Overlap rate is a Google Ads metric that shows how often a competitor’s ad received an impression in the same auction where your ad also received one. It appears for each competitor in auction insights and is measured as a share of your own impressions.
How overlap rate works
Every time your ad is shown, Google notes which other advertisers’ ads were shown alongside it on the same results page. Overlap rate is the percentage of your impressions where a given competitor appeared too. If a London locksmith’s report shows a national firm with an overlap rate of 70%, then seven in every ten times the locksmith’s ad appeared, the national firm’s ad was on the page as well.
It is reported for Search and Shopping campaigns and can be run for a campaign, an ad group or a set of keywords. You can segment it by time and device, which is where it becomes most useful. Your own row shows impression share; overlap rate only applies to the other advertisers. In Shopping campaigns the same idea applies to product listings: it shows which retailers’ products appeared in the same results as yours, which matters for an online shop competing on price for the same branded items.
Auction insights only shows advertisers who competed in the same auctions, not which keywords they used to get there. A rival might be bidding on different words, or on broad match keywords that happen to match the same searches.
Why it matters
Overlap rate tells you who you actually meet in front of customers, which is often not the list of competitors you would write down. A local firm you worry about may overlap only 10% of the time because it runs ads only during office hours or in a smaller area, while a business you have never heard of sits next to you most of the time.
Changes over time are just as telling. A rising overlap rate with one competitor usually means they increased budget, added keywords or widened their location targeting. If you know who you meet most often, you can write ads that stand apart from theirs rather than saying the same thing in the same space.
Common mistakes
- Confusing overlap rate with impression share. Impression share is about how often you appear at all; overlap rate is about how often a rival appears with you.
- Assuming a low overlap rate means a competitor is not interested in your market. They may run out of budget early, only advertise at weekends, or target a different area.
- Reading it on its own. Overlap tells you how often you meet; position above rate and outranking share tell you who usually wins.
- Assuming the competitor is bidding on your exact keywords.
How to act on it
Run auction insights for your main campaigns over 30 to 90 days and note the three or four advertisers with the highest overlap. Then segment by day of the week and by device. If a strong rival disappears on Sundays or on desktop, your ads face less competition at those times, which may justify a bid or budget test there, provided conversions hold up.
Where overlap is high and the competitor usually ranks above you, look at the ads side by side and ask what a searcher would see as the difference. Improving the offer, the ad text and the landing page tends to pay back better than simply bidding higher. Reviewing competitors this way is part of my Google search ads management.