In Excel: select the range, then Home ▸ Conditional Formatting ▸ Highlight Cells Rules ▸ Duplicate Values, and pick a fill colour.
On this page7
Select the cells to check (drag over B2:B20, or click a column header for the whole column).
On the Home tab, open Conditional Formatting ▸ Highlight Cells Rules ▸ Duplicate Values.
Choose a fill (e.g. Light Red Fill with Dark Red Text) and click OK.
To extend the check later, reselect a wider range and reapply, or edit the rule in Manage Rules.
What this does
Conditional Formatting colours repeated cells automatically, giving you an instant visual map of where duplicates sit — no formula and no helper column. The built-in Duplicate Values rule compares every cell in the selection and shades the ones that appear more than once. Because the rule is live, the colours update the moment you edit, paste or add data, so duplicates can never sneak back in unseen. Before you run it on a workbook other people depend on, try it on a copy or a few rows first. Undo only reaches back through the current session, so a quick trial run is the cheapest way to see exactly what will change before the file is saved and shared. Treat “highlight duplicate entries in excel” as a small repeatable workflow rather than a one-off click you hope to remember next time. Use a small test block before the live file, so any surprise in the affected duplicates shows up while it is still harmless. When this is a ribbon command, the selection matters more than the button: confirm the range, apply the command, then spot-check the output before saving. That turns a data step that keeps your analysis trustworthy into a method you can reuse, explain, and defend when the workbook leaves your screen.
A worked example
You have customer emails in B2:B20. Select that range, go to Home ▸ Conditional Formatting ▸ Highlight Cells Rules ▸ Duplicate Values, and choose the red fill. Every email that appears twice — say jo@acme.com sitting in B4 and B17 — turns red in both cells, while one-off addresses stay white. Type a new repeat and it reddens instantly. When you want to see duplicates at a glance during data entry or review — spotting a double-booked email or a repeated invoice number on screen — coloured cells beat any formula, because the eye catches them instantly and the rule keeps watching as you type. If this is something you do often, add the command to the Quick Access Toolbar (right-click it on the ribbon and choose Add to Quick Access Toolbar) or learn its shortcut, so next time it is one click instead of a hunt through the menus.
In Google Sheets
This is a command rather than a formula, so there is no syntax to carry over. Google Sheets arranges its commands in menus across the top instead of a ribbon, names some of them differently and does not have every Excel command — look for the equivalent in the Sheets menus or its help before assuming the steps match. Keep this page bookmarked for the next time the same question comes up. Better still, repeat the steps once in your own workbook — doing it yourself is what turns a copied answer into something you remember. Treat “highlight duplicate entries in excel” as a routine rather than a one-off. Once you know which setting or command controls it, the same few steps handle every workbook where it comes up in Excel, and you can explain them to a colleague in a sentence.
Common mistakes
- Selecting one column when duplicates should be judged across several — the rule only compares the cells you highlight.
- Expecting the colour to remove anything; highlighting is purely visual, deletion is a separate step.
- Leaving the selection too small, so duplicates outside the range never get coloured.
- Confusing "Duplicate Values" with "Unique" in the same dialog — the dropdown switches between colouring repeats and colouring one-offs.
Frequently asked questions
How do I highlight whole rows, not just cells?
Use a formula rule instead: New Rule ▸ Use a formula, enter =COUNTIF($B:$B,$B2)>1 and apply the fill to the whole row range.
Can I highlight duplicates in one colour and uniques in another?
Yes — add two rules: one Duplicate Values rule and one Unique Values rule, each with its own fill.
How do I clear the highlighting?
Home ▸ Conditional Formatting ▸ Clear Rules removes the colouring without touching your data.