Analytics · No. 22
Conversion and conversion value monitoring
In short
Conversions are visitor actions that matter to your business: a purchase, a lead, a call. In GA4 they’re called key events, and their value is passed in the value and currency parameters. Monitoring conversions by month and channel shows how much money each traffic source brings in, and warns you when tracking breaks after website changes.
Contents
What are conversions and key events in GA4?
A conversion is the action your website exists for: a purchase, a lead, a sign-up, a call. In Google Analytics 4 (GA4), every action is recorded as an event, and the property owner marks the events that matter to the business as special. Google calls them key events:
“A key event is an event that measures an action that’s particularly important to the success of your business.”
Google now reserves the word “conversion” for advertising: it’s a key event imported into Google Ads to measure campaign performance and guide bidding. In FullCheckApp reports, we still call key events conversions out of habit — they’re the same actions you marked in your GA4 property.
| Term | Where it’s used | What it means |
|---|---|---|
| Event | GA4 | Any recorded action: a page view, a click, a form submission |
| Key event | GA4 | An event marked as important to the business (with a star in the events list) |
| Conversion | Google Ads | A key event that ad campaigns and bid strategies optimize toward |
value | Event parameter | The monetary value of the action: the order total or an assigned value for a lead |
currency | Event parameter | The currency of the value, as a three-letter code: USD, EUR, GBP |
| Default key event value | GA4 settings | The amount GA4 assigns to a key event that arrives without a value of its own |
Why monitor conversions and their value?
Visitor counts don’t answer the big question: is your website making money? Conversions show how many people took the action you want, and value shows what those actions are worth. Together, they let you compare traffic channels by results instead of clicks: a thousand visitors from social media can bring in fewer orders than a hundred from search.
Without value, all conversions are equal: a request for a consultation and a big-ticket order count as one action each. That’s why online stores use the order total as the value, while service businesses often assign one — for example, their average revenue per lead. Google’s developer documentation stresses how important this parameter is:
“valueis typically required for meaningful reporting. […] If you setvaluethencurrencyis required for revenue metrics to be computed accurately.”
Currency also matters because GA4 converts all amounts into one — your property’s reporting currency. If a transaction comes in a different currency, “Analytics will perform the necessary conversion using the prior day’s exchange rate” (Google Analytics Help, Currency reference). So orders in euros and in dollars only add up correctly in one report if every event honestly states which currency its amount is in.
Finally, conversion tracking breaks silently. The website works and orders keep coming in, but analytics shows zero — and ad campaigns that optimize for conversions lose their bearings. A month-over-month comparison catches that kind of drop as soon as the first data comes in.
Why do conversions or their value disappear?
Usually it’s because of a change on the website or in the settings that stopped the event from firing, or made it fire incorrectly. Common causes:
- The tag or trigger is gone. After a website or Google Tag Manager container update, the purchase or lead event no longer fires.
- The event name changed. A key event is tied to a specific event name, such as
generate_lead. If a developer renames the event, the new name won’t become a key event on its own. - The event has no
value. Forms and buttons often send events without an amount. Then you get the conversion but no value — unless a default key event value is set up. - No
currency. The amount is sent without a currency code, so revenue metrics are calculated incorrectly. - The key event was marked recently. Marking an event as a key event only affects reports from that point on — it “doesn’t change historic data” (Google Analytics Help). So you won’t see conversions for earlier months in the report.
- The data is still being processed. According to Google, data processing in GA4 can take 24–48 hours, and the numbers for the last few days may still change (data freshness).
How do you spot a conversion tracking problem?
Compare conversions with your traffic and with your actual orders — the mismatch will point to the cause:
| What you see | Possible cause | What to do |
|---|---|---|
| Traffic is there, but conversions are zero from a certain day | The event stopped firing or was renamed | Place an order or submit a form yourself and look for the event in DebugView |
| Conversions are there, but the value is zero | The event arrives without value | Add value and currency to the tag, or set a default key event value |
| The value in the report doesn’t match your order totals | No currency, or the wrong currency | Check the currency code in the event parameters |
| Twice as many conversions as orders | The event fires twice — for example, when the thank-you page is reloaded | Check the triggers in GTM and the thank-you page code |
| A new key event has no history | Marking only applies from the time it was created | Compare only full months after the event was marked |
How to check conversions and their value yourself
The most reliable way is to complete a conversion yourself and see what GA4 received. Analytics has a DebugView report for exactly this:
“DebugView displays the events and user properties that Analytics collects from a user in real time, allowing you to troubleshoot issues as you install your tags or step through an external user’s live activity.”
