LinkedIn Ads Manager

Three or four fields is the documented sweet spot^[1]. The form template supports up to 12 fields, but every field you add beyond four typically costs you 10 to 20% on submission rate^[2]. Top performers land between 12 and 15% form conversion in 2026; the 8 to 11% average pulls in everyone who left the defaults at six or seven^[3].

Stick to fields LinkedIn auto-fills from the member's profile: first name, last name, work email, job title, company name^[1]. Avoid phone number, gender, and free-response custom questions - each free-response field drops submission rate another 3 to 4 points^[2]. If you need lead qualification, do it after the form fires by enriching against your CRM, not by adding form fields.

For API-driven campaigns, set objectiveType: LEAD_GENERATION on the campaign and keep offsiteDeliveryEnabled: False^[4]. Leads are then retrievable via the lead sync API with leadType: SPONSORED^[5]. For accurate optimization, pair the form with a server-side QUALIFIED_LEAD conversion via the Conversions API so the bidder learns from MQL signal, not raw form submits^[6].

Cortex Lead Form Sentry flags any active LEAD_GENERATION campaign with more than four required fields, more than zero free-response custom questions, or a non-profile field like phone number - and proposes the trimmed version with projected lift before publishing.