The Market Size section on pitch decks is valuable real estate but is often a missed opportunity in our experience. Here are some suggestions to make this section of your pitch work for you at the seed and early stages:

How much will be spent on your category in 2026 according to analysts is moderately interesting but often of limited relevance in the context of early-stage VC rounds. The relevant market segment may be nascent. It is often unclear what’s included in the analyst forecasts, and what part of that is addressable by the offering in question.

For most SaaS startups, we find that a simple bottom-up estimate can be very effective: # of target customers x Average annual deal size
e.g. 100,000 customers x $10K ACV = $1B TAM
This can help both you and your audience think through deal sizes and the breadth of your target market. For arriving at the number of addressable customers, triangulate from various publicly available data points, e.g. # of customers of a comparable large public company, NAICS-based data from public agencies, revenue thresholds for Global 2000 or S&P 500, # of B2B companies that have raised growth stage rounds etc. Ensure that the assumption for # of target customers applies relevant segmentation E.g. if your target customer set is logistics providers above 100 employees, then develop a good sense of how many such providers there are in your target geographies.

If you plan to broaden your product, target segments, and/or geographies over time, you could include progressive TAM numbers, e.g.
Phase 1: 50,000 customers x $10K ACV = $500M TAM
Phase 2: 100,000 customers x $50K ACV = $5B TAM

If your product will replace an alternate mode (e.g. manual work), include what is spent today to meet the need. This is often just one reference point. Customers don’t usually replace their spend dollar for dollar.

Make sure the number your bottom-up TAM shows is realistic and addressable by your product/vision in 5-10 years. A trillion-dollar TAM is great. But very rarely realistic for early-stage companies.

Some rare situations may merit getting into SAM and SOM, but I typically recommend the above keep-it-simple approach for seed and early rounds in enterprise/SaaS.

When done well, a simple bottom-up TAM analysis can help advance your own thinking about how you may build a venture-scale business. It will also lead to richer discussion during the pitch, and convey to your VC that you are thoughtful and serious about building venture scale.

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