HubSpot conversion events and Google Ads

[OBudai]

Hello Community,

I’m experiencing an issue with configuring the integration between HubSpot conversion events and Google Ads.

I’ve created events such as HubSpot – Lead, HubSpot – Marketing Qualified Lead, etc. However, on the Google Ads side, I sometimes see only 1-2 conversions, which is significantly lower than the numbers shown in HubSpot. Additionally, I don’t see any “Last sync” status in HubSpot for these events.

Has anyone encountered a similar issue? What could be the possible reasons for this discrepancy?

I’d really appreciate your thoughts and suggestions.

[danmoyle · Accepted solution]

Welcome to the Community @OBudai! It's a tale as old as time, it seems.  I've heard this since I started using HubSpot back in 2010. Two different systems rarely sync perfectly. Here's what's going on. Different attribution models lead to mismatches. HubSpot counts net-new contacts via its tracking cookie and UTMs, while Google Ads attributes based on click/view-through windows and may count repeat events per user. No GCLID (Google Click ID) captured on contacts, lack of hashed customer data sharing (e.g., email/phone), or using a Google Ads Manager/MCC account prevents syncing for enhanced conversions. Delays in sync (up to 48 hours for enhanced conversions activation), ad blockers, cross-domain issues, or time zone differences can reduce counts in Google Ads.
​

Here are a few troubleshooting steps you could take. 

1. Navigate to Marketing > Ads > Events in HubSpot; verify events are toggled on, review details, and check for "Update to EC" prompts to enable Enhanced Conversions for Leads.
2. In Google Ads, go to Tools & Settings > Conversions; ensure enhanced conversions is on (API method), and confirm events appear as conversion actions with "Included in conversions" set to Yes.
3. Re-authenticate the integration: Settings > Marketing > Ads > Troubleshoot > Re-sync, using a Google user with full admin rights.
4. Confirm contacts have GCLID property populated and consent/data sharing enabled in event settings; test with a recent lifecycle change.

​I looked up some best practices to hopefully prevent this as best you can, and here's what I found. Use "All contacts that move to the selected lifecycle stage(s)" for syncing to maximize ad optimization data, and monitor for UTM consistency via HubSpot's auto-tracking. Note that exact 1:1 matches aren't expected due to platform differences. HubSpot lacks sync logs without errors. For persistent issues, share a non-syncing contact example in HubSpot Community for deeper review.

Hopefully this helps! 

[OBudai]

Hi Dan, @danmoyle 

Thank you very much for your detailed response. I can now see the last sync date, however, the discrepancy between the two tools is quite significant. Could you please share the level of difference you experienced on your side, just for comparison?
Thanks,
Alyona

[BérangèreL]

Hi @OBudai and thanks so much for reaching out and sharing your question with the HubSpot Community.
 

It’s not uncommon to notice discrepancies between HubSpot and Google Ads conversion numbers. This can sometimes be due to differences in how each platform tracks and attributes conversions, or delays in syncing the data.

If you’re not seeing a “Last sync” status for your events, it might be worth double-checking the integration settings or re-authenticating the connection.
 

I’m tagging some of our experts to see if anyone has tips or solutions to share. Hi @danmoyle, @Lucila-Andimol and @TomM2 do you have suggestions to help @OBudai, please?

Thanks so much in advance for your valuable contributions and have a lovely day!
Bérangère