How to Research Market Size for a SaaS Product as a Solo Founder

Why market size matters for solo founders

Market size determines your revenue ceiling. A micro SaaS in a market of 500 potential customers at $30/month has a ceiling of $15K MRR. The same product in a market of 50,000 potential customers has a ceiling of $1.5M MRR. Both can be great businesses, but you should know which one you are building.

For solo founders, the sweet spot is usually a market large enough for $10K-$50K MRR but small enough that big companies ignore it. This is the niche micro SaaS sweet spot.

The bottom-up method (most reliable)

Count your actual potential customers. How many people or companies experience the problem you want to solve? Use Reddit community sizes, LinkedIn job title searches, industry association data, and competitor user counts to estimate.

Then estimate conversion and pricing. If your market has 10,000 potential users, 2% conversion is realistic for a well-marketed micro SaaS, giving you 200 customers. At $30/month, that is $6K MRR.

• Reddit community sizes: r/subreddit member counts indicate interest level
• LinkedIn: search job titles to estimate professional market size
• Competitor data: check G2/Capterra for number of reviews as a proxy for user base
• Industry data: trade associations often publish market size figures
• Google Trends: relative search volume indicates awareness and demand

Using complaint data for market sizing

Complaint volume is a useful proxy for market size. If BigIdeasDB shows 500 complaints about a specific problem across platforms, the actual number of people experiencing it is likely 50-100x larger (most people do not leave reviews).

TrustMRR adds revenue context by showing what comparable products earn. If three competitors in your space each earn $20K-$80K MRR, the total market is supporting $60K-$240K in recurring revenue — and there may be room for a focused alternative.

Market size red flags and green flags

Green flags: multiple competitors earning revenue, active communities discussing the problem, growing complaint volume over time, and users describing willingness to pay.

Red flags: no competitors (market may not exist), shrinking community sizes, complaints about a product category dying, and users only interested in free solutions.

• Green: competitors earning $10K+ MRR in your space
• Green: growing Reddit community sizes and increasing complaint volume
• Green: users mentioning specific budgets or willingness to pay
• Red: no existing competitors or revenue in the space
• Red: all complaints focus on wanting free alternatives
• Red: market is consolidating around 1-2 dominant players with strong lock-in

FAQ