Help me calculate TAM, SAM, and SOM for my startup using both top-down and bottoms-up approaches.

My product: [ONE SENTENCE - WHAT IT DOES]

Ideal customer: [WHO SPECIFICALLY BUYS THIS - BE PRECISE ON COMPANY SIZE, INDUSTRY, GEOGRAPHY, ROLE]

Pricing model: [HOW YOU CHARGE - E.G., "$99/MONTH PER SEAT" OR "$500/MONTH FLAT" OR "2% TRANSACTION FEE"]

Average expected revenue per customer per year: [$X]

Geography (starting market): [E.G., US, UK, EUROPE, GLOBAL]

Known competitors or alternatives: [WHAT DO CUSTOMERS USE TODAY?]

Please generate:

TOP-DOWN APPROACH

Start with the broadest relevant market and narrow down:

• Total industry/category spend globally (cite sources or logical estimates)
• Narrow by geography → your starting market
• Narrow by customer segment → only your ICP
• Narrow by willingness to adopt/buy → realistic penetration

Show the math at each step.

BOTTOMS-UP APPROACH

Start with countable customers and build up:

• Estimated number of companies/people that match your exact ICP
• Expected conversion rate from awareness → customer (be conservative: 1-5%)