Conversion tracking is the foundation of all of Google Ads — but its importance actually reaches far beyond Google Ads alone. Without conversions, you can’t evaluate your marketing’s effectiveness at all: you don’t know which channels bring customers, how those channels work together, or whether your money is being spent wisely. This was the very first and most expensive mistake in the article on seven common mistakes, and here we look at it in more detail.
In short: Conversion tracking shows which ads, keywords, and channels actually bring results — leads, calls, sales. Without it, Google’s algorithm can’t optimize, you can’t see the return on your investment, and you can’t understand how your marketing channels work together. On a service site, conversions are usually a lead, a call, or an email click; in an online store, the main conversion is a purchase with its value, which allows optimizing for revenue. Common mistakes are no tracking, measuring the wrong things, and treating all actions as equal.
Why conversion tracking is critical
Imagine running a business but not knowing which ads bring customers and which just spend money. That’s exactly how Google Ads works without conversion tracking. But the problem is actually even bigger.
First, the algorithm can’t learn. Today, Google Ads relies heavily on automated bidding (Smart Bidding), which optimizes based on what you define as a conversion. If you don’t tell the algorithm what a conversion is, it defaults to optimizing for clicks — and clicks aren’t your business goal. You don’t want clicks, you want customers.
Second, and this is even more important — without conversions you can’t evaluate your business’s effectiveness at all. Conversions aren’t just a Google Ads feature — they’re the measurement system for your entire marketing. Without them, you don’t know:
- Which channels actually work. Do customers come from Google Ads, SEO, social media, or email? Without conversions you can’t compare them or understand where to put your money.
- How the channels work together. A customer rarely reaches a purchase with one touch. A typical journey looks like this: someone sees a Google Ads ad, leaves, returns later through remarketing, and buys only after an email. Who “made the sale”? Without conversion tracking, you can’t see that journey or each channel’s contribution.
- Whether the advertising pays off. Advertising is just one part of the whole. Conversions show whether your investment brings a return — not only in Google Ads, but across all your marketing.
This is exactly why conversion tracking is connected to everything else: it provides the data to make broad match and Smart Bidding work, it shows whether your budget pays off, and it’s the basis for every serious marketing decision.
What conversions there even are
Before we talk about mistakes, let’s look at what conversions even exist. They broadly fall into two groups depending on what kind of business you run.
A conversion is any action you consider valuable: a purchase, a lead, a call, a registration, a form submission. Some are primary (macro) — these are your actual business goal, such as a purchase or a lead. Others are intermediate (micro) — steps that lead toward the goal, such as adding a product to the cart or signing up for a newsletter.
The most important thing is to distinguish which conversions suit a service site and which suit an online store — because they’re completely different.
Conversions on a service site
If you offer services (you’re a consultant, a tradesperson, an agency, or a local service provider, for example), then your goal isn’t a direct online sale but contact — someone gets in touch with you. Typical conversions are:
- Form submission — a lead or quote request form. The clearest conversion on a service site.
- Call — a click on the phone number (especially on mobile) or an actual call.
- Email click — when someone clicks your email address to write to you.
- Requesting a quote or estimate.
- Chat — chat or WhatsApp, if you use it.
On a service site, most conversions are of roughly equal value — one lead is as good as another, at least at the level of basic measurement. So you usually count the number of conversions and optimize to get more leads at a lower cost.
Conversions in an online store
In an online store, the story is different. Here the sale happens directly online, and conversions are tied to the purchase process:
- Purchase — the main conversion. And here’s the critical detail: in a store you also need to pass the purchase value (value), not just the fact that a purchase happened.
- Add to cart — an intermediate conversion (micro).
- Begin checkout — a step toward the purchase.
- Registration or newsletter signup.
Why is passing the value so important? Because in a store not all purchases are equal. One customer buys for €20, another for €500. If you pass only “a purchase happened”, the algorithm considers them equal — and optimizes for the number of purchases. If you also pass the value, the algorithm can optimize for revenue, favoring customers who buy more.
This is the logic of ROAS (Return on Ad Spend): you don’t just want more purchases, you want more revenue per euro spent. Without passing the value, this can’t be measured or optimized.
Remarketing conversions
Remarketing is worth mentioning separately. Some of the actions you track — viewing a product, adding to cart, visiting a certain page — may not be a “purchase”, but are valuable as signals. Based on them you build a remarketing audience: people who showed interest but didn’t buy yet. Later you show ads to exactly those people again.
These signal conversions are part of the picture: they’re not your final goal, but they help build a strategy that brings interested people back. It’s important to label them correctly so you don’t confuse them with your primary conversions.
Common mistakes in conversion tracking
Now that the picture is clear, let’s look at what’s most often done wrong.
Mistake 1: no tracking at all. The most common and most expensive. The account works, ads show, money is spent — but no one knows whether there are results. The algorithm optimizes for clicks, not customers.
Mistake 2: measuring the wrong things. Sometimes tracking is set up but measures the wrong thing — for example a page load instead of a lead, or every button rather than the actual action. The result is data that looks good but means nothing.
Mistake 3: treating all actions as equal. If you count a newsletter signup as just as valuable as a purchase, you send the algorithm the wrong signal. It starts optimizing for cheap, easy “conversions” that don’t bring you real money.
Mistake 4: not passing the value in a store. As said above — without value, the algorithm optimizes for the number of purchases, not revenue, and you can’t see ROAS.
Mistake 5: double-counting. If a conversion is recorded multiple times (for example on every page refresh), the data shows more conversions than there actually were — and you make decisions based on the wrong numbers.
How to set it up correctly
Proper setup starts with one question: what is a real result for my business? On a service site it’s usually a lead or a call. In a store it’s a purchase with its value.
From there: define the primary conversions (macro) that the algorithm optimizes for, and separate them from the intermediate ones (micro) that you track for information but don’t optimize for. In a store, always pass the purchase value. And check regularly that tracking measures the right things and doesn’t create duplicates.
Technically, this works today through Google Tag and GA4, often together with Enhanced Conversions, which improve measurement accuracy. But the technology is secondary — the most important thing is to first establish what and why you’re measuring.
Summary
Conversion tracking isn’t a technical detail you can do later — it’s the foundation of all of Google Ads and at the same time the measurement system for your marketing. Without it, you can’t see results, the algorithm can’t optimize, and you don’t know which channels actually work and how they bring customers together.
On a service site, conversions are a lead, a call, and an email click. In an online store, the main conversion is a purchase with its value, which allows optimizing for revenue rather than volume. Separate the primary conversions from the intermediate ones and avoid the common mistakes: no tracking, measuring the wrong things, and treating all actions as equal.
If you want your conversion tracking set up correctly from the start — the right conversions, the right value, no duplicates — get in touch. Also see how our conversion tracking service works.