How to Find All Outlook Emails Larger Than 25 MB With Size Operator

When your Outlook mailbox fills up, large email attachments are often the main cause. Outlook includes a search operator called size that lets you find messages above a specific file size. You can use this operator in the search box or build a search folder that updates automatically. This article shows you how to use the size operator to locate all emails larger than 25 MB and how to create a search folder for ongoing management.

The size operator works in Outlook for Microsoft 365, Outlook 2021, Outlook 2019, and Outlook for the web. It supports standard size units: bytes, KB, MB, and GB. You can combine the size operator with other search terms to narrow results by sender, date, or subject.

How the Size Search Operator Works in Outlook

The size operator is part of Outlook’s Instant Search system. It uses the Windows Search index to scan message properties, including the total size of each email and its attachments. The operator accepts comparison symbols: greater than (>), less than (<), equal to (=), greater than or equal to (>=), and less than or equal to (<=). You must place the operator directly after the colon with no spaces.

The unit can be bytes, KB, MB, or GB. Outlook treats the unit as case-insensitive, so MB and mb produce the same result. If you omit the unit, Outlook assumes bytes. For example, size:>26214400 (25 MB in bytes) returns the same results as size:>25 MB.

The search scans the currently selected folder by default. To search all mailboxes, click the All Mailboxes button or select All Outlook Items in the search scope dropdown before typing the operator.

Steps to Find Emails Larger Than 25 MB Using the Size Operator

Follow these steps to run a one-time search. This method works in Outlook desktop and Outlook for the web.

1. Open Outlook and click the search box
   The search box is located above the message list. In Outlook desktop, press Ctrl+E to jump directly to it. In Outlook for the web, the search box is at the top of the page.
2. Type the size operator
   Type size:>25 MB exactly. Do not add spaces after the colon. The search results update as you type.
3. Refine the search scope if needed
   By default, Outlook searches the current folder. To search all folders, click All Mailboxes in the search toolbar. In Outlook for the web, click All folders in the search dropdown.
4. Add additional search filters
   Combine the size operator with other keywords using AND. For example, type size:>25 MB AND from:contoso.com to find large emails from a specific domain. Use subject: to filter by subject line.
5. Review and take action on the results
   Right-click any message to delete, archive, or move it. To sort results by size, click the Size column header. If the Size column is not visible, right-click the column headers and select Size.

Using the Size Operator in Outlook for the Web

Outlook for the web supports the same size operator. In the search box, type size:>25 MB. The web version also supports size:>25 MB AND hasattachment:yes to find only messages with attachments. Note that Outlook for the web does not support search folders.

Create a Search Folder to Automatically Track Large Emails

A search folder is a virtual folder that displays all messages matching a search criteria. It updates in real time as new emails arrive. This is the best way to monitor large emails without running the search manually.

1. Open the Create New Search Folder dialog
   Press Ctrl+Shift+P. Alternatively, go to the Folder tab and click New Search Folder.
2. Select the Custom search folder option
   Scroll to the bottom of the list and click Create a custom Search Folder. Then click Choose.
3. Name the search folder
   Type a name such as Large Emails > 25 MB.
4. Define the search criteria
   Click Criteria. In the Search Folder Criteria dialog, go to the Advanced tab. Click Field > All Mail fields > Size. In the Condition dropdown, select greater than. In the Value box, type 25 MB. Click Add to List.
5. Save the search folder
   Click OK in each dialog. The new search folder appears under Search Folders in the folder pane. Click it to view all emails larger than 25 MB.

Common Issues When Using the Size Operator

Search returns no results even though I have large emails

This usually means the Windows Search index is not up to date. In Outlook desktop, go to File > Options > Search > Indexing Options. Click Advanced and then Rebuild. Rebuilding the index can take several hours for large mailboxes. After the rebuild completes, repeat the search.

The size operator does not work in Outlook for Mac

Outlook for Mac uses a different search syntax. The size operator is not supported. Instead, use the Organize tool or create a smart folder that filters by message size in bytes.

Size search includes only the message body, not attachments

Outlook calculates the size of an email as the total of the message body plus all attachments. The size operator returns the combined size. If you need to find only messages with large attachments, use size:>25 MB AND hasattachment:yes.

Item	Search Folder	Instant Search
Description	Virtual folder that updates automatically	One-time search in the search box
Setup time	Requires 5 steps to create	Instant, just type the operator
Persistence	Permanent until deleted	Results disappear when you clear the search
Best for	Ongoing monitoring of large emails	Quick checks or one-time cleanup
Available in Outlook for the web	No	Yes

Now you can find all Outlook emails larger than 25 MB using the size operator in the search box or by creating a search folder. Use the search folder if you need to regularly check for large messages. For a one-time cleanup, the instant search with size:>25 MB works faster. To locate emails with the largest attachments first, sort the results by the Size column after the search completes.