Size your market bottom-up: total, serviceable and obtainable market from customer counts and price.
TAM (total addressable market) is everyone who could ever buy this kind of product, times what they'd pay in a year. SAM (serviceable addressable market) is the part you can actually reach with your product, language, region and channels. SOM (serviceable obtainable market) is the slice you can realistically win in the next few years.
Investors and your own planning care most about SOM. A $40B TAM means little if you can only reach a few thousand people; a small, reachable SOM that pays well is a better start than a huge market you can't get into.
Top-down sizing takes an industry report number and claims a percentage of it. Bottom-up sizing - what this calculator does - counts the customers you could name and multiplies by your real price. It's more conservative and far more convincing, because every number can be checked.
For a solo founder, a realistic obtainable share is usually low single digits. If the business only works at 20% market share, the market is too small or the price too low.
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