# GA4 key events, conversions and what Google Ads imports

> A key event belongs to GA4; a conversion is what Google Ads uses to measure and bid. See the difference, the counting and how to import without double counting.

- URL: https://relator.digital/en/blog/ga4-conversoes-vs-eventos-chave
- Publicado: 2026-10-09
- Atualizado: 2026-10-09
- Autor: Time Relator Digital
- Categoria: marketing-data

In GA4, a key event is any event you mark as important to your business. A conversion is an action that Google Ads uses to measure campaign performance and guide bidding. The same action can be both, but each has its own count and its own settings, and that is where the numbers stop matching.

> [!NOTE]
> **In short**
> - A key event is a Google Analytics concept; a conversion is a Google Ads concept. In the Portuguese Analytics interface, the key event is called "evento principal".
> - Any collected event can be marked as a key event.
> - GA4 counts a key event "once per event" (recommended) or "once per session" (legacy). Changing the counting method only applies going forward.
> - Conversions imported from GA4 arrive in Google Ads as secondary: they show in "All conversions" and do not feed bidding until you change that in Google Ads.
> - Before importing, decide which source owns each action so you do not measure the same thing twice.

## A key event is not a conversion

For years GA4 used the word "conversion" for the important actions on a site. Today the documentation separates the two concepts. A key event measures an action that is particularly important to the success of the business and shows up in Analytics reports. A conversion, according to Google, is an important action you want to use to measure the performance of your ad campaigns. It is created in Google Ads based on an Analytics event.

In practice, the question that tells them apart is: **what is this number for?**

- To understand how visitors behave (scrolled the page, opened the quote form, clicked WhatsApp)? It is a key event and stays in Analytics.
- To evaluate paid campaigns and guide bidding strategy? It is a conversion and lives in Google Ads.

One useful detail: an event that is not a key event can also generate a conversion. In that case GA4 automatically marks it as a key event. So creating the conversion in Google Ads from an Analytics event does not leave the event "outside" GA4.

![From event to bid: three steps, with what happens at each](https://uploads.relator.digital/blog/ga4-conversoes-vs-eventos-chave/7ee54bdf-fluxo.en.svg "From the collected event to the conversion that feeds bidding")

## Marking a key event is the first step

The path is short. You identify or create the event, open the key events page in the property's admin area and mark it. Any collected event can be marked. Google's own example is the scroll event (`scroll`) on a lead generation page, marked to evaluate user behavior.

Two precautions avoid a confusing report:

1. **Few and clear.** Mark the actions that represent the business goal (form submission, purchase, click to chat on WhatsApp). One key event per micro-interaction turns the list into noise.
2. **An agreed name.** Define the event name with whoever implements the tag before marking it, so the report and the metrics dictionary always use the same one.

## How GA4 counts: per event or per session

GA4 offers two counting methods for a key event:

- **Once per event** (recommended): counts a key event every time it fires.
- **Once per session** (legacy): counts a key event only once within a given session.

The default depends on origin. Key events created from Universal Analytics goals, in automatically created properties or through the goals migration tool after April 2023, use "once per session". All the others use "once per event". And there is an important warning: changing the method only applies to future events and does not change past data.

A hypothetical example shows the size of the difference. A site gets five sessions in which the form submission event fires like this:

| Session | Event firings | Count per event | Count per session |
| --- | --- | --- | --- |
| 1 | 1 | 1 | 1 |
| 2 | 3 | 3 | 1 |
| 3 | 1 | 1 | 1 |
| 4 | 2 | 2 | 1 |
| 5 | 1 | 1 | 1 |
| **Total** | **8** | **8** | **5** |

The math: 1 + 3 + 1 + 2 + 1 = 8 firings; with per-session counting each of the 5 sessions counts once, so 5. Per-event counting comes out 60% higher (8 ÷ 5 = 1.6). If someone compares today's report with one from before the method changed, part of the variation comes only from the counting rule, not from audience behavior.

