How Do Excel Macros Work?

If you've heard the word "macro" but aren't quite sure what's happening under the hood when one runs, you're not alone.

Contents:

1. Quick Answer

2. What a Macro Actually Is

3. How Excel Runs a Macro

4. How Macros Get Created

5. What Macros Can and Can't Do

Quick Answer

A macro is a saved sequence of actions written in a language called VBA (Visual Basic for Applications), which Excel reads and executes line by line. When you trigger a macro, Excel's built-in VBA engine works through that code and carries out each instruction, whether that's formatting cells, copying data, or opening another file. You don't need to know how to code to create a basic one, but understanding VBA lets you do a lot more.

What a Macro Actually Is

Think of a macro as a recipe. Each line of the recipe tells Excel to do one specific thing. When you run the macro, Excel follows the recipe from top to bottom.

That recipe is written in VBA, a programming language that's been built into Excel since the early 1990s. VBA lives inside every Excel workbook, in a hidden area called the Visual Basic Editor (VBE). You can open it with Alt + F11.

How Excel Runs a Macro

When you trigger a macro (by pressing a button, using a keyboard shortcut, or running it from the Developer tab), Excel hands the VBA code to its internal engine.

That engine reads each line one at a time and translates it into an action. A line that says Range("A1").Value = "Hello" tells the engine to go to cell A1 and put the word "Hello" in it. The engine does that, then moves to the next line.

This all happens nearly instantly, which is why macros that take actions on thousands of cells still run in seconds.

How Macros Get Created

There are two ways to create a macro.

The first is the Macro Recorder. You turn it on via the Developer tab, perform your actions in Excel normally, then stop the recording. Excel watches what you did and writes the VBA code for you automatically. It's a great starting point. (If you don't see the Developer tab, here's how to enable it.)

The second is writing VBA directly in the Visual Basic Editor. This takes more knowledge but gives you full control. You can add logic, loops, conditions, and anything else a macro recorder can't capture on its own. Our how to create a macro in Excel tutorial walks through this step by step.

Every macro starts with Sub MacroName() and ends with End Sub. Everything in between is the code Excel will run.

Sub SayHello()
    Range("A1").Value = "Hello"
End Sub

That's a complete, working macro. It puts the word "Hello" into cell A1.

What Macros Can and Can't Do

Macros can do almost anything you can do manually in Excel: format cells, sort data, create charts, open and save files, send data between sheets, and much more. They can also loop through thousands of rows in seconds and make decisions based on cell values.

What they can't do is reach outside of Excel's permissions. Macros respect your system's security settings, which is also why Excel warns you before opening a workbook that contains them.

One important thing: macro-enabled workbooks must be saved as .xlsm files. A standard .xlsx file strips out all VBA code on save.

If you want to go deeper into what VBA can do, the understanding objects in VBA post is a good next step. Objects are the core concept behind how VBA talks to Excel, and once that clicks, writing your own macros becomes a lot easier.