5 Viral Excel Mistakes (and How to Avoid Them)

We’ve all been there. You’re in the middle of a crucial Excel task, and suddenly something goes wrong. Maybe your formula doesn’t work, your numbers don’t add up, or—worst of all—you’re left staring at an error message you don’t understand.

Excel is powerful, but even the best of us make mistakes. Some of these errors are so common they’ve practically gone viral in offices everywhere.

Today, we’ll tackle 5 viral Excel mistakes that trip people up again and again—and, more importantly, how to avoid them.

1. Copy-Pasting Without Formatting Control

The Mistake: You copy data from one sheet to another, but the formatting turns into a disaster. Suddenly, you’re dealing with mismatched fonts, broken borders, and random colors.

Why It’s a Problem: Uncontrolled formatting can make your workbook messy and hard to navigate, especially when sharing it with others.

How to Fix It: Use Paste Special to control exactly what gets copied.

• Shortcut: Press Ctrl + Alt + V after copying and select "Values" to paste only the numbers, not the formatting.

2. Forgetting to Lock Cells in Formulas

The Mistake: You’re dragging a formula down a column, but instead of working properly, it breaks. Why? Because you forgot to lock the reference.

Why It’s a Problem: This leads to incorrect calculations, wasted time troubleshooting, and even bigger problems in reports.

How to Fix It: Use absolute references by adding $ before the row or column you want to lock.

• Example: Instead of A1, use $A$1 to lock both the row and column.

3. Ignoring Data Validation

The Mistake: You’re manually entering data into a sheet, but someone else enters “abc” where there should be a number. Now your formulas break, and you have no idea why.

Why It’s a Problem: Incorrect inputs can ruin your calculations and make your reports unreliable.

How to Fix It: Set up Data Validation rules:

1. Go to Data > Data Validation.
2. Choose the type of input you want (e.g., numbers, dates, specific text).
3. Add an error message to guide users.

4. Overlooking Named Ranges

The Mistake: You’re working with a formula that looks like this: =SUM(A1:A100)

Now imagine this formula in a sheet with hundreds of rows and columns. It’s easy to get lost or accidentally break something.

Why It’s a Problem: Relying on cell references makes your formulas hard to read and understand, especially when collaborating with others.

How to Fix It: Use Named Ranges to make your formulas clearer.

1. Highlight your range, then go to Formulas > Define Name.
2. Name it something meaningful (e.g., "SalesData").
3. Replace your formula with =SUM(SalesData).

5. Failing to Audit Formulas

The Mistake: You inherit a workbook full of formulas, but something doesn’t add up. Instead of fixing it, you spend hours trying to reverse-engineer someone else’s work.

Why It’s a Problem: Hidden errors in formulas can lead to incorrect results and wasted time troubleshooting.

How to Fix It: Use Excel’s built-in Formula Auditing Tools:

1. Go to Formulas > Trace Precedents to see which cells are feeding into a formula.
2. Use Trace Dependents to find where the results are being used.

Your Turn: Test Your Skills

Which of these mistakes have you made recently?

Try applying one of the fixes above to your current projects. And if you’ve got a tip for avoiding Excel errors, reply to this email, I’d love to share it in an upcoming edition!