A big sale is coming and you know conversion rates will jump for a few days. Smart Bidding does not know that yet. Google Ads seasonality adjustments let you tell it in advance, so bids move with the event and return to normal afterward. This guide explains what they do, when they help and when to leave them alone.
In this guide: What Google Ads Seasonality Adjustments Do | When to Use Them | How Long an Adjustment Should Run | Which Campaigns Support It | How to Size the Adjustment | Budget Still Matters | Adjustments and Ad Scheduling | Managing Several Accounts | Frequently Asked Questions | Final Thoughts
What Google Ads Seasonality Adjustments Do
According to Google’s page on seasonality adjustments, an adjustment is a scheduled change to your expected conversion rate. It can be an increase or a decrease, and it covers an upcoming event such as a sale or promotion.
Without it, bidding learns from results after the fact. With it, the system knows the change is coming and bids for it during the event window. When the window ends, it goes back to normal without you adding a second adjustment to undo the first.
When to Use Them
Use an adjustment only when you expect a major change in conversion rate. Google states that Smart Bidding already handles regular seasonal patterns, so a normal weekend or a predictable monthly cycle does not need one.
Good fits include:
- A flash sale or limited-time offer that will lift conversion rates sharply.
- A launch or promotion with a clear start and end date.
- A known disruption, such as a short period when you cannot fulfil orders or take enquiries, which will push conversion rates down.
Poor fits include slow drifts in demand, gradual growth and anything with no clear end date.
How Long an Adjustment Should Run
Google says the tool works best for short events of about 1 to 7 days. It also warns that results may suffer if you apply an adjustment for long periods, such as more than 14 days at a time.
That guidance shapes how you plan. If a promotion runs for three weeks, a single adjustment for the whole period is the wrong tool. Reserve it for the sharpest part of the event, such as launch weekend or the final days, and let normal bidding handle the rest.
Which Campaigns Support It
Support depends on campaign type and bid strategy, so check this before you plan around it. Google’s page lists these combinations:
- Search, Shopping, Demand Gen and Display campaigns that use Target ROAS or Target CPA.
- Performance Max and App campaigns (App is in beta) on any bid strategy.
- Travel campaigns are not supported.
If your campaigns use manual bidding, an adjustment will not help. Our guide to Smart Bidding covers which strategies suit which goals.
How to Size the Adjustment
Size it from your own data. Look at how conversion rate behaved during the last comparable event and use that as your starting point. Google gives a simple example: if you expect a 50% lift over a 3-day sale, you enter an increase of up to 50% for those three days.
Here is a hypothetical case. Say a store normally converts at a round 2% and expects roughly 3% during a weekend sale. That is a 50% lift in conversion rate, so a 50% increase for the weekend is a reasonable entry. If you are unsure, enter a smaller number than your estimate. An adjustment that is too large can push bids up faster than the results justify.
Budget Still Matters
A higher expected conversion rate usually means higher bids and faster spend. If your daily budget is the same as on a normal day, the campaign may run out of budget early in the day and miss the evening peak.
Plan the budget before you set the adjustment. Our guide on how much to spend on Google Ads helps you set a figure you can sustain, and it is worth raising the cap for the event days.
Adjustments and Ad Scheduling
Seasonality adjustments change the expected conversion rate for a window of days. Ad scheduling changes when your ads run or how much you bid at certain hours. They solve different problems, and they can work side by side.
If your event only converts during certain hours, review Google Ads ad scheduling as well, so the two settings do not pull against each other.
Managing Several Accounts
If you run client accounts, Google lets you create one adjustment from a manager account and apply it to linked accounts. You can scope it to a campaign type or to specific campaigns. Note that accounts linked after you apply the adjustment do not inherit it, so check any new account by hand.
If you are still choosing a bid strategy, see our comparison of target CPA vs target ROAS.
Frequently Asked Questions
Do I need an adjustment for every holiday?
No. Smart Bidding already handles regular seasonal patterns. Save adjustments for events where you expect a major shift in conversion rate that bidding has not seen before.
What happens after the event ends?
Bidding returns to normal after the scheduled window, so you do not need to enter a second adjustment to reverse the first.
Can I run one for several weeks?
Google advises against it. Results may suffer when an adjustment runs more than 14 days at a time, so keep it to short, sharp events.
Final Thoughts
Google Ads seasonality adjustments are a precise tool for short events with a clear conversion rate change. Keep them brief, size them from past results, match the budget to the expected demand and review the outcome afterward so the next event is easier to plan.
Want expert help with your account? See our Google Ads management service.