Hey! It’s Théo today. We’ll speak about the topic of smarter decision-making in Google Ads. If you want to know whether your budget is driving real value or just feeding low-performing queries, the Lin Rodnitzky Ratio is the KPI you need.

Let’s break it down.What Is the Lin Rodnitzky Ratio?

The Lin Rodnitzky Ratio is a diagnostic metric used to assess how effectively you're investing across your search queries. It compares the cost per acquisition (CPA) of all search queries with the CPA of only those queries that have converted at least once.

Formula:
Lin Rodnitzky Ratio = CPA (all search queries) ÷ CPA (converting queries only)

This ratio gives a clear signal on whether your Google Ads spend is being directed toward results or wasted on irrelevant traffic.

Why This Metric Matters in Paid Search

Most Google Ads accounts get the majority of their results from a small subset of search queries. The rest? Often noise.

That’s where this ratio shines. It helps you:

Identify if your spend is concentrated on high-performing keywords

Detect inefficiencies in non-converting or low-quality search terms

Understand if you're over-testing or playing too safe

It’s one of the fastest ways to assess search traffic quality in an account, especially in high-volume or long-tail environments.

How to Interpret the Ratio

Here’s what the values usually tell you:

A ratio close to 1

You’re very conservative. Most of your budget is going to converting queries. That sounds good, but you might be missing opportunities to scale or test new angles.

A ratio above 2

A red flag. A few queries are doing all the heavy lifting while the rest drag your performance down. You’re likely spending a significant share of budget on traffic that never converts.

The sweet spot? Around 1.5

You’re testing new queries but maintaining control. This balance is ideal in most search engine advertising strategies.

How to Use the Lin Rodnitzky Ratio in Practice

Pull data by search term in Google Ads or via a report from your MCC dashboard

Calculate your total CPA

Filter to queries with at least one conversion and calculate CPA again

Divide both numbers

If you find your ratio is above 2, it’s time to act:

Add negative keywords to cut waste

Reallocate budget to top performers

Reassess match types or audience layering

For PPC experts managing multiple accounts, this ratio is a quick and powerful way to audit campaign health at scale.

Combine It with Other Signals

The Lin Rodnitzky Ratio gives you clarity but not the full picture. Always combine it with:

Impression share lost due to budget

Conversion value per cost

Search terms with assisted conversions

Quality Score trends

This gives you a complete view of traffic quality, keyword intent, and budget efficiency.