How big is the company really? Enter the share price and shares outstanding to get market capitalization — the total value of all shares — and see which size tier (mega, large, mid, small, micro) the stock falls into.
Answer first: market capitalization is simply the share price multiplied by the number of shares outstanding. It is the headline number investors use to measure a company’s size — far more meaningful than the share price alone, because a $10 stock with 10 billion shares is worth vastly more than a $1,000 stock with a million shares.
Market cap = Share price × Shares outstanding
Example: $150 × 2,000,000,000 shares = $300 billion — a large-cap company. The calculator also shows that a $1 move in the share price changes the whole company’s value by the share count (here, $2 billion).
The common U.S. classifications used by index providers and brokerages are:
| Tier | Approximate market cap |
|---|---|
| Mega-cap | $200 billion and up |
| Large-cap | $10 billion – $200 billion |
| Mid-cap | $2 billion – $10 billion |
| Small-cap | $300 million – $2 billion |
| Micro-cap | $50 million – $300 million |
| Nano-cap | Under $50 million |
Size is a rough proxy for risk and behaviour. Mega- and large-cap stocks tend to be established, widely-followed and less volatile; they dominate indices like the S&P 500, which is weighted by market cap. Small- and micro-caps can grow faster but swing harder and trade with wider bid-ask spreads. Diversifying across sizes is one reason index funds spread risk so effectively.
Market cap counts only the equity. Enterprise value adds debt and subtracts cash to estimate what it would cost to buy the whole business outright. Two companies with the same market cap can have very different enterprise values if one is loaded with debt — worth remembering when you compare valuations.
Reality check: use fully diluted shares outstanding (including options and convertible securities) for the most accurate figure; the basic share count understates true size. Share counts change with buybacks and new issuance, so always pull the latest number from the company’s filings. Educational tool only — not financial advice.
Learn more in what is market cap, then value the business with the P/E ratio, EPS and price-to-book calculators.
Last updated 27 June 2026 · Written by Mustafa Bilgic. Educational only — not financial advice.
Multiply the current share price by the total number of shares outstanding. A $150 stock with 2 billion shares has a market cap of $300 billion.
Large-cap generally means a market capitalization between roughly $10 billion and $200 billion. Above $200 billion is often called mega-cap; below $10 billion down to $2 billion is mid-cap.
No. Share price alone says nothing about company size because it depends on how many shares exist. A $1,000 stock with few shares can be smaller than a $10 stock with billions of shares. Market cap is the real measure.
Use fully diluted shares outstanding for the most accurate market cap, since it accounts for stock options and convertible securities that could increase the share count.