TAM-Based SEO Forecasting

Forecast SEO opportunity top-down from market size, not bottom-up from keyword tools

Eli Schwartz
Rethinking SEO in the age of AI

TAM-Based SEO Forecasting

"When you do this top-down, you're closer to the truth. Now, you probably aren't going to get to the truth. I've never seen a product plan get to the truth of what it could do, but it will help you make a better decision than if you just guess." - Eli Schwartz

What It Is

TAM-Based SEO Forecasting is a top-down approach to sizing SEO opportunity that starts with market size rather than keyword search volumes. Traditional "bottoms-up" SEO forecasting uses keyword research tools to estimate traffic potential—but these tools are often wrong by factors of 10x in either direction.

Instead of asking "how many people search for this keyword?", this framework asks "how many people in my target market could potentially find me through search?" It applies TAM (Total Addressable Market) thinking to SEO planning.

How It Works

The Problem with Bottoms-Up Forecasting:

  1. You look up keyword search volumes in tools like Semrush, Ahrefs, or Similarweb
  2. You estimate your potential ranking position and click-through rate
  3. You multiply to get expected clicks, then apply a conversion rate
  4. You "gross up" by 10x to account for long-tail keywords
  5. Result: A number that's often wildly inaccurate because keyword tools are wrong

The Top-Down Alternative:

  1. Start with your total market size (population, businesses, etc.)
  2. Apply filters for your target segment (demographics, behaviors)
  3. Estimate what percentage uses online search for this problem
  4. Calculate your realistic market share capture
  5. Result: A number you can actually defend and adjust

Why Keyword Tools Fail:

  • Google doesn't share real search volumes (even for Google Ads)
  • All tools use proprietary algorithms to estimate
  • Tools often overestimate or underestimate by 10x
  • Eli Schwartz worked with WordPress where every keyword tool had completely wrong numbers compared to Google Search Console

How to Apply It

Step 1: Define your market

  • Total population or businesses in your target geography
  • Example: Japan has 100 million people

Step 2: Apply segment filters

  • Gender, age, company size, industry, etc.
  • Example: 50% male = 50 million; 50% of target age = 25 million

Step 3: Filter for online behavior

  • What percentage buys this category online?
  • What percentage uses search (vs. social, recommendations)?
  • Example: 10% buy shoes online = 2.5 million potential searchers

Step 4: Estimate market share

  • What share of online searchers can you realistically capture?
  • Based on your competitive position and SEO strength
  • Example: 10% market share = 250,000 potential customers

Step 5: Calculate value

  • Multiply by average order value and purchase frequency
  • This is your SEO opportunity ceiling

Adjusting Over Time:

  • Unlike bottoms-up forecasts, you can go back and adjust any assumption
  • "My AOV was wrong" or "Market share was lower than expected"
  • Each variable can be tuned based on real data

When to Use It

TAM-Based Forecasting works best when:

  • You're entering a new market or geography
  • You need to justify SEO investment to leadership
  • Keyword tools give you numbers that seem too small (or too large)
  • You want a defensible forecast you can adjust

It's especially useful for:

  • International expansion planning
  • New product launches
  • Executive presentations and business cases
  • Comparing SEO opportunity across markets

Bottoms-up may still help for:

  • Understanding relative search demand (keyword A vs. B)
  • Identifying how people phrase searches (user journey mapping)
  • Normalizing data (not absolute numbers)

Example Calculation

Launching a shoe e-commerce site in Japan:

Step Filter Number
Total population Japan 100,000,000
Target gender Men only 50,000,000
Target age 25-55 25,000,000
Online shoe buyers 10% buy online 2,500,000
Search channel 40% use search 1,000,000
Market share 10% capture 100,000
Annual purchases 2x/year 200,000 orders
AOV $80 $16M opportunity

Each assumption can be challenged and refined, but you now have a framework for the conversation.

Source

  • Guest: Eli Schwartz
  • Episode: "Rethinking SEO in the age of AI | Eli Schwartz (SEO advisor, author)"
  • Key Discussion: (01:37:11) - TAM-based forecasting as alternative to keyword research tools
  • YouTube: Watch on YouTube

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