# Perform an inexact lookups (return a category/band)

### Rishi Sapra

Technical Community leader, speaker, trainer and evangelist specialising in Power BI and Azure. Formally recognised by Microsoft as a Most Valuable Professional (MVP), Fast Track Recognised Solution Architect (FTRSA) and Microsoft Certified Trainer (MCT).

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### Overview

An inexact Lookup allows us to define categories (by thresholds) and then lookup a value within these thresholds to return the category that our lookup value falls into. Perhaps an obvious example of this would be in terms of marks and grades – in the Topic Example Workbook above we have a series of exam marks and then in a separate table to the right a list of the lowest mark required to achieve each Grade (so any mark 80 or above is an A, anything between 70 and 79 is a B, 50 and 69 is a C and so on). It’s important that our grading structure is set to the lowest value of each threshold so in this case the lowest mark is 0.

We then have a list of marks (in Column B) which we want to lookup (against Columns G and H) and return the relevant grade in Column C. This can be achieved using an inexact lookup formula.

### Lookup Formulas with an inexact match

To do this we can use a VLOOKUP formula exactly as we did in the topic Using a VLOOKUP Function, though changing the last parameter in the function from FALSE (Exact match) to TRUE (Inexact Match).

The syntax of the VLOOKUP Formula is =VLOOKUP(“Lookup_Value”,”Table_Array”,”Col_index_Num”,”[Range_Lookup]”).

Our lookup value is the mark (e.g. the value in cell B2), our table Array is the range we want to look up in (e.g. G:H), the column index is the number of columns away from the first Column in our lookup range (Col G) the column you want to return values from is (Column H)- in this case 2.

So our completed VLOOKUP formula in cell C2 becomes =VLOOKUP(B2,G:H,2,TRUE) which returns the grade F indicating that the mark of 15 is greater than the lower threshold for grade F of 0 but less than the lower threshold for grade E which is 30.

As an alternative to a VLOOKUP we can use an inexact INDEX/MATCH function again just replacing the parameter with 1 (indicating that we want to return the first value less than) instead of 0 (indicating that we want to lookup an exact match).
The syntax of the MATCH Function is =MATCH(“Lookup_Value”,”Lookup_Array”,”Match_Type”)

Our Lookup value is the mark (e.g. cell B2), the lookup array is the column we want to find the mark in (Column F) and the match type is 1 indicating that we want a ‘Less than’ inexact match type. The INDEX Function =INDEX(“array”,”row_num”,”Column_num”)] then takes the column with the grades (Column G) as the array, the result from our MATCH as the row number and 1 as the Column number.
So our completed inexact INDEX/MATCH Function becomes =INDEX(G:G,MATCH(B2,F:F,1),1).

### Try it Out

In cells C2 to C6 of the Topic Example Workbook, return the grade corresponding to each relevant mark in column B using a VLOOKUP function as per above.

In cells D2 to D6 do the same thing using an INDEX/MATCH function.

A demonstration is shown in the video clip below. Resist the temptation to view the answers file below until you have tried this!