Google Ads vs. Microsoft Ads: how to split a budget between search engines
Splitting budget by market share is the wrong method. What matters is the cost of a conversion in each channel for you. How the two platforms really differ, and the order in which to test the second one.
- Market share is not the key to splitting budget: what decides is the cost of a conversion in each channel for you.
- Microsoft Ads is a supplement with its own budget and its own target, not a shrunken copy of Google Ads.
- Importing campaigns one to one is the most common mistake — and the reason the second channel then goes unmanaged.
“Let us do fifty-fifty, to be fair” is a sentence that has cost companies real money. Splitting budget between search engines is not a question of fairness or of loyalty to a smaller player. It is a question of where the same money buys more business.
Shares are context, not a formula
Google dominates search in almost every European market, typically holding somewhere above 80–90 %, with Bing in the low single digits to around ten per cent depending on the country. Local engines matter in a handful of markets — Seznam in the Czech Republic, Naver in South Korea, Yandex in parts of Eastern Europe — and are irrelevant elsewhere.
Those shares tell you which channel can supply volume. They tell you nothing about which supplies cheaper conversions, because they say nothing about competition, conversion rate or the demographics behind them. A platform with 4 % of searches can still be worth running if its clicks are half the price and convert as well.
The practical differences you only see in the account
| Area | Google Ads | Microsoft Advertising |
|---|---|---|
| Volume of demand | Orders of magnitude larger; for most queries the only meaningful source of scale | Small, but in some categories disproportionately stronger than the share suggests |
| Cost per click | Higher competition, but better tools for managing it | Usually cheaper clicks, especially outside the most contested categories |
| Bidding automation | Mature strategies, many signals, but also a lot of black box | Automated strategies exist but have less data to learn from |
| Shopping | Merchant Center, Performance Max, sophisticated feed structure | Feed import from Google is straightforward; the auction is thinner |
| Audience | The whole market | Skews towards corporate devices and older age groups — relevant for some B2B |
| AI surfaces | Ads inside AI Mode and AI Overviews | Ads can appear inside Copilot answers |
| Import | — | Near-automatic import of Google campaigns, which is both the advantage and the trap |
How to split a budget: a method, not a maxim
The rule “split by market share” makes no sense, because it ignores conversion rate and cost per click. An honest approach has four steps:
- Start with Google. It has the volume and gathers data faster, which is what lets you evaluate anything at all. If the budget is not enough for Google, the second engine will not save it.
- Give the second engine a separate test budget. Not the leftovers after Google, and not a proportional slice. Enough that it gathers sufficient conversions in a month to be evaluated — otherwise you will never learn anything about it.
- Compare cost per conversion, not cost per click. A cheaper click is bait, not a result. What decides is what an order or enquiry costs in each channel, measured with the same conversion definition.
- Shift gradually. The channel with the lower cost per conversion that is still losing impressions to budget gets more. The other gives up some. Evaluate after each step, exactly as with any other budget increase.
The most common outcome we see in accounts: Google takes the majority of the budget, the second engine is a minority but with a markedly better cost per conversion on brand and local queries, and worse on generic ones. Which means it should not run as a shrunken copy of Google.
Where a second search engine typically earns best
- Brand queries. Cheap and with a high conversion rate. Mind the same trap as with Google though: brand takes credit for people who would have arrived anyway. See brand vs. non-brand.
- B2B and corporate devices. Where the default browser on a work machine matters, the share of the smaller engine is higher than the national average.
- Local and regional queries. Services, trades, premises outside the largest cities.
- Older demographics. In some categories, a measurably different audience from Google.
Where the mistakes happen
- Copying the structure. Importing campaigns one to one. Smaller volume means fine-grained ad groups will never gather data — on a smaller engine the structure belongs coarser.
- Automated strategies on low volume. They need conversions. At a handful a month, sensible manual control beats a strategy with nothing to compute from.
- A different conversion definition. When you measure orders in Google and also add-to-cart on the other platform, you are comparing incomparables. This is the most common reason one engine “comes out better” or “worse”.
- Missing analytics integration. Without it you cannot tell what the second channel really brought, and the decision gets made on numbers from its own interface.
- Forgotten campaigns. The second engine often gets switched on and then not looked at for a year. A dead channel without upkeep is worse than none, because it looks like diversification.
What to take away
A second search engine is neither an obligation nor an obsolete relic. It is a smaller channel that, given its own structure and its own target, can deliver conversions at a good price — and that, when run as a copy of Google, quietly spends money. The decision is made on data from your own account, not on market share, and it is evaluated on cost per conversion with an identical conversion definition in both systems. Where it fits among other channels is covered in Microsoft Ads, LinkedIn and other channels.
Common questions
Is Microsoft Advertising worth running alongside Google Ads?
In some cases yes, but as a supplement with its own budget and its own structure, not as a copy of your Google campaigns. It tends to do best on brand and local queries, in B2B where corporate devices matter, and with older demographics. Decide by testing: give it a separate budget large enough to gather sufficient conversions in a month, and compare cost per conversion rather than cost per click.
How should I split budget between search engines?
Not by market share. Start with Google Ads, because it has the volume and the data, then give the second engine a separate test budget and after a month compare cost per conversion using an identical conversion definition in both systems. Then shift budget gradually towards whichever delivers cheaper conversions while still losing impressions to budget. Evaluate after each step before taking the next one.
Can I just import my Google campaigns into Microsoft Ads?
You can, and it takes minutes — which is exactly the trap. Smaller volume means that fine-grained ad groups imported from Google will never gather enough data for automated strategies to work, and the account then quietly underperforms. After importing, consolidate the structure into something coarser, review the negative keyword lists, and set a realistic target. And put a recurring reminder in the calendar, because imported accounts are the ones most often left unmanaged for a year.