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Seasonality adjustment

A seasonality adjustment is a note to Google's Smart Bidding that the conversion rate will jump or drop for a few days, for example during a short sale.

How it works

Smart Bidding predicts the conversion rate of each auction from past data, so it cannot know about next week’s sale. A seasonality adjustment gives it the expected change for set dates and chosen campaigns. An adjustment of +50% (a modifier of 1.5) means a conversion rate one and a half times the usual one. The adjustment applies only between its start and end dates.

Google calls adjustments ideal for short events of 1–7 days and warns they may work less well beyond 14 days. The Google Ads API accepts no more than 14 days. An adjustment covers listed campaigns or all campaigns of chosen types (Search, Shopping, Display), optionally on some devices only. When to use one is the subject of seasonality adjustments in Google Ads.

Example

Example store, not client data.

The tableware shop plans a three-day sale and expects its conversion rate of 3.75% to rise by half. It sets a +50% adjustment on its Shopping campaign for those three days, so bidding works from about 5.6% (3.75% × 1.5). On the fourth day bidding goes back to its usual forecast.

How GetProfit reads it

The portal’s methodology limits an adjustment to 14 days and rules out raising target ROAS during a peak. Instead, a seasonal peak gets its changes two weeks ahead: budget up by 20–30%, target ROAS down by 10–15%. Assortment and seasonality shows whether your store has a season at all.

Not to be confused with

  • Seasonality — demand that repeats every year. An adjustment is for a short jump of a few days.
  • Data exclusion — tells Smart Bidding to ignore data from dates when tracking was broken. It cleans up the past, while an adjustment looks ahead.

Right and wrong readings

  • Wrong: “November is our peak, so we add an adjustment for the whole month.” Right: an adjustment is for short events. Google calls them ideal for 1–7 days, and the API accepts no more than 14.
  • Wrong: “After the sale we need a negative adjustment to bring bids down.” Right: an adjustment applies only between its start and end dates, so the next day bidding works from its usual forecast.

Sources