---
title: "Google Ads seasonality adjustments: what and when to use"
author: "Performetic Ekibi"
url: "https://www.performetic.com/en/blog/google-ads-seasonality-adjustments"
published: "2026-11-02T12:00:00.000Z"
updated: "2026-11-02T12:00:44.629Z"
---

# Google Ads seasonality adjustments: what and when to use

> A seasonality adjustment is a Google Ads tool that tells Smart Bidding in advance that conversion rates will change sharply for a short period. Google says it's ideal for 1-7 day sales and may not work as well beyond 14 days. Base the estimate on history, keep it conservative and raise budget alongside it.

## What is a seasonality adjustment in Google Ads?

A seasonality adjustment is an advanced Google Ads tool that tells Smart Bidding in advance that conversion rates will be meaningfully different over a set date range. Google says it's ideal for short events of 1-7 days, so your bid strategy doesn't react late to a flash sale or a Black Friday peak.

Smart Bidding learns from history. In a normal week that's a strength; in a three-day sale it becomes a weakness. By the time the algorithm notices the jump in conversion rate and raises bids, half the sale may be over. Seasonality adjustments exist to close that gap.

## How does a seasonality adjustment work?

When you create one, you set three things: start and end dates, scope (campaign types or specific campaigns) and the expected change in conversion rate. Google's help page uses a clear example: for a three-day sale where you expect conversion rates to rise by 50%, the adjustment increases the expected conversion rate by up to 50% for those three days.

One detail matters: you don't need a negative adjustment after the event. According to Google, campaigns return to normal performance once it ends. You can also create adjustments in a manager account and apply them across client accounts; accounts added afterwards don't inherit them automatically.

Adjustments aren't only for increases. If you know conversion rates will fall for a short period, such as a shipping outage, you can enter a decrease.

## Which campaign types and bid strategies support it?

According to Google's help center:

| Campaign type | Supported bid strategy | Note |
|---|---|---|
| Search | Target ROAS, Target CPA | Maximize strategies aren't listed |
| Shopping | Target ROAS, Target CPA | Standard Shopping campaigns |
| Display | Target ROAS, Target CPA | |
| Performance Max | Any bid strategy | The most common ecommerce scenario |
| App (beta) | Any bid strategy | |
| Travel | Not supported | |

If you run Manual CPC you don't need this tool; you already control bids yourself.

## When should you use a seasonality adjustment?

When all three of these hold:

- **The event is short:** 1-7 days. Google states plainly that adjustments may not work as well over periods longer than 14 days.
- **The change is large and predictable:** not a normal weekend wobble, but a spike the historical data has never seen.
- **The change has a new cause:** the algorithm already knows from past years that November is busier. Adjustments are for what it can't know: a 48 hour sale you've never run, a new promotion mechanic, a sold-out collection coming back.

Typical candidates: Singles' Day (11.11), the peak days of Black Friday week, short flash sales in late November and early December, and brand anniversary promotions. For planning the whole season, see our [Black Friday ad plan for ecommerce](/en/blog/black-friday-ad-plan-ecommerce).

## When should you not use it?

A mistake we see often is switching on an adjustment by reflex for every sale day. Skip it in these cases:

- **For all of November:** a month-long lift is already in the seasonal data, and long adjustments don't fit how the tool is designed.
- **When you're unsure of the effect:** enter +80% and get +20%, and the system overbids on those days. The result is low ROAS and spent budget.
- **When tracking breaks:** if a tag failed or the site went down, the right tool is a data exclusion, not a seasonality adjustment.
- **Every week:** constant adjustments get in the way of the algorithm's own learning and make results hard to read.

## How is it different from a data exclusion?

They sit side by side in Google Ads but solve different problems. A seasonality adjustment looks forward: "conversion rates will rise for the next three days." A data exclusion looks back: "conversion data from these days is broken, don't learn from it." Google designed data exclusions for tagging problems, site outages and data import failures, and they only work with conversion or conversion value based Smart Bidding strategies.

