Best practice: 5-15 tightly related keywords per ad group in Google Ads. Too few limits reach; too many forces generic ads that reduce Quality Score. Each ad group should target a single clear search intent that can be addressed with one set of ads.
How many keywords per ad group is one of those deceptively simple questions with a genuinely nuanced answer. The right number depends on your keyword match types, campaign type, and how tightly you want to control your targeting. This guide gives South African advertisers the practical framework for making this decision. Related: How to structure a Google Ads campaign.
The 5-15 Keyword Rule of Thumb
The widely accepted best practice for Search campaigns is 5-15 keywords per ad group. This range is large enough to capture meaningful search volume and small enough to ensure all keywords share a coherent search intent that a single set of ads can address effectively.
The fundamental logic: every keyword in an ad group should be answerable by the same ad. If you would need to write a completely different ad to address one of your keywords compared to the others in the group, that keyword belongs in a different ad group. When keywords and ads are perfectly aligned, Quality Score improves, CTR improves, and cost per click decreases.
What Happens With Too Many Keywords Per Ad Group?
Ad groups with 30, 50, or 100+ keywords are usually a sign of poor account structure. With that many keywords, it is virtually impossible to write an ad that is genuinely relevant to every keyword. Google ends up showing loosely relevant ads to loosely relevant searches, resulting in lower CTR, lower Quality Scores, higher CPCs, and worse conversion rates.
The search terms report for bloated ad groups typically reveals a wide range of loosely related searches being triggered, many of which should be in separate ad groups with their own tailored ads. The fix is splitting the ad group into multiple smaller, tighter groups — each with fewer keywords and more specific ads.
What Happens With Too Few Keywords Per Ad Group?
Single Keyword Ad Groups (SKAGs — one keyword per ad group) were popular from 2015-2020 as a way to achieve maximum relevance. Today, they are generally considered unnecessary overhead. Google’s Responsive Search Ad format handles keyword variation within an ad group effectively, and the proliferation of match type close variants means that even Exact Match keywords cover multiple search variations. SKAGs create management complexity without proportional performance benefit in most accounts.
How to Group Keywords Correctly
Group keywords by search intent, not by word similarity. ‘Emergency plumber Cape Town’ and ’24 hour plumber Cape Town’ have similar words and the same intent — they belong in the same ad group. ‘Plumber Cape Town’ and ‘plumbing services Cape Town’ also share intent. But ‘drain unblocking Cape Town’ and ‘burst pipe repair Cape Town’ represent different specific problems — consider whether they need different ad copy before combining them.
- All keywords in one ad group should trigger the same ad without confusion
- Group by problem (‘drain blockage’) rather than by generic service (‘plumbing’)
- Separate high-value keywords into their own groups for individual bid control
- Use naming conventions that make the group’s intent clear: ‘Drain Unblocking – Cape Town’
Ad Groups for Different Campaign Types
The 5-15 keyword rule applies primarily to Search campaigns. Display campaigns target audiences rather than keywords and typically have 1-2 targeting criteria per ad group. Shopping campaigns do not use keyword-level ad groups — products are grouped by category or product type. Performance Max campaigns do not have traditional ad groups — they use asset groups instead.
For South African businesses running their first Search campaigns, starting with 3-5 ad groups of 5-10 keywords each keeps the account manageable while still providing meaningful segmentation. See the Google Ads ad group best practices for additional guidance.
Frequently Asked Questions
Should I separate branded and non-branded keywords into different ad groups?
Yes — always put branded keywords (searches for your company name) in a separate campaign, not just a separate ad group. Branded keywords have fundamentally different competitive dynamics, conversion rates, and bidding needs compared to generic service keywords. Separating them allows you to control budget allocation between brand and non-brand traffic independently.
What is a single keyword ad group (SKAG)?
A SKAG is an ad group containing only one keyword. This approach was popular in the mid-2010s for maximising keyword-to-ad relevance. It is now considered outdated for most accounts because Google’s match type close variants and Responsive Search Ad format handle variation more efficiently than creating hundreds of single-keyword ad groups.
How many ad groups should a campaign have?
For a local South African service business, 3-8 ad groups per campaign is the right starting range. Each ad group represents a distinct service or problem category. As the account grows and you have conversion data showing which ad groups perform best, you can expand or restructure accordingly.
Do keyword quantities affect budget distribution?
Keywords do not have budgets — campaigns do. Budget distribution within a campaign is determined by which ad groups generate the most auction-eligible impressions. Ad groups with more keywords and broader match types will typically consume more budget. If certain ad groups are consuming disproportionate budget relative to their performance, either tighten the keywords or reduce their individual keyword bids.
How often should I review my keyword lists?
Review your search terms report weekly during the first 90 days of a new campaign, then monthly once it has stabilised. Each review should add high-performing new searches as keywords and add irrelevant searches as negatives. This process continuously improves targeting precision over time.