Market Capitalization Calculator
Calculate a company's market cap from share price and shares outstanding.
Includes size classification: nano-cap to mega-cap.
What Is Market Capitalization?
Market capitalization (market cap) is the total market value of all a company’s outstanding shares. It is the most common way to measure a company’s size.
Formula
Market Cap = Share Price × Shares Outstanding
For example: if a company trades at $50 per share and has 200 million shares outstanding, its market cap is $50 × 200,000,000 = $10 billion.
Market Cap Classifications
| Classification | Market Cap Range | Examples (approximate) |
|---|---|---|
| Nano-cap | Under $50 million | Very small startups, penny stocks |
| Micro-cap | $50M to $300M | Small regional companies |
| Small-cap | $300M to $2 billion | Growing mid-size companies |
| Mid-cap | $2B to $10 billion | Established companies |
| Large-cap | $10B to $200 billion | Blue-chip stocks |
| Mega-cap | Over $200 billion | Apple, Microsoft, Amazon, etc. |
Those boundaries are conventions, not rules. Index providers draw them in slightly different places, and a company near a line can be classified as mid-cap by one provider and small-cap by another. It matters because index funds are forced buyers and sellers when a stock crosses a boundary at a rebalance.
Why Market Cap Matters
Market cap is how you compare companies of different shapes across industries. It is also the basis for the major indices: the S&P 500 weights by market cap, so the largest handful of companies drive most of the index’s movement regardless of how the other 400-plus perform. Larger companies are generally steadier with slower growth. Smaller ones move further in both directions.
Shares outstanding is not shares you can buy
Market cap uses every share in existence, including those locked up by founders, insiders, and governments. The tradable portion is the free float, and it can be dramatically smaller. A company can carry a $40 billion market cap while only 15% of its shares ever change hands, which makes the price move on far less volume than the headline number suggests. Index providers usually weight by float, not by full cap, for exactly this reason.
Price alone tells you nothing about size
This is the most common beginner error. A $700 share price does not make a company large, and a $3 share price does not make it small. Both depend entirely on how many shares the company chose to issue. A stock split doubles the share count and halves the price, and the market cap does not move at all. Only the multiplication of the two means anything.
Market Cap vs. Enterprise Value
Market cap counts equity only. Enterprise Value (EV) adds the company’s debt and subtracts its cash, which is the number an acquirer actually cares about, because buying the company means taking on its debt and getting its cash. A business with a $10 billion market cap, $5 billion of debt, and $1 billion of cash has an EV of $14 billion. For heavily indebted industries such as airlines and telecoms, the two figures diverge enormously.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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