## How do you set up a seasonality adjustment step by step?

1. **Pull historical data.** Work out how much conversion rate changed in similar past events versus a normal day. Example: a normal rate of 1.5% that reached 2.4% during last year's three-day sale is a 60% lift.
2. **Keep the estimate conservative.** If the discount or product range is different this year, round down. Overestimating costs more than underestimating.
3. **Keep dates tight.** Cover only the hours the sale is actually live. Don't pad a day before or after.
4. **Choose the scope.** Select only campaigns affected by the event. Leave out campaigns for product groups that aren't on sale.
5. **Raise budget to match.** The adjustment raises bids; if budget is capped, that extra demand can't be bought. Example: an account spending $1,000 a day might plan $1,500-2,000 for those days.
6. **Watch hourly during the event.** If the real conversion rate is far below your estimate, remove the adjustment.
7. **Record the outcome.** Note the actual lift; next year's estimate comes from that number.

## A budget example for a three-day sale

Take an example account: a Performance Max campaign with a 500% target ROAS, a $1,000 daily budget and a normal 1.5% conversion rate. You expect 2.4% during a three-day sale. Without an adjustment, the system bids on day one using the old rate and traffic goes to competitors. With a 60% adjustment it knows from the first hour that clicks are worth more and bids up. If budget stays the same, those bids can exhaust it by midday, so the adjustment and the budget decision belong together. We explain how to set the target itself in our guide to [setting up Target ROAS bidding](/en/blog/how-to-set-target-roas-bidding).

## Does a seasonality adjustment trigger the learning period?

An adjustment doesn't change your bid strategy's settings; it adds a temporary correction to its forecast. So don't treat it like a strategy change. The real risk is changing target ROAS or adding and removing campaigns in the same days. Google says setting and composition changes like these can put a bid strategy back into learning, and calibration typically takes 1-2 conversion cycles. Avoid restructuring right before big sale days.

At Performetic we plan promotion calendars, seasonality adjustments and budgets together as part of our [performance marketing service](/en/services/performance-marketing). If you'd like to see what your account needs before the November peak, request a [free growth audit](/en/contact).

## Key takeaways

- A seasonality adjustment tells Smart Bidding in advance that conversion rates will change sharply for a short period.
- Google says it's ideal for 1-7 day events and may not work as well beyond 14 days.
- It works with Target ROAS or Target CPA on Search, Shopping and Display, and any strategy on Performance Max.
- Base the estimate on history, keep it conservative and plan a budget increase alongside it.
- For tracking failures, use a data exclusion, not a seasonality adjustment.

## FAQ

### How long should a Google Ads seasonality adjustment run?

Google says seasonality adjustments are ideal for short events of 1-7 days and may not work as well over periods longer than 14 days. Smart Bidding already learns broad lifts such as the whole of November from past data, so use adjustments only for the short days when a sale is actually live.

### Do seasonality adjustments work with Performance Max?

Yes. According to Google's help center, Performance Max campaigns support seasonality adjustments with any bid strategy. On Search, Shopping and Display, adjustments only apply to campaigns using Target ROAS or Target CPA. Travel campaigns aren't supported.

### Do I need a negative adjustment after the sale ends?

No. Google says campaigns return to normal performance after the event, so no negative adjustment is needed. Still, watch results for a few days afterwards; if you changed target ROAS or campaign structure in the same period, the bid strategy may have gone back into learning.

### What is the difference between a seasonality adjustment and a data exclusion?

A seasonality adjustment looks forward and tells Smart Bidding that conversion rates are about to change. A data exclusion looks back and keeps conversion data from days with tagging errors, site outages or import failures out of learning. Don't use a seasonality adjustment to fix a tracking problem.

## Sources

- [Google Ads Help: About seasonality adjustments](https://support.google.com/google-ads/answer/10369906)
- [Google Ads Help: About data exclusions](https://support.google.com/google-ads/answer/10370710)
- [Google Ads Help: Duration of the learning period for campaigns](https://support.google.com/google-ads/answer/13020501)