Free calculator
Market Cap Calculator
Work out a company's market capitalisation from its share count and price, see which size band it falls into, and calculate enterprise value including debt.
Market capitalisation
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Enter a share count and price.
- Size category
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- Enterprise value
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- Net debt
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- P/E ratio
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- Free float cap
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Runs entirely in your browser. Nothing is sent or stored.
The formula
Market cap = Shares outstanding × Share price
500 million shares at $40 gives a market cap of $20 billion. That is roughly what it would cost to buy the entire company at the current quote, ignoring the fact that trying to buy it all would move the price considerably.
Size categories
| Category | Market cap | Typical characteristics |
|---|---|---|
| Nano-cap | Under $50M | Very thin liquidity, high manipulation risk |
| Micro-cap | $50M – $300M | Wide spreads, minimal analyst coverage |
| Small-cap | $300M – $2B | Volatile, higher growth potential and failure rate |
| Mid-cap | $2B – $10B | Established but still growing |
| Large-cap | $10B – $200B | Liquid, widely covered, index constituents |
| Mega-cap | Over $200B | The largest companies in the world |
These bands matter in practice. Smaller caps have wider bid-ask spreads and thinner order books, which means higher real trading costs and more slippage, factors the position size calculator cannot see but your P&L will.
Enterprise value: the fuller picture
Enterprise value = Market cap + Total debt − Cash
Market cap prices the equity. Enterprise value estimates the cost of the whole business, because an acquirer inherits the debt and receives the cash.
The difference can be dramatic. Two companies both at $20B market cap are not comparable if one carries $15B of net debt and the other holds $10B of net cash; their enterprise values are $35B and $10B. Comparing them on market cap alone is comparing the wrong thing.
Free float and index weighting
Not every share is available to trade. Founders, governments and insiders hold blocks that are locked up or simply never sold. Free float counts only the genuinely tradeable portion.
Most major indices weight by free float rather than total market cap, because the restricted shares cannot be bought. A company with a 30% float has far less index weight, and far thinner real liquidity, than its headline market cap suggests.
Frequently asked questions
How do you calculate market cap?
Multiply the number of shares outstanding by the current share price. A company with 500 million shares trading at $40 has a market capitalisation of $20 billion. It is the price of buying every share at the current quote.
What are the market cap categories?
The common US bands are nano-cap under $50 million, micro-cap $50 to $300 million, small-cap $300 million to $2 billion, mid-cap $2 to $10 billion, large-cap $10 to $200 billion, and mega-cap above $200 billion. The boundaries are conventions rather than rules and shift over time.
Is a higher share price the same as a bigger company?
No, and this is the most common misunderstanding in investing. A $600 share price tells you nothing about company size; it depends entirely on how many shares exist. A company with 10 million shares at $600 is far smaller than one with 5 billion shares at $30.
What is enterprise value?
Enterprise value is market cap plus total debt minus cash. It estimates what it would cost to buy the whole business outright, because an acquirer takes on the debt and gets the cash. For companies carrying heavy debt, enterprise value can be far larger than market cap.
What is free float market cap?
Free float market cap counts only the shares available to trade, excluding those held by founders, governments or locked up by insiders. Most major indices weight companies by free float rather than total market cap, because the restricted shares are not really purchasable.