Excel's default colors and where to change them

Excel does not have a single "default color" setting that applies to every new spreadsheet you open. Instead, Excel uses a theme — a set of colors, fonts, and effects that comes built in. The most common theme is called Office, which uses a white background with blue accents. You can change this theme for individual spreadsheets, or you can change the process-wide color mode (light, dark, or auto) that affects how Excel itself looks.

The confusion on Reddit often comes from people mixing up three different things: the theme colors used inside a spreadsheet, the dark mode or light mode of the Excel process itself, and the default template that opens when you create a new file. Each one is controlled in a different place.

Key Takeaways

  • Changing the theme colors inside a spreadsheet is done through the Page Layout tab, and affects only that file unless you save it as a template.
  • Changing Excel's process appearance (dark mode or light mode) is done in File > Options > General, and affects all your spreadsheets.
  • If you want every new spreadsheet to open with custom colors, you must create a template file and set it as your default.
  • Reddit threads about this often conflate spreadsheet themes with process appearance because the terminology is similar but the controls are separate.

How to change theme colors in a single spreadsheet

Open the spreadsheet you want to change. Go to the Page Layout tab (or Design tab in some versions). Look for the Themes group on the left side of the ribbon. Click the dropdown arrow under "Themes" to see the built-in options: Office, Office 2007-2019, Grayscale, Blue Warm, Blue Cool, and others.

Each theme changes the accent colors throughout your spreadsheet — the colors used in charts, cell fills, and formatted text. Click any theme to explore it when ready. This change affects only the current file. If you close the file without saving, the theme reverts to what it was before.

If you want to fine-tune individual colors within a theme, stay on the Page Layout tab and look for Colors (a separate dropdown from Themes). This lets you swap out just the color palette while keeping the same theme structure. For example, you can use the Office theme but with the "Blue II" color set instead of the default blue.

How to change Excel's dark mode or light mode

The appearance of Excel itself — whether the ribbon, menus, and background are light or dark — is separate from the spreadsheet theme. To change this, click File in the top left, then Options at the bottom of the left sidebar. In the Options window, click General on the left.

Look for the section labeled Personalize your copy of Microsoft Office. You will see a dropdown for Office Theme with three choices: Colorful (light background), Dark Gray (dark background), or Black (very dark background). Select the one you prefer and click OK. This change takes effect when ready and applies to all your spreadsheets and other Office programs.

Some people on Reddit report that their Excel opened in dark mode without them changing it. This usually happens because Windows itself is set to dark mode, and Excel is set to "Use system setting" or "Auto". If you want Excel to stay in light mode regardless of your Windows setting, choose Colorful explicitly.

How to set a custom default template for new spreadsheets

If you want every new spreadsheet to open with specific colors, fonts, or formatting, you need to create a template and tell Excel to use it as the default. Start by creating a spreadsheet with the exact look you want — colors, fonts, column widths, frozen panes, whatever you prefer.

Once it looks right, go to File > Save As. In the "Save as type" dropdown, select Excel Template (.xltx) instead of the normal spreadsheet format. Name it Book.xltx (this exact name is important). When prompted for a location, save it to your XLSTART folder. The path is usually C:\Users\[YourUsername]\AppData\Roaming\Microsoft\Excel\XLSTART on Windows.

After you save it there, close Excel completely and reopen it. When you create a new blank spreadsheet, it will now use your custom template instead of the standard one. If you ever want to go back to the default, delete Book.xltx from the XLSTART folder.

Why Reddit threads about this are confusing

People ask about "default colors" on Reddit because the terminology is scattered across different menus. Some answers point to themes (Page Layout tab), others point to dark mode (File > Options), and others point to templates (Save As). All three are correct answers to slightly different questions, which is why the same question gets multiple contradictory replies.

Additionally, Excel's interface changed between versions. Older versions used a "Design" tab instead of "Page Layout," and some versions have the theme controls in different places. A solution that works in Excel 2019 might not work the same way in Excel 365 or Excel for Mac. When you see a Reddit thread, check the comments for people mentioning their Excel version — that usually clarifies which answer applies to you.

What happens when you change colors in a shared workbook

If you are working on a spreadsheet that is shared with others through OneDrive or SharePoint, changing the theme affects only your view of the file. Other people will see the spreadsheet in whatever theme they have set, or in the default theme if they have not changed it. The theme is not stored as part of the file data — it is a personal preference setting.

If you want everyone to see the same colors, you need to change the actual cell fill colors and font colors manually, rather than relying on the theme. This ensures that when someone else opens the file, they see exactly what you see, regardless of their theme setting.

Frequently Asked Questions

Can I change the default color for just cell backgrounds, not the whole theme?

Yes. Select the cells you want to change, then use the Fill Color button on the Home tab to pick a specific color. This color stays with those cells no matter what theme anyone else applies. If you want this to be your default for future spreadsheets, create a template with those cells already filled, then save it as Book.xltx in your XLSTART folder.

Why does my Excel look different from my coworker's even though we have the same version?

You likely have different Office themes selected. Go to File > Options > General and check your Office Theme setting. Your coworker may have chosen Dark Gray while you have Colorful, or vice versa. You can also have different spreadsheet themes applied to individual files.

Does changing the theme affect the actual data or formulas in my spreadsheet?

No. Themes only change colors and fonts. Your data, formulas, and calculations remain exactly the same. You can switch between themes as many times as you want without affecting anything underneath.

What if I save a spreadsheet with a custom theme — will it keep that theme when someone else opens it?

The theme information is saved with the file, so yes, the other person will see the same theme when they open it. However, they can change it to a different theme on their end without affecting your copy of the file.

Can I create my own custom theme instead of using the built-in ones?

Not directly in the standard Excel interface. However, you can manually set cell colors, font colors, and formatting to create a custom look, then save that spreadsheet as a template. This achieves the same result as a custom theme for your own use.