By Prakhar KirsaliPublished Topic: GA4
Short answer
Mark an event as a GA4 key event only if it represents a business outcome you would pay for: a completed lead form, a booked call, a purchase, a qualified phone call. Scrolls, page views, and form starts are useful diagnostics but should stay ordinary events. Import into Google Ads only the one or two outcomes you want bidding to optimise toward.
In 2024 Google renamed GA4 "conversions" to "key events", and kept the word "conversion" for what Google Ads actually bids on. The rename is useful: a key event is something important to you in analytics, a conversion is something you are telling an ad platform to buy more of. They should not be the same long list.
A practical rule for choosing key events
Ask: if this event doubled tomorrow and nothing else changed, would revenue go up? A completed enquiry form — yes. A visit to the contact page — no. Only the first belongs in key events.
| Event | Key event? | Import to Google Ads? |
|---|---|---|
| generate_lead (form submitted, thank-you confirmed) | Yes | Yes — primary |
| booked_call (calendar booking confirmed) | Yes | Yes — primary or secondary |
| phone_call_click | Yes, if calls matter | Secondary (observation only) |
| form_start | No | No |
| scroll / page_view / file_download | No | No |
The double-counting trap
A common setup fires generate_lead from Google Tag Manager on form submit and also creates a GA4 "create event" rule from the thank-you page view. Each lead is now counted twice. Check in DebugView: submit one test lead and confirm exactly one generate_lead appears.
The same issue appears between platforms: importing a GA4 key event into Google Ads while a Google Ads conversion tag also fires for the same action. Pick one source per action and set the other to secondary.
Counting method: once per event or once per session
GA4 lets you choose per key event. For leads, "once per session" stops a visitor who refreshes the thank-you page from being counted three times. For purchases, count every event, since each is real revenue.
Getting key events into Google Ads
Link GA4 and Google Ads, then import the chosen key event as a conversion action. Set it as primary only if you want Smart Bidding to optimise toward it. Imported GA4 conversions use GA4's attribution and can lag; for the main lead action many accounts use a native Google Ads tag with enhanced conversions instead, and keep the GA4 import as secondary.
Validate before you trust it
Compare a week of key events with the leads that actually arrived in your inbox or CRM. If GA4 shows 60 leads and the CRM shows 41, find the gap before changing any budget. This reconciliation step is the core of GA4 and analytics setup.
Frequently asked questions
- What is the difference between a GA4 key event and a Google Ads conversion?
- A key event is an important action in GA4 reporting. A Google Ads conversion is an action Google Ads counts and, if primary, bids toward. You can import key events as conversions, but you do not have to import all of them.
- How many key events should a lead-generation site have?
- Usually two to four: the main lead form, booked calls, qualified phone calls, and possibly a high-intent action like a quote request. Fewer, more meaningful events give clearer reports.
- Should I mark form_start as a key event?
- No. Form starts are a useful diagnostic for form drop-off, but they are not an outcome. Marking them inflates conversion rates and can mislead bidding if imported.