GA4 and Google Ads conversions don't match? Why, and which change widened the gap

Why don't GA4 and Google Ads conversions match?

Because they answer different questions. Google Ads asks which ad interaction led to a conversion and reports it on the date of that click. GA4 asks what happened on your site and reports the conversion on the day it occurred, with credit spread across the channels it can see.

Google's help page on creating conversions from Google Analytics events gives a simple case: someone clicks an ad on July 19 and buys on July 20. Google Ads records the conversion on July 19; Analytics records it on July 20. Over a week the totals can come close, but day by day they rarely line up.

Default attribution scope adds a second gap. According to Google's attribution settings help, Google Ads reports default to Google paid attribution, while Google Analytics reports default to paid and organic channels. A buyer who clicked a Search ad and later came back from an organic result can be a full conversion in Google Ads and only a partial one for the Google Ads rows in GA4.

So the useful question is not why they don't match, but whether the gap has changed. A gap that stays near the same ratio for months is the cost of running two measurement systems. A gap that jumps on a specific day almost always has a cause you can date.

What are the main reasons the numbers differ?

Most of the difference comes from seven settings and behaviours. Check them in this order, because the first three explain most everyday gaps.

Two facts trip up even experienced teams. First, an import does not bring history: Google says imports don't include data from before the import, so the first weeks after switching to a GA4-imported action are not comparable with what came before. Second, conversion actions created from the Google Analytics interface are set as Secondary by default, so they appear in "All conversions" but not in "Conversions" until someone changes them in Google Ads.

Also compare the same column every time. "Conversions" includes only primary actions; "All conversions" also includes secondary actions, view-through conversions and other sources. Comparing GA4 key events with "All conversions" one day and "Conversions" the next invents a gap that isn't there.

Which settings changes make the gap wider?

A gap that changes overnight is usually a configuration edit in one of the two tools, not a change in buyer behaviour. These are the edits to look for first.

• A second primary action for the same event. Importing a GA4 key event as primary while the Google tag action for the same purchase or lead is still primary makes Google Ads count it twice. The post on duplicate conversions in Google Ads shows how to confirm it.
• Counting method switched. Moving a lead action from "One" to "Every" raises Google Ads counts for anyone who converts twice. Google's own example: two form fills in separate sessions after one click are 2 key events in Analytics, 1 conversion with "One" and possibly 2 with "Every".
• GA4 reporting attribution model changed. This change applies to historical and future data, so last month's GA4 numbers can change after the fact while Google Ads stays the same.
• Lookback window or channels setting changed. Both apply only going forward. The channels setting also applies to all linked Google Ads accounts and can take a few days to show, which makes it easy to miss when the gap moves.
• Time zone edited in the GA4 property or in the Google Ads account.
• Key event renamed or recreated. Renamed key events can take up to 24 hours to show up in Google Ads, and a recreated event may no longer feed the imported action.
• Tag or consent changes. A new landing page template without the Google tag, a redirect that strips the click ID, or a new consent banner. Google's conversion discrepancy guide points to the "Tag coverage" summary in Google Ads to find untagged landing pages. For banners, see how to prove a consent banner caused a drop.

Only some of these live in Google Ads. GA4 property settings, tag releases and consent banners are changed somewhere else, often by someone else, and that is why the gap so often looks unexplained.

How do I check whether the gap is normal?

Compare like with like first, then look at the gap over time instead of on a single day.

1. Pick one real event, for example purchases, and compare one GA4 key event with the one Google Ads conversion action built from it, never a total of all actions.
2. Use the "Conversions" column and check which actions are primary under Goals > Summary.
3. Compare weeks rather than days, so click-date and conversion-date differences mostly cancel out, and leave out the last 24 hours to allow for import delays.
4. In GA4, look only at the Google Ads campaign rows; in Google Ads, remember the default is Google paid attribution.
5. Confirm that the GA4 property and the Google Ads account use the same time zone.
6. Add your source of truth, the store backend or the CRM, as a third column. If GA4 and the backend agree and Google Ads is the outlier, start in Google Ads, and the other way round.
7. Chart the ratio of Google Ads conversions to GA4 key events by day for the last 90 days. A flat line is your normal gap. A step is a change.

The Google Ads change history covers changes from the past 2 years, but Google's change history help notes that not all account-level settings changes may be listed, and it shows nothing that happened in GA4, your tag manager or your website.

How do I isolate which change widened the gap?

Find the day the ratio stepped, then put every change from the days before it on one timeline: edits to conversion actions in Google Ads, GA4 admin changes, tag and website releases, consent banner updates and platform automations.

1. Compare like with like
2. Chart the gap ratio by day
3. Line up every change
4. Test one hypothesis

Rule out broken tracking before anything else, then test one hypothesis at a time: correct one setting, wait at least one full conversion cycle and check whether the ratio returns to its old level. Changing three settings at once may fix the numbers without telling you which one was wrong.

With every change on one timeline, the cause usually stands out: you would see that a GA4 key event was imported as a primary action the day before the ratio jumped, while the old tag action was never moved to secondary. In Changeline, Google Ads edits are imported automatically, and the team logs GA4, tag and site changes on the same timeline with date, owner and reason, so "what changed on Tuesday?" has one place to look.

Example: a client asks why Google Ads shows 62 leads last week while GA4 shows 41. For months the ratio had sat around 1.1. Charting it by day showed a step on Wednesday. Lining up the changes from Monday to Wednesday showed a GA4 lead event imported as a primary action on Tuesday afternoon, while the Google tag form action stayed primary. Setting the old action to secondary brought the ratio back to about 1.1 the following week. Names and numbers are illustrative.

How do I keep GA4 and Google Ads aligned?

You won't make them identical, but you can keep the gap stable and explained.

• Decide which tool answers which question: Google Ads for bidding and campaign optimisation, GA4 for behaviour across channels, the backend or CRM for revenue and lead totals.
• Keep one primary action per real event. Everything else stays secondary.
• Write down the current settings: counting method, conversion windows, GA4 attribution model, lookback windows, channels setting and both time zones.
• Treat every edit to those settings as a change with a date, an owner and a reason, and mark it in GA4 as well; the guide to GA4 annotations shows how.
• Recheck the gap ratio every month and after every tracking release.

When a client sees two different numbers, explain the expected gap before they ask. If the gap does change, the method in the guide on explaining a conversion drop to a client works the same way: show the date, the change and the evidence.