Understanding the VLOOKUP Function

Excel has a huge number of different worksheet functions—some of them used quite often, and others quite obscure. One of the more obscure functions (at least for Excel novices) is the VLOOKUP function. Understanding how this function works can make your life much simpler, especially when dealing with tables of data and pulling information from those tables.

VLOOKUP is a shortened form of "Vertical Lookup." It is a function that looks vertically (up and down) through a data table and extracts information from the table as you direct. For instance, let's assume you have a data table that lists part numbers and their prices. The part numbers are in column H, and the prices for those parts are in column I. (Assume the data table is in the range H5:I27.) You can use the following formula to look up a part number (located in cell C28) and return its price:

=VLOOKUP(C28,H5:I27,2)

Notice that, at a minimum, VLOOKUP requires three arguments. The first is the value that you want to look up. In this case, C28 contains the part number to be matched in the data table. The second argument is the actual data table, in this case H5:I27. The third argument specifies from which column of the table the value should be returned. In this case I wanted the price, which was in the second column (column I) of the data table.

What VLOOKUP does, in this instance, is to take the value in C28 and then try to match it to a cell in the first column of the range H5:127. If it finds a match, then it returns the value from column 2 of that range—the price we wanted.

VLOOKUP will also accept an optional fourth argument, which can be either TRUE or FALSE. The default value for the argument is TRUE, which means that VLOOKUP will approximate values when matching them in the data table. If an exact match cannot be found in the data table, then VLOOKUP considers the next lowest value in the first column of the table to be a match. Thus, if you are looking for a part number such as "P23," and there is no such part number in the table, but there is a "P22," then VLOOKUP considers that a match. If you set the optional fourth argument to FALSE, then VLOOKUP only returns successfully if it can make an exact match.

Because of the way in which VLOOKUP does its matching, it is very important that the information in your data table be sorted in ascending order according to the values in the first column.