In marketing, the percentage of a market’s total sales generated by one company is called market share.
Market share compares a company’s sales with the sales of all competitors in a defined market and period. It can be calculated using revenue or units sold. For example, a firm selling 20 million units in a market selling 100 million units has a 20% unit market share.
The definition of the market matters. A company can have a high share in a narrow category but a low share in a broader category. Revenue share and unit share can also differ when competitors charge different prices. Analysts therefore state the geography, customer segment, product boundary, measure, and time period.
Market share is not the same as market penetration, which commonly describes the proportion of potential customers who use a product or category. Share of voice measures advertising presence, not sales.