What Is a Function in Excel? Arguments Explained

What is a function in Excel? It's a built-in calculation with a name, such as SUM, AVERAGE or IF, that takes inputs and returns a result. Instead of typing =B2+B3+B4+B5+B6, you write =SUM(B2:B6) and Excel does the work. This guide explains the parts of a function, what arguments are, and how to enter and combine functions, using one small table you can type in yourself.

What is a function in Excel?#

A function is a ready-made calculation that Excel already knows how to do. Each one has a name that says what it does: SUM adds, AVERAGE finds the mean, MAX finds the biggest value, and IF chooses between two results.

All examples in this guide use these test scores in A1:B6:

Excel has several hundred functions in categories like Math, Text, Date and Time, Lookup and Logical. You don't need most of them. A handful covers everyday work and most job tests.

Function vs formula: what's the difference?#

A formula is any calculation in a cell that starts with an equals sign. A function is one named tool you can use inside a formula.

• =B2-B3 is a formula with no function. It uses the minus operator. See how to subtract in Excel.
• =SUM(B2:B6) is a formula that uses one function.
• =SUM(B2:B6)/5 is a formula that mixes a function and an operator.

Functions save time and avoid mistakes. Adding 500 cells with + is slow and easy to get wrong, but =SUM(B2:B501) is one short formula. If you've never typed a formula before, start with how to write your first Excel formula.

The parts of a function: name, brackets and arguments#

Every function follows the same pattern, called its syntax:

=FUNCTION_NAME(argument1, argument2, ...)

Arguments are the inputs a function needs. SUM needs at least one: the numbers or range to add. IF needs a test, a result for TRUE and a result for FALSE:

=IF(B2>=70,"Pass","Fail")

For Amara's 72, this returns Pass. For Dmitri's 64, it returns Fail. The IF function guide covers each argument in detail.

Some arguments are optional. When you type a function, Excel shows a tooltip, and optional arguments appear in square brackets, such as SUM(number1, [number2], ...). You can leave those out.

In some countries, Excel uses a semicolon between arguments instead of a comma: =IF(B2>=70;"Pass";"Fail"). This depends on your regional settings. The function works the same way.

What kinds of arguments can a function take?#

An argument can be almost any value Excel understands. The most common types are:

• A number: =ROUND(77.8,0) returns 78.
• A cell or range: =SUM(B2:B6). A range is a block of cells, written as first cell, colon, last cell.
• Text in double quotes: "Pass". Without quotes, Excel thinks Pass is a name and shows #NAME?.
• A logical test: B2>=70, which is either TRUE or FALSE.
• Another function: =ROUND(AVERAGE(B2:B6),0). This is called nesting.

How to enter a function in Excel#

You can type a function, pick it from a list, or let Excel write it.

1. Type it. Click a cell, type =SU, and Excel shows a list of matching names. Press Tab to pick SUM, then type the arguments and the closing bracket.
2. Use AutoSum. Click the cell below a column of numbers and press Alt+= on Windows or ⌘+Shift+T on a Mac. Excel writes =SUM(...) and guesses the range. Press Enter if the range is right. The SUM function guide shows more ways to add.
3. Use Insert Function. Click the fx button next to the formula bar, or press Shift+F3. A window lets you search for a function and fills in each argument in its own box.

While you type, the tooltip under the cell shows the argument you're on in bold. It's the fastest way to remember the order.

How to put one function inside another#

You can use a function as an argument of another function. This is called nesting. Excel works from the inside out.

=ROUND(AVERAGE(B2:B6),0)

First AVERAGE returns 77.8. Then ROUND takes 77.8 as its first argument and rounds it to 0 decimal places, giving 78. Each function needs its own pair of brackets, so count them: two opening, two closing.

Here is a nested IF that adds a third result:

=IF(B2>=85,"Merit",IF(B2>=70,"Pass","Fail"))

Ben's 85 returns Merit, Amara's 72 returns Pass and Dmitri's 64 returns Fail. Functions like these are the base of real work such as an Excel timesheet and of most questions in a basic Excel test for employment.

Common mistakes when using functions#

Most function errors come from typing, not from the function itself:

1. No equals sign. SUM(B2:B6) without = is just text.
2. A misspelled name. =SUMM(B2:B6) returns #NAME?.
3. Text without quotes. =IF(B2>=70,Pass,Fail) returns #NAME?.
4. Missing brackets. Excel may offer a fix, but check it matches what you meant.
5. Arguments in the wrong order. In IF, the test comes first. Use the tooltip to check.

Practise it#

Functions make sense once you've typed a few yourself. Practise your first formulas in a live spreadsheet: you start with =, build simple calculations and see them recalculate. Then move on to the SUM and AutoSum lesson, where every answer is checked instantly. For more short tasks, try these Excel exercises for beginners, or start with the nested ROUND and AVERAGE exercise on this page.