## What happens when you import into Google Ads

To import a key event from GA4 as a Google Ads conversion, Analytics and Google Ads must be linked, auto-tagging must be on, and you need at least Marketer access on the property. The documentation also lists being an administrator or editor.

After the import, three rules drive the outcome:

1. **The conversion is born secondary.** Google marks conversions based on key events, or created through the Analytics interface, as secondary precisely to avoid counting the same event twice for bidding. You only see that number in "All conversions".
2. **Google Ads decides the bidding.** Goal category and action optimization cannot be edited from Analytics; only in Google Ads. For the conversion to feed bidding, you change it to primary in the action optimization section.
3. **Primary and secondary go to different places.** Primary actions show in the "Conversions" column and are used for bidding. Secondary actions go to "All conversions" and are for observation, without feeding bidding (custom goals are the exception, using both types).

The value travels too: each key event's value is measured in the GA4 property and imported automatically into Google Ads.

## Google Ads counting is a separate setting

Google Ads has its own counting option for each conversion action. "Every" counts each conversion that happens after an ad interaction and is suited to sales. "One" counts only one conversion per ad click and suits leads, when you want to know whether a kind of lead was generated, not how many times.

So the same person can generate more than one count in GA4 and only one in Google Ads, depending on the methods chosen on each side. Before complaining about a discrepancy, compare the two settings. A starting point (ours, not a Google rule): leads with "One" in Google Ads, sales with "Every".

## Import from GA4 or use the Google Ads tag?

Google's documentation describes how to import but does not decide for you. These are working criteria, suggested by us:

- **Import from GA4** when you want a single definition of "lead" and "sale" across the Analytics report and Google Ads, or when the event's value is already measured in the property.
- **Use the Google Ads tag** when the conversion only makes sense in the ad platform and you do not want to depend on what is marked in GA4.
- **Never leave both as primary for the same action.** Hypothetical example: if 40 real leads were measured by the tag and also by the imported event, and both actions were primary, the "Conversions" column would show 80 (2 × 40). Google's design, with the import being born secondary, exists to avoid exactly this mistake.

## Where Relator fits

Relator connects Google Ads and GA4 in the same workspace, so the ad conversion number and the site event number sit side by side in the client report. Deciding which event is the main conversion is still up to you, and it should be written in your metrics dictionary.

## How to apply

1. List the actions that matter to the client (lead, sale, contact) and give each event a fixed name.
2. Mark as key events in GA4 only the actions on the list.
3. Check the counting method of each one: "once per event" is the recommended one; record the date of any change.
4. For each action, decide the conversion source: imported from GA4 or Google Ads tag. Write the decision down.
5. Link GA4 to Google Ads, turn on auto-tagging and import the chosen actions.
6. In Google Ads, set as primary only the conversions that should feed bidding; leave the rest as secondary.
7. Set the counting in Google Ads: "One" for leads, "Every" for sales.
8. In the monthly report, state which column you are reading ("Conversions" or "All conversions") so nobody compares two different columns.

## Sources

All checked on October 9, 2026. Left out because we could not confirm them in an official source: the limit of key events per property and the delay between import and data appearing.

- Google Analytics, [Conversions vs. key events](https://support.google.com/analytics/answer/13965727): definitions, the difference between the two and creating the conversion from an event.
- Google Analytics, [Change the counting method of key events](https://support.google.com/analytics/answer/13366706): methods, defaults and effect on future events only.
- Google Analytics, [Create Google Ads conversions based on Google Analytics key events](https://support.google.com/analytics/answer/10632359): requirements and secondary conversions by default.
- Google Ads, [About primary and secondary conversion actions](https://support.google.com/google-ads/answer/11461796): columns and use in bidding.
- Google Ads, [Measure web key events from Google Analytics properties](https://support.google.com/google-ads/answer/9520128): import, value and optimization.
- Google Ads, [Conversion counting settings](https://support.google.com/google-ads/answer/3438531): "Every" versus "One".