Convert a Lead into a current Contact or Opportunity

Associate a converted Lead to an existing Contact in Salesforce Classic or Lightning Experience

To select an existing Contact record during the lead conversion process has two requirements:

• You can create an account or choose an existing account.
• There must be an existing Contact to de-dupe against.

If you don't have access to the two requirements above, you can't see the "Attach to Existing Contact" screen.
 
If your user meets the above requirements, follow the steps below to convert the Lead: 
 

Classic Instructions:

1. Click the Lead tab.
2. Open the Lead record that needs to be converted and click Convert.
3. In the Account Name field, select Attach to Existing Account (for example: "Big cars Account").
4. Complete the other details on the page as per the requirement and click Convert.
5. Since a Contact with the same name already exists in the selected Account, it allows you to either create a new Contact or Attach to an existing contact.
6. Select the Contact in which you want to merge the Lead while converting.
7. Click Convert.

Lightning Experience Instructions:

1. Navigate to the Lead record
2. Click Convert on the upper right part of the page
3. Convert to Existing Account
4. Then choose to convert to the existing contact if there is a duplicate detected
5. Select the existing contact record you want the lead to be converted to
6. Update Lead Source of the existing contact (Optional)
7. Select a record owner and converted status and click Convert

Notes:

• As Opportunity is a required field, but if you don't want to convert the lead into opportunity, select the 'Don't create an opportunity upon conversion' checkbox.  
  Note : On lead conversion, Opportunity must have a default record type, even though we have selected the option 'Don't create an opportunity upon conversion', otherwise user will not be able to convert the lead and will get the error 'Unable to find default record type'.
• If the Convert button is not displayed, check the page layout of the object. The Convert button is Mobile & LIghtning Action and needs to be placed under the Salesforce Mobile and Lightning Experience Actions section. If the layout does not include this action, the Convert button won't be displayed. 
• The same applies when converting a Lead into an existing Opportunity. You can only convert a Lead to an existing Opportunity if the Account is already available and when you choose an existing Account, you can then select existing Opportunities related to the Account.
• Only 20 matching Opportunities can be shown when converting and selecting the option "existing Opportunities."