How does HubSpot attribute deals to ads?

Calculating ROI with HubSpot's Manage Ads Feature

Quoting HubSpot's help article:

  • Deals: the number of Closed Won deals associated with the attributed contacts in the Total Contacts column. Since the Total Contacts amount will vary depending on the selected attribution report, this metric will also vary based on attribution report. The below must be true to be attributed to an ad:
    • The deal stage is Closed won.
    • The deal is associated with a contact.
    • The Close date property is populated.
    • The associated contact Lifecycle stage is Customer
    • The associated contact is attributed to an ad on the Ads dashboard.
    • The correct date range is selected. The date range is based on the deal's Closed Won date.

Source: Analyze ad campaigns in HubSpot (HubSpot Knowledge Base)