The essentials
- SEA: immediate, controlled and measurable visibility, which stops with the budget; cost per click rising with competition.
- SEO: visibility that is slow to obtain (3 to 12 months), lasting, whose marginal cost per visit falls over time; dependent on Google and on competitors.
- Together: SEA tests and covers what SEO does not cover yet; SEO reduces dependence on budget; the data flows between the two.
- The split: mostly SEA at launch, rebalancing towards SEO as the rankings arrive; never one without the other beyond a year.
The aim of SEA (search engine advertising, Google Ads first among them) and SEO (organic search) target the same results page and the same intentions, through two opposite mechanisms: one buys visibility at auction, the other earns it through relevance. The question of which to choose comes up mainly at launch and when the budget is tight; the answer depends on the time horizon and the situation. This article compares the two point by point, says when one wins, and suggests a split. The more operational trade-off is covered in Google Ads or SEO.
Point-by-point comparison
| Criterion | SEA (Google Ads) | SEO |
|---|---|---|
| Time to first results | A few hours | 3 to 12 months |
| Lifespan | Stops with the budget | Months or years after the effort |
| Cost | Per click (€0.50 to €10 and more depending on the sector), rising with competition; plus 10 to 20% management | Content production, technical work, links; marginal cost per visit that falls over time |
| Control | Total: queries, areas, times of day, messages, budget, immediate stop | Low: Google decides the ranking, competitors move |
| Measurement | Precise: cost, clicks, conversions by keyword | Good (Search Console, GA4) but with no cost per query |
| Placement | Top and bottom of the page, Shopping, Maps, YouTube, Display | Organic results, snippets, local pack, AI overviews |
| User trust | Some users avoid ads | Organic results are seen as more trustworthy |
| Click-through rate | 2 to 6% on Search | 25 to 35% in position 1, 10 to 15% in position 3 |
| Scalability | Linear with the budget, with diminishing returns | Non-linear: a well-ranked piece of content pays off with no extra cost |
| Lock-in | On the budget and on market CPCs | On the algorithms and AI overviews |
When SEA wins
- Launch: a new site has no authority; SEA brings the first customers while SEO is being built.
- Seasonal offer or promotion: visibility tied to a date, impossible to obtain through SEO in time.
- Testing: validating an offer, a message, an area or a keyword in a few days before investing in content.
- Highly competitive queries where the first organic page is locked up by national players.
- Areas outside the local pack's radius for a local business; see bringing local into SEO and SEA.
- Remarketing: bringing back the visitors who came from SEO and did not convert.
When SEO wins
- Long horizon: a business that will still be there in two years is better off building an asset than renting its visibility.
- Informational queries: guides and definitions do not pay for themselves through advertising, but they build awareness and feed the AI overviews.
- Sectors with high CPCs (legal, insurance, B2B software) where each paid click costs €5 to €30; an organic position is worth thousands of euros a month.
- Low margin: the cost per click leaves no room; SEO stays profitable.
- Trust: professions where users avoid ads.
Making the two work together
| From SEA to SEO | From SEO to SEA |
|---|---|
| The search terms that convert become pages and topics | The queries where the site already ranks 1 to 3 are scaled back or excluded in Ads |
| The winning ad headlines inspire the title tags and descriptions | Well-ranked pages serve as landing pages (Quality Score) |
| The profitable areas and audiences guide the local pages | SEO content feeds remarketing |
| SEA covers the queries while the rankings are awaited | The SEA budget freed up by SEO funds new queries |
| Holding both the ad and the organic position on the same query increases total clicks (the “double presence” effect, measured at between 10 and 25%) |
The point of contact is the shared dashboard: queries, cost, clicks and conversions from both channels in the same place, with brand searches tracked separately. The measurement method is in the Google Ads KPIs and tracking your SEO rankings.
Splitting the budget
| Situation | Indicative split | Why |
|---|---|---|
| Launch, new site | 70% SEA, 30% SEO (technical foundations and pillar content) | Customers straight away, an asset being built |
| Growth, 6 to 18 months | 50 / 50 | SEO starts to pay; SEA targets what is not covered yet |
| Maturity, established rankings | 30% SEA, 70% SEO and content | SEA focuses on remarketing, promotions, and the areas and queries outside SEO |
| E-commerce | Mostly SEA all year round (Shopping) + SEO on the categories and guides | Shopping is hard to replace; see SEA and e-commerce |
| Low margin or prohibitive CPCs | Mostly SEO, SEA on brand and remarketing | The paid click is not profitable |
How GreenRed helps
Rather than juggling several tools, GreenRed's overview brings these metrics together in a single dashboard, compares them over time and tells you which actions come first. You can try it free, with no card, from the Pricing.
Frequently asked questions
Should you do SEA if you already rank well?
Yes, in a targeted way: remarketing, promotions and seasonal offers, competitive queries where organic hits a ceiling, uncovered areas, brand protection if competitors bid on it. On the queries where you are already in positions 1 to 3, double presence brings a click gain of 10 to 25%; test it before cutting.
Does SEA improve organic search?
Not directly: Google has always said that ads do not influence organic ranking. Indirectly, SEA brings data (the terms that convert, the messages that get clicks), traffic that sometimes generates links and brand searches, and funds the time it takes to build SEO.
What is the minimum budget to start SEA and SEO?
In SEA, €300 to €600 a month for one area and one service, more in competitive sectors. In SEO, an initial audit (€1,000 to €3,000) then €500 to €1,500 a month of content and monitoring for an SME. The two together often represent €1,000 to €3,000 a month at the start.
Is SEO free?
No: it costs content production time, technical work and link building, in-house or via a provider. Its difference from SEA is that the marginal cost per visit falls over time, since a well-ranked page keeps paying off with no extra spend.