Your conversion rate is dropping, but you don't know why—and GA4's interface isn't making it obvious. You need a reliable way to check conversion trends in real time, spot performance drops before they compound, and understand which traffic sources and devices are actually converting.
Define Your Conversion Event
GA4 doesn't have a preset "conversion" metric. You define it by marking specific events as conversions in your property settings.
Fire conversion events with gtag
Fire events when conversions happen on your site using gtag('event', ...). GA4 automatically tracks purchase, sign_up, and custom events. You can send conversion value and item details in the event payload.
// Fire a purchase conversion
gtag('event', 'purchase', {
'currency': 'USD',
'value': 99.99,
'items': [{
'item_id': 'SKU_12345',
'item_name': 'Premium Plan',
'price': 99.99,
'quantity': 1
}]
});
// Or a signup conversion
gtag('event', 'sign_up', {
'method': 'google'
});Mark events as conversions in Admin
Go to Admin > Events > Conversions in your GA4 property. Toggle Mark as conversion for each event you want counted. This tells GA4 to include it in conversion rate calculations, conversion funnels, and attribution reports.
View Conversion Rate in Real Time
Once conversion events are tracked, you can see live conversion rate in the GA4 dashboard and dig deeper with custom reports.
Add a Conversion Rate card to your dashboard
Open your GA4 property home. Click + Add a card and select Metric. Search for Conversion rate. GA4 calculates this as conversions ÷ sessions. Now you have a live number. Segment it by Device category and Source / Medium to spot weak channels.
Query conversion rate with the Reporting API
Use the GA4 Data API to pull conversion rate programmatically. This lets you push data to dashboards, trigger alerts, or compare against baselines. Request the conversionRate metric along with dimensions like device or traffic source.
// Query GA4 Reporting API for conversion rate by source
const request = {
property: 'properties/YOUR_PROPERTY_ID',
dateRanges: [{
startDate: '2024-01-01',
endDate: 'today'
}],
metrics: [
{ name: 'conversions' },
{ name: 'sessions' },
{ name: 'conversionRate' }
],
dimensions: [
{ name: 'firstUserSource' },
{ name: 'deviceCategory' }
]
};
const response = await client.properties.runReport({
property: request.property,
requestBody: request
});Set Up Alerts for Conversion Rate Drops
Don't wait for weekly reports. Monitor conversion rate in real time and alert when it drops below your baseline.
Establish your baseline conversion rate
Open Explore and select Conversion rate as your metric. Run it over the last 30 days. Note the average—this is your baseline. If it's 5%, a drop to 4% is a red flag. Use this number to trigger alerts.
Query Real Time API and alert on drops
Use GA4's Real Time API to check conversion rate every 10 minutes. If it drops below your baseline, send an alert to Slack, email, or your monitoring service. Real Time data is updated with a 3–5 minute delay, so don't panic on the first blip.
// Query GA4 Real Time API
const response = await analyticsData.properties.runRealtimeReport({
property: 'properties/YOUR_PROPERTY_ID',
metrics: [
{ name: 'conversions' },
{ name: 'sessions' },
{ name: 'conversionRate' }
]
});
const conversionRate = parseFloat(
response.totals?.[0]?.metricValues?.[2]?.value || 0
);
// Alert if below baseline (e.g., 0.05 = 5%)
if (conversionRate < 0.05) {
// Send alert
console.warn(`⚠️ Conversion rate: ${(conversionRate * 100).toFixed(2)}%`);
}Common Pitfalls
- Forgetting to mark events as conversions—GA4 tracks them automatically, but they won't count toward conversion rate until you toggle Mark as conversion in Admin.
- Not accounting for data latency—Real Time API has a 3–5 minute delay. Wait 10 minutes before acting on a sudden drop.
- Using conversion rate in isolation—a healthy rate can hide a drop in absolute conversions. Always check both together.
- Tracking the wrong event as a conversion—if you mark page views or bounces as conversions, your rate becomes worthless. Be precise about what counts.
Wrapping Up
Now you can monitor conversion rate live, spot drops before they spiral, and understand which channels and devices drive revenue. You're no longer guessing. If you want to track conversion rate automatically across GA4, Amplitude, and other tools in one place, Product Analyst can help.