How to remove duplicate contacts in Outlook and Microsoft 365

New Outlook and Outlook on the web hide exact duplicate contacts. The hidden contacts are still in your mailbox.

Classic Outlook does not remove duplicates for you. Microsoft's steps are to delete them one by one, or to export your contacts and import them again.

Below are both of Microsoft's ways, step by step. They start with a backup and end with what Outlook can't do.

How Outlook handles duplicate contacts

New Outlook and Outlook on the web:

• They hide exact duplicates. They also hide a contact that holds a subset of another contact's fields.
• This runs in the background. You do nothing.
• The hidden contacts stay in your mailbox. You can still see them in classic Outlook, Outlook for Mac and Outlook mobile.

Classic Outlook:

• It does not hide or remove duplicates for you.
• When you save a contact that already exists, it asks whether to add a new contact or update the existing one.
• To remove duplicates, Microsoft gives two manual ways. The steps are below.

How to remove duplicate contacts in classic Outlook

Export a backup first. The second way moves every contact you have, so keep a copy. In classic Outlook, go to File > Open & Export > Import/Export. Choose Export to a File, then Comma Separated Values, and pick your Contacts folder. In Outlook on the web, go to People > Manage contacts > Export contacts.

These are Microsoft's steps. Both work inside one account.

Delete them one at a time:

1. Open People.
2. On the Home tab, under Current View, choose Phone. This view makes duplicates easier to spot.
3. Hold Ctrl and click each duplicate.
4. Press Delete.

Export your contacts and import them again:

1. Open People. Right-click your Contacts folder and choose New Folder. Name it "Duplicates".
2. Open your Contacts folder. Press Ctrl+A and move every contact into the Duplicates folder. Your Contacts folder is now empty.
3. Go to File > Open & Export > Import/Export. Choose Export to a File, then Comma Separated Values (Windows).
4. Choose the Duplicates folder and save the file. Click Finish.
5. Go to File > Open & Export > Import/Export again. Choose Import from another program or file, then Comma Separated Values (Windows), and pick the file.
6. Choose Do not import duplicate items. Choose your empty Contacts folder as the destination. Click Finish.
7. Open the Duplicates folder. Press Ctrl+A and move every contact back into your Contacts folder.
8. Outlook asks about each duplicate. Choose Update information of selected contact, or Add new contact if it is a different person. Click Update or Update All.
9. Delete the Duplicates folder.

Where Outlook stops

Hidden is not removed. The duplicates stay in your mailbox. If you delete the visible contact in new Outlook, the hidden copies are deleted too.

Only exact copies. Microsoft says it hides exact copies and contacts that hold a subset of another contact's fields. Two contacts with different names stay visible.

One account at a time. Outlook's hiding works inside one account. The same person in Outlook and in Google is not found. To merge them, read how to merge contacts across accounts.

Classic Outlook takes manual work. You delete duplicates one at a time. Or you export all your contacts and import them again.

Remove Outlook duplicates with ContactZapp

Take Sarah Chen. Your Microsoft account has her twice, as an exact copy. New Outlook hides one of them. Classic Outlook and Outlook mobile show both. Your Google account has her as "S. Chen", with her personal email and the same phone number.

ContactZapp finds duplicates within one account and across accounts. It puts all 3 contacts in one group. You merge once, with no export and no import. The merged contact keeps both email addresses. It is sent to Outlook and Google. You can undo the merge for 12 months.

See how merging across accounts works, or the questions about merging.

FAQ

Does new Outlook remove duplicate contacts? No. New Outlook and Outlook on the web hide exact duplicates. The hidden contacts stay in your mailbox. If you delete the visible contact, the hidden copies are deleted too.

Why do I still see duplicates in classic Outlook or Outlook mobile? The hiding happens only in new Outlook and Outlook on the web. Classic Outlook, Outlook for Mac and Outlook mobile still show every copy.

Does Outlook find duplicates with different names? No. Microsoft says it hides exact copies and contacts that hold a subset of another contact's fields. "Sarah Chen" and "S. Chen" both stay.

Can I merge duplicates from 2 Outlook accounts? Not in Outlook. Its duplicate handling works inside one account. Each account keeps its own copy of the person.

Does ContactZapp work with classic Outlook? Yes. It connects to your Microsoft account, personal or work, including Microsoft 365. Classic Outlook shows the merged contact after its next sync.