- Turn on debug mode: open your website through Google Tag Assistant (tagassistant.google.com) or Preview mode in Google Tag Manager.
- Go through the conversion path: place a test order or submit a form.
- In GA4, go to Admin → Data display → DebugView and find your event. Click it and check the
valueandcurrencyparameters. - In the same Data display section, open Events and make sure the event is starred as a key event and its name matches character for character.
- To check without debug mode, use the Realtime report: it shows key events by name for the last 30 minutes.
- Or use the FullCheckApp “Conversion and conversion value monitoring” check and get the results in a clear visual format.
Don’t forget to delete or flag your test orders so they don’t skew your reports.
If you chose the last option, you’ve already made the right call: the check runs automatically, and you’ll be the first to know about any warning or critical issue.
What FullCheckApp checks
In the Analytics tab, FullCheckApp shows conversions from your GA4 property.
- Conversions by month — the number of GA4 key events, broken down by channel group, so you can see which source delivers results.
- Conversion value — for events that pass the
valueparameter, in your GA4 property’s currency. - Readable names — you can rename conversions, so instead of
generate_leadthe report shows, say, “Form lead.”
purchasegenerate_leadlast year: $1,300GA4 property currencyThere are no notifications for this data: it’s available in the tab. For the overall traffic picture, see GA4 website traffic monitoring; for ad spend and return, see Google Ads campaign monitoring in GA4. A sharp drop in conversions inside Google Ads itself is flagged by Google Ads conversion drop monitoring.
FAQ
What’s the difference between a key event and a conversion?
A key event is an event in Google Analytics 4 that you’ve marked as important to your business, such as a purchase or a lead. Google now uses “conversion” for an action that Google Ads campaigns optimize toward; it’s created from a key event. In other words, it’s the same action — the name depends on the tool.
Why does GA4 show conversions but no conversion value?
Most often, the event is sent without the value parameter. This is common with forms, call buttons, and sign-ups. Add value and currency to the event tag, or set a default key event value in GA4: it only applies to events without their own value, and only to future data.
Why do I need the currency parameter if all my sales are in one currency?
Google requires currency to be sent along with value so revenue metrics are calculated correctly. Your GA4 property’s currency and the event’s currency may differ, in which case Analytics converts the amount using the prior day’s exchange rate. Without a currency code, the value in your reports can be inaccurate, so always send both parameters together.
How many key events can I have in GA4?
According to Google’s Help, a standard GA4 property can have up to 30 key events, and an Analytics 360 property up to 50. In practice, a few are enough: purchase, lead, call, sign-up. The fewer key events you have, the easier it is to read reports and compare channels.
Will past conversions show up if I mark an event as a key event now?
No. A key event counts from the moment you mark it and doesn’t change historical data. The events themselves remain in GA4 for past periods, but they’ll only count as key events from now on. A new key event can take up to 24 hours to appear in standard reports.
Sources
- Google Analytics Help — Conversions vs. key events in Google Analyticssupport.google.com/analytics/answer/13965727?hl=en
- Google Analytics Help — Mark events as key eventssupport.google.com/analytics/answer/13128484?hl=en
- Google Analytics Help — About default key event valuesupport.google.com/analytics/answer/13749237?hl=en
- Google Analytics Help — Currency referencesupport.google.com/analytics/answer/9796179?hl=en
- Google Analytics for developers — Recommended events referencedevelopers.google.com/analytics/devguides/collection/ga4/reference/events
- Google Analytics Help — Monitor events in DebugViewsupport.google.com/analytics/answer/7201382?hl=en
- Google Analytics Help — Data freshnesssupport.google.com/analytics/answer/11198161?hl=en
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