creating a Custom Excel Function instead.

Create the Custom Excel Function

Begin by opening the Visual Basic Editor. One way to do this is right-click any worksheet tab and select “View Code.”
Ensure that you have inserted a Module in the Project Explorer and that you have selected the module.
In the example that I use on this video tutorial, my first line of code is: “Function DiscQty(quantity)” and this is matched to an “End Function” statement
For this Custom Function, I am using the “Select Case” Construct in Visual Basic (VBA). Think of the keyword “Case” as a substitute for the =IF() Function.
Rather than nesting the Excel =AND() Function inside the IF() Function, you will substitute – e.g. “Case 6 To 24” and then “DiscQty = 0.1” to indicate a 10% discount for quantities between 6 AND 24.

Watch the video to see how easy is is to create – and use – this custom Excel function. Invest the 7 minutes and 47 seconds to watch it – I guarantee that this investment of time will pay you many dividends for years and years to come!