Full market cap values a company using every share outstanding. Float market cap values only the shares the public can actually trade, so it leaves out blocks held by insiders, founders, governments and other long-term holders. The float figure is never larger than the full figure, and the gap between them tells you how much of a company is really available to buy and sell.
That gap matters more than it sounds. It changes how big a stock looks in an index, how easily large orders move its price, and whether two “market cap” numbers from two websites can be compared at all. Below, we walk through both definitions, the math, a worked example and a short checklist you can use before trusting any cap figure.
Marketcaplensmarketcaplens.comCompare Company Size and Tradable FloatMarketCapLens brings together company rankings, share prices, historical data, and sector breakdowns to help you explore market trends.Explore company data| Full market cap | Float market cap | |
|---|---|---|
| Shares counted | All shares outstanding, including restricted and insider holdings | Only shares available for public trading |
| Formula | Share price × total shares outstanding | Share price × floating shares |
| Size | Larger or equal | Smaller or equal |
| Best for | Ranking company size, quick valuation comparisons | Index weighting, liquidity and supply analysis |
| Main risk | Overstates what the market can actually buy | Depends on how each provider defines “available” |
If every share of a company trades freely, the two numbers are the same. They split apart when large holders are unlikely to sell.
Start with three share counts, because people mix them up. Authorized shares are the most a corporation may issue. Outstanding shares are the ones it has actually issued. Float is the publicly tradable subset of those outstanding shares, a distinction Investopedia lays out in its explainer on a company’s float.
Float is found by taking outstanding shares and subtracting restricted stock. That includes insider shares that are locked up for a period, for example after an IPO, so they cannot be sold into the market yet, per the same Investopedia explanation.
S&P Dow Jones Indices uses the same idea in its index education material. It describes public float as shares available for public trading and says it leaves out large non-trading blocks, such as holdings of founders, executives and government agencies, in its guide to the S&P 500 and the Dow.
For a deeper look at the share-count side, see our explainer on shares outstanding vs. float.
Full market capitalization is the value of a corporation worked out by multiplying the current market price per share by the total shares outstanding, as Investor.gov defines it. Nothing is subtracted. Every share counts the same, whether it trades daily or sits in a founder’s account.
FINRA stresses this point: outstanding shares include publicly traded shares plus restricted shares held by company officers and insiders. Its example is simple. A company with 5 million shares at $20 has a market cap of $100 million.
That is the number most people mean when they say a company is “a $100 million company” or “a large cap.” If you want the formula in more depth, including how restaurant stocks and other sectors apply it in practice, this piece on restaurant stock valuation versus market cap walks through a real-world case. You can also run your own numbers in our Market Cap Calculator, which multiplies price by shares.
For the basics from scratch, our plain-English guide to market capitalization covers size categories and why price alone says little about a company.
The float version swaps total shares for floating shares. In Investopedia’s wording, free-float market cap is share price multiplied by shares issued minus locked-in shares, and the result is smaller than full market cap.
Written out:
Float market cap = share price × (shares outstanding − restricted or locked-in shares)
Investopedia’s example uses a $100 share price, 125,000 total shares and 25,000 locked-in shares. That leaves 100,000 floating shares, so float market cap is $10 million. The full market cap of the same company would be 125,000 × $100, or $12.5 million. The $2.5 million difference is the value of the locked-in block.
Let’s stretch it with a made-up company, for illustration only:
| Step | Number |
|---|---|
| Share price | $50 |
| Shares outstanding | 200 million |
| Full market cap | $10 billion |
| Founders, insiders and a strategic holder | 60 million shares |
| Floating shares | 140 million |
| Float market cap | $7 billion |
| Float as a share of outstanding | 70% |
Same company, same price, two numbers: $10 billion and $7 billion. Neither is wrong. They answer different questions. The first says what the whole company is worth at the market price. The second says what the tradable portion is worth.
The float number shrinks whenever some issued shares are locked in or otherwise unavailable for trading, which is the pattern Investopedia describes. In practice, the usual reasons include:
S&P DJI’s float adjustment methodology gives a concrete list. Its excluded categories include disclosed officers and directors, private-equity and venture-capital firms, corporate cross-holdings, restricted shares, company-sponsored employee plans, associated foundations or family trusts, most government entities, sovereign wealth funds and disclosed individual holders of 5% or more, all spelled out in its float adjustment methodology.
That list shows how much judgment sits behind a simple-looking number. “Available to the public” is a classification, not a data point printed on a filing.
If an index weighted companies by full market cap, a firm with 70% of its shares locked away would count as if investors could buy all of it. Index funds that track it would then try to buy more shares than exist for trading.
S&P Dow Jones Indices solves this by weighting the S&P 500 by float-adjusted market cap: price multiplied by shares outstanding adjusted for public float. A larger float-adjusted cap means a bigger impact on the index, according to S&P DJI. The stated aim of the adjustment is to better reflect each stock’s role in the market.
The rationale is investability. Weighting only the shares estimated to be available to public-market investors cuts index exposure to companies with limited tradable supply, as the float adjustment methodology explains. It is not only a US habit: Investopedia reports that free-float methodology is used by major indexes including the S&P 500, MSCI World and the FTSE 100.
The same source links float to trading behavior. Larger floats are generally associated with lower volatility, and institutional investors can trade large positions with less price impact. A thin float does the opposite: a few orders can move the price a lot.
To see how cap-based weights play out in funds, read our market cap weighting explainer and four-step check. If you are curious how funds that ignore size behave, our note on equal weight ETFs covers the contrast.
No, and this is where careless comparisons go wrong. Two reputable sources can start from the same share count and still land on different float figures.
S&P DJI bases its adjustment on shares available to investors rather than total outstanding shares. It excludes holdings of publicly traded companies, government agencies and certain strategic shareholders, per its methodology document.
MSCI defines free float as the proportion of shares outstanding deemed available for purchase in public equity markets by international investors. It calculates free-float shares as total shares outstanding less holdings classified as non-free-float, and the free-float percentage is 100% minus the non-free-float percentage, according to its free float data methodology.
Notice the wording. S&P frames it around investors in general; MSCI frames it around international investors. The classification rules, ownership thresholds and update schedules also belong to each provider. So a “float” of 85% in one dataset and 80% in another is not necessarily an error.
Fully diluted cap is a third version that adds in options and convertibles. We cover how analysts verify it in this walkthrough on fully diluted market cap.
There is no single winner. Match the number to the job.
Use full market cap when you want to:
Use float market cap when you want to:
Look at both when you want to:
Most confusion about market cap comes from one word doing two jobs. When a reader sees a company ranked by “market cap,” they usually assume it reflects the shares they could buy. Often it reflects every share in existence. Neither is a flaw, but you should know which one you are looking at.
Our view is that the full figure is the right starting point for ranking and size, because it is simple, transparent and follows the price-times-shares logic anyone can check. Float is the right second step when your question is about trading, index impact or who really controls a company. Treat it as a lens you apply after the ranking, not a replacement for it.
We also think the definition should always be visible. When you look at any cap number, on our site or anywhere else, ask which shares are in it. That one habit prevents most bad comparisons, especially across sectors where insider and government ownership differs widely.
— MarketCapLens
MarketCapLens tracks more than 2,500 public companies, with prices refreshed several times a day. Start with our market cap rankings to see how the largest companies stack up, then plug your own share price and share count into the Market Cap Calculator to test how excluding a locked-in block changes the result. If you want to compare by industry, our sector rankings group companies by market cap and our guide to sector weightings shows how to read them.
It is smaller or equal. When some issued shares are locked in or otherwise unavailable for trading, float cap falls below full cap, as Investopedia notes. If every outstanding share is freely tradable, the two numbers match.
Multiply the share price by the number of floating shares, which is shares outstanding minus restricted or locked-in shares. With a $100 price and 100,000 floating shares, float cap is $10 million. You can test your own inputs in our Market Cap Calculator.
The S&P 500 is float-adjusted market-cap weighted, meaning price times shares outstanding adjusted for public float, per S&P Dow Jones Indices. Companies with larger float-adjusted caps have a bigger effect on the index.
Providers define “available for trading” differently. S&P DJI and MSCI each publish their own rules for which holders to exclude, as seen in the MSCI free float methodology and S&P’s. Share counts may also be updated at different times.
It can. Investopedia says larger floats are generally associated with lower volatility, so a smaller float tends to mean sharper price swings on the same trading volume. Check trading volume and the company’s filings before drawing conclusions.
For informational purposes only and is not investment advice. Do not rely on the facts, figures, ticker symbols, or other statements in this article — they may be incomplete, outdated, or incorrect, and we are not responsible for errors. See our disclaimer.