Shopping campaign performance fluctuations: Bids and bid targets

Your performance may fluctuate if your bids, bid limits, or bid targets are set without taking into consideration the historical data Google Ads will use to serve your ads.

What you can do

Setting bids

When setting bids, bid limits, or targets for your bid strategy, use historical data to understand if the bids, bid limits or targets you are setting are appropriate to maintain performance. 


If you have been losing impression share due to ad rank with your current bids, setting a lower bid limit than your current average CPCs can potentially cause further performance fluctuations.

Smart bidding

For Smart Bidding, we recommend using historical data and choosing bids within a close range of the actual averages to minimize fluctuations in performance.


If your actual average ROAS (conversion value/cost x 100) has been around 100% for the past 14 days, suddenly increasing your Target ROAS to 500% can cause a drop in serving, or fluctuations in performance more broadly.

If you need to make changes to your targets in alignment with your business goals, we recommend making incremental changes at a time and waiting for a while to see the impact, instead of making large changes.

Need something else?

Check other common reasons why your campaign performance is fluctuating.

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