A sale is approaching and you want Google Ads ready for it. Should you add a seasonality adjustment, increase the budget, or leave the campaign alone?
Start with what you expect to change. More people searching, a larger advertising allowance and a higher likelihood of buying are different things. A conversion-rate seasonality adjustment tells Smart Bidding about an anticipated change in that last measure during a defined event.
For most businesses, the calendar alone is not a reason to use it. Google says Smart Bidding already handles seasonal events and reserves these adjustments for substantial, temporary conversion-rate changes. Its current seasonality guidance identifies one to seven days as the ideal duration.
Does Black Friday automatically need an adjustment?
No. In its October 2026 discussion of bidding and budgets, Google explains that its systems already recognise major holiday patterns. A business-specific change, such as a substantially different offer or a promotion outside the usual shopping dates, can provide a stronger reason for an adjustment.
Ask what customers will encounter that makes them more likely to complete the action you measure. A compelling offer on available products might change purchase behaviour. Simply expecting more visitors does not establish that a greater proportion will buy.
Use this decision table before opening the settings:
| Your situation | Practical starting point |
|---|---|
| A short promotion with credible evidence of a substantial conversion-rate change | Consider a conversion-rate seasonality adjustment for the affected campaigns. |
| Normal holiday demand, with no meaningful change expected in conversion rate | Let Smart Bidding account for seasonality; review whether the commercial offer and spending allowance are suitable. |
| A promotion lasting several weeks | Plan budgets, targets and the offer across that period rather than stretching a short-event adjustment. |
| Missing or unreliable conversion tracking | Investigate measurement before estimating promotional uplift. |
Google’s bid-strategy decision guide advises against seasonality adjustments for normal changes in audience mix or seasonal periods exceeding seven days. Although the overview warns particularly about use beyond 14 days, that is not a recommendation to fill a fortnight with an adjustment.
Estimate the change in conversion rate, not the discount
The percentage entered is your expected relative change in conversion rate. It is not the percentage discount on your products, your desired sales increase or the extra amount you want to spend.
For an illustrative calculation, a conversion rate moving from 2% to 3% represents a 50% relative increase: the one percentage-point difference divided by the original 2%. That arithmetic explains the input; it does not predict what any particular promotion will achieve.
Build the estimate from comparable evidence in your own account. Consider the same products, campaign scope, conversion action and type of offer. Check whether previous periods included stock shortages, tracking changes or a different customer mix. A sitewide average can be a poor basis for a promotion affecting one product range.
Small samples also deserve caution. A handful of purchases can produce a dramatic percentage change without providing a dependable forecast. If there is no credible baseline, do not manufacture an uplift just to complete the setting.
For retail Performance Max, Google’s current retailer best-practice guide recommends using existing campaigns with conversion history. It gives a change above 30% as an example of a significant shift, rather than a universal requirement or a promise that an adjustment will help.
Check the campaign and bidding strategy
For the common campaign types considered here, Google’s creation instructions support Search and Standard Shopping using Target CPA or Target ROAS, and Performance Max using all its bidding strategies.
Check the actual campaign type and saved strategy before preparing the change. Do not assume that a Search campaign using Maximise clicks qualifies because it advertises the same sale as your Performance Max campaign.
Keep the scope tied to the offer. If only one product range is discounted, identify which campaigns contain it and whether they also advertise substantial amounts of unaffected stock. An account-wide estimate needs evidence that the wider account will experience the same change.
For a service business, ask the equivalent question about enquiries. Is the offer likely to increase suitable enquiries, and can the team handle them? An increase in form submissions is less useful if most requests concern work you cannot supply.
Keep conversion-rate signals and budgets separate
Google also offers seasonal budget adjustments. These schedule a temporary increase in average daily budget and have their own eligibility rules. They are a different adjustment type from the conversion-rate signal discussed here. Google says these budget changes affect the monthly spending limit in the same way as ordinary budget changes.
Decide the affordable promotional allowance independently. Include the cost of the discount, fulfilment, payment handling and likely returns when judging what a sale is worth. More revenue does not automatically mean more money left after costs.
If the campaign is already constrained, use our guide to Google Ads campaigns limited by budget to review that decision separately.
Google’s October 2026 discussion also describes promotion mode rolling out for Search and Performance Max, with scheduled promotional bidding and budget changes. That is another distinct control. Check what your account actually offers and record which changes you intend to make; the announcement does not establish that every account has the option.
Set up the adjustment with a clear owner
Once the evidence supports it, follow this sequence using Google’s creation instructions linked above:
- Open Tools > Budgets and bidding > Adjustments, then the Seasonal section.
- Create an adjustment and select Conversion rate as the adjustment type.
- Name the event clearly and enter its start and end dates.
- Select the intended campaign scope and enter the estimated relative conversion-rate change.
- Review the details before saving and creating the adjustment.
Have the person responsible for the offer confirm the timing. Check that the advertising event, website discount and any product-feed promotion refer to the same period. Verify the relevant time-zone displays rather than assuming that midnight means the same thing in every connected system.
Keep a short change record: campaigns, baseline evidence, estimate, event period, spending allowance and reviewer. This gives the team something concrete to check if the offer changes or is cancelled.
Test the buying journey before the event
Before launch, follow the advertised route on a phone as well as a computer. Check the landing page, promoted products, discount conditions, stock and checkout. For lead generation, submit a clearly identified test enquiry and confirm that the right team receives it.
Ask whoever maintains measurement to verify the genuine completion action and, where relevant, the recorded purchase value. If a campaign is treating browsing activity as a lead, our guide to page views counted as Google Ads leads explains the checks.
If measurement breaks, avoid using a promotional estimate to disguise the problem. Google’s data-exclusion guidance addresses conversion-tracking and upload outages separately. Have the specialist assess the affected period and appropriate recovery; an exclusion is not a substitute for repairing tracking.
Agree who will watch the campaign and who can authorise a change. Define a practical response if stock runs out, the checkout fails or the business cannot fulfil the advertised offer. Check those operational facts during the event, alongside spend and enquiries.
Review completed outcomes after the sale
Google says campaigns stop using the adjustment after its scheduled end; you do not need an opposite adjustment just because the promotion has finished. That does not guarantee that sales, competition or costs will return to their earlier levels.
Check separately that promotional wording and discounts have ended, and review any budget or target changes made alongside the adjustment. Those decisions need their own review.
Avoid judging the final hour of a sale as though every purchase is already recorded. Google’s conversion-lag reporting guidance explains that the delay between an advert click and a conversion can temporarily make cost per acquisition look higher and return on ad spend look lower. Use the account’s conversion-delay evidence to choose an appropriate review date.
Compare completed purchases or qualified enquiries, advertising cost and the commercial value left after the offer. Record whether the estimated conversion-rate change was plausible. A stronger sales period alone does not prove that the adjustment caused the improvement: the offer, demand and other campaign changes may also have contributed.
Planning a short promotion? Talk to BuzzBoost about checking the campaign, customer journey and measurement before the offer starts. Bring the dates, promoted products or services, past campaign evidence and affordable allowance so the review can reach a practical decision.
Featured image: AI-generated editorial artwork, not a photograph of a real BuzzBoost office, client or result.
