About the Market Share Calculator
This market share calculator divides your sales by total sales in the market to give your market share, then goes further: it compares you with your largest competitor (relative market share), shows your share last period and the change in percentage points, and tells you whether you are growing faster or slower than the market as a whole.
It is built for marketers, founders, analysts and students preparing a business plan, a board update or a BCG growth-share matrix. Use revenue for value share or units sold for volume share — just keep the same measure for your company, your competitor and the total market.
Market share is only as good as the market definition behind it. Total market sales should cover the same products, geography and period as your own figures, typically from an industry association, a research report or public filings. Relative market share above 1.0 means you are the market leader.
With the default inputs, the market share is 15%. Change any value above to recalculate instantly.
How to use the market share calculator
- 1Decide on the market definition and measure (revenue or units).
- 2Enter your sales and total market sales for the period.
- 3Enter your largest competitor’s sales for relative share.
- 4Add last period’s figures to see share change and growth.
- 5Read your share, relative share and whether you are outgrowing the market.
Formula and method
Market share is your sales as a percentage of all sales in the defined market over the same period. It can be measured by revenue (value share) or by units (volume share); the two differ when your prices are above or below the market average.
Relative market share, popularised by the BCG growth-share matrix, divides your sales by the largest rival’s. A value of 0.5 means you are half the leader’s size; above 1.0 means you are the leader (in that case compare with the next-largest firm). The change in share is shown in percentage points, and comparing your growth rate with the market’s explains whether you are gaining or losing ground.
- your sales
- Your revenue or units in the period
- total market sales
- Sales of all companies in the same market and period
- largest competitor
- Sales of the biggest rival (or next-largest if you lead)
Worked examples
$4.5M brand in a $30M market
$4.5M ÷ $30M = 15% share, half the size of the $9M leader (30%). Last year $3.6M of $27M was 13.33%, so share rose 1.67 points because your sales grew 25% while the market grew 11.1%.
Market leader measured in units
Selling 120,000 of 400,000 units is a 30% volume share. Against the next-largest rival at 80,000 units, relative share is 1.5, confirming market leadership. No prior period was entered, so change is zero.
Growing but losing share
Sales grew 10% to $2.2M, but the market grew 25% to $50M, so share fell from 5% to 4.4% — a loss of 0.6 points despite higher revenue.
Frequently asked questions
How do you calculate market share?+
Divide your company’s sales by the total sales of the whole market over the same period and multiply by 100. For example, $4.5 million of sales in a $30 million market is a 15% market share.
What is relative market share?+
Relative market share compares your sales with your largest competitor’s: your sales ÷ their sales. A result of 0.5 means you are half their size, and anything above 1.0 means you are the market leader.
Should I use revenue or units for market share?+
Either works if you are consistent. Revenue (value share) reflects pricing power, while units (volume share) shows how many customers choose you. Premium brands often have a higher value share than volume share.
Where can I find total market size?+
Common sources are industry association reports, government statistics, market research firms and competitors’ public filings. You can also estimate it bottom-up with the market size calculator from customer counts and spend.
Can my sales grow while my market share falls?+
Yes. If the overall market grows faster than you do, your share shrinks even as revenue rises. Comparing your growth rate with market growth shows whether you are truly gaining ground.