Categories are Outlook's main tool for color-coding your calendar. Each category is a named color you can apply to events, emails, and tasks—so "Travel" might be blue and "Focus time" green across everything. This guide explains how categories work, how to create and rename them, and how they differ from the color assigned to an entire calendar.
Categories vs. calendar colors
These are two separate systems, and mixing them up causes confusion.
| Categories | Calendar color | |
|---|---|---|
| Applies to | Individual events (and email/tasks) | An entire calendar |
| Has a name | Yes (e.g., "Travel") | No—just a color |
| Shared across Outlook | Yes, across mail and calendar | No |
| Multiple per event | Yes | One per calendar |
Use categories to label types of events; use calendar color to tell whole calendars apart (for example, Work vs. Personal). To recolor an event or a calendar, see How to Change Event Colors in Outlook.
Create and manage categories
New Outlook for Windows and Outlook on the web
New Outlook and Outlook on the web (outlook.office.com or outlook.com) share the same category list.
- Open any event, or right-click an event on the grid and choose Categorize.
- Select Manage categories (or New category).
- Enter a name and pick a color.
- Save. The new category is now available everywhere in that account.
To rename or recolor:
- Open Categorize → Manage categories.
- Select the category, change its name or color, and save. Existing events using it update automatically.
Classic Outlook desktop
- On the Home ribbon, select Categorize → All Categories.
- In the Color Categories dialog, choose New to create one, or select an existing category and use Rename or the color dropdown.
- You can also assign a keyboard shortcut here.
- Select OK.
Apply a category to an event
- New Outlook / web: right-click the event → Categorize → pick a category. Or open the event and use the Categorize option.
- Classic desktop: right-click the event → Categorize, or open it and select Categorize on the ribbon.
You can apply more than one category to a single event. In that case Outlook shows the event with the most recently applied color and lists the others on the event details.
Mobile
The Outlook mobile app shows category colors that already exist, and on newer versions you can apply an existing category to an event by opening it and choosing Categorize. Creating and renaming categories is best done on desktop or the web, since mobile management is limited.
Tips for a usable color system
- Keep it small. Six to eight categories you actually recognize beat twenty you can't remember.
- Name by type, not project. "Deep work," "External," and "Personal" age better than one-off project names.
- Reuse across mail and calendar. Because categories are shared, the same colors help you triage your inbox too.
- Watch shared calendars. When you view someone else's calendar, you see their categories' colors but manage your own list separately.
Why categories don't always sync everywhere
Categories live with your mailbox, so they sync across new Outlook and the web for the same account. Classic Outlook keeps its own master category list that should sync for Exchange/Microsoft 365 accounts but can occasionally fall out of step—if a color looks wrong, reopen the Manage categories list and confirm the name and color match.
Color-coding is most useful when every calendar lives in one place. nocal brings your Outlook and Google calendars into one timeline — see how.
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