Market Capitalization Calculator

One multiplication, and a lot riding on it

Market capitalisation is the price of one share multiplied by the number of shares. That is the whole calculation.

What it produces is the market's current price tag for the entire company. If you wanted to buy every share at today's price, this is roughly what it would cost you, before anyone noticed you were buying and the price moved.

Two inputs, one answer, and no complexity in the arithmetic at all. Where the care is