Should you spend your budget on search engine optimisation (SEO) or on Google Ads? Both bring leads from people searching for your service, but they cost money in different ways. Google Ads charges for every click. SEO costs time or a monthly fee, and the traffic keeps coming once the pages rank. This calculator compares the cost per lead of both channels side by side, and shows the value of your organic traffic in ad terms.
Enter your ad budget and cost per click, your organic traffic and your monthly SEO cost. The tool shows the number of leads and cost per lead for each channel, plus the traffic value line that tells you what your organic visits would cost if you paid for them.
Compare the two channels
Google Ads
SEO
How the two channels differ
Google Ads is paid per click. You can switch it on today, control the budget, and target exact searches, locations and times. When you stop paying, the leads stop. Ads are fast, but the cost of each lead depends on how many people click and how many of them become enquiries.
SEO is slower to start. It can take months for a page to rank, and the work needs steady effort on pages, reviews, links and technical health. The reward is that traffic keeps coming after the work is done, and the cost of each visit drops as the traffic grows.
The formulas
- Ads clicks: budget ÷ cost per click
- Ads leads: clicks × landing page conversion rate
- Ads cost per lead: budget ÷ ads leads
- SEO leads: organic visits × organic conversion rate
- SEO cost per lead: SEO cost ÷ SEO leads
- Organic traffic value: organic visits × cost per click
The traffic value line is useful in client conversations. It does not mean you would have paid that amount, but it shows what the same visits would cost in ads. A site with 2,000 organic visits and a $5 cost per click has a traffic value of $10,000 a month, which makes the SEO work easier to justify.
Worked example
A local electrician spends $1,000 a month on Google Ads. The average cost per click is $8, so the ads bring 125 clicks. The landing page converts 4% of clicks into calls, which gives 5 leads and a cost per lead of $200. The same electrician has 900 organic visits a month, converts 3% into leads, and pays $400 a month for SEO. The SEO leads are 27, and the cost per lead is about $15. The organic traffic value is $7,200 a month. On these numbers, SEO is far cheaper per lead, although it needed time to build.
When Google Ads is the better choice
- You need leads this week, for example for a new service or a seasonal rush.
- Your business is new and has no organic traffic yet.
- The keyword is very competitive and the organic ranking is far away.
- You want to test an offer before you change the site.
When SEO is the better choice
- You will serve the same area for years and want lower cost per lead over time.
- Your site already gets organic traffic that is not converting well.
- Your customers search with problem words, such as leak repair or roof replacement cost.
- You have the time or budget for steady work on pages and reviews.
Common mistakes in the comparison
- Comparing ads with SEO at different points in time. A new SEO project cannot be compared fairly with a campaign that has run for a year.
- Leaving out the SEO cost. If you do the SEO yourself, put a dollar value on your hours.
- Ignoring the landing page. The same traffic can give very different leads depending on the page.
- Using average CPC for every keyword. Some services cost much more per click than others, so check the price for your top keywords.
Pros and cons of this calculator
The SEO vs Google Ads calculator is most useful when you plan a budget for the next 6 to 12 months. Many businesses use paid ads for quick leads and SEO for long-term lower cost per customer.
Pros
- Compares the cost per customer of SEO and Google Ads on one screen.
- Shows how many months of SEO work it takes to match the cost of paid traffic.
- Helpful when your budget is limited and you must pick a first channel.
- Lets you test different close rates and job values.
Cons
- SEO results take months, so the first months can look expensive.
- Google Ads stops bringing leads the day the budget stops.
- Ad cost per click changes with competition and season, so inputs need updating.
- The result does not include brand value or the traffic that SEO brings to other pages.
Use the pros and cons together with the numbers above. A result is only as good as the inputs, so check your lead and spend figures against your real records before you make a budget decision.
Frequently asked questions
Should I stop Google Ads when SEO starts working?
Not always. Many businesses keep a small ad budget for the best keywords and use SEO for the long tail. Compare the cost per lead of both channels every month and move budget to the cheaper one.
How accurate is the traffic value?
It is an estimate. Use the cost per click for the keywords your organic pages actually rank for, not the average for your industry.
Can I use this for a service business with calls?
Yes. Count each call that becomes a qualified enquiry as a lead, and use the same number for both channels so the comparison stays fair.
How to fill in the numbers
Use the last three months of data for each input. For Google Ads, the cost per click and the conversion rate are in your ads account and your analytics tool. For organic traffic, use the sessions from Search Console or Analytics for pages that rank for service keywords, not the whole site. For SEO cost, add the monthly fee and a fair value for your own time. Leave out brand searches, which would have come to you anyway, and leave out traffic from existing customers who return to the site.
If you are not sure about a number, enter a range and run the calculator twice, once with the low value and once with the high value. The result shows whether the decision changes. If the cheaper channel wins in both runs, you can act with confidence. If the answer flips, collect more data before you move your budget.
Related free tools and next steps
Start with the Cost Per Lead Calculator to understand the price of one enquiry, then use this tool to compare channels. The Ranking Drop Revenue Loss Calculator shows what a drop in organic traffic costs you each month. The Review Gap Calculator helps you plan the reviews that support both channels. For a full plan that compares your organic and paid options, see our SEO audit service, or check your page snippets with the free SERP checker.