Market sizing

market share

a company's product sales as a percentage of total sales for that industry

market

a group of buyers and sellers of a particular good or service

Total Addressable Market (TAM)

is also known as the total available market. It the total market demand for a product or service. Let's say you are starting a fast food chain. Your TAM would be the worldwide fast food restaurant market. Potentially, if you were present in every country and had no competition you would generate TAM as revenues.

Bottom Up Approach

is an analysis that is calculated by estimating potential sales in order to determine a total sales figure. A bottom up analysis evaluates where products can be sold, the sales of comparable products, and the slice of current sales you can carve out. While it takes a lot more effort, the result is usually much more accurate.

Top Down Approach

is calculated by determining the total market, then estimating your share of that market. A typical top down analysis might go something like this: "Hmm... I will sell a widget everyone can use, and since there are 300,000 people in my area, even if I only manage to land 5 percent of that market I'll make 15,000 sales."

market size

is made up of the total number of potential buyers of a product or service within a given market, and the total revenue that these sales may generate.

Serviceable Obtainable Market (SOM)

is the portion of SAM that you can capture. It is also know as market share.

Serviceable Available Market (SAM)

is the segment of the TAM targeted by your products and services which is within your geographical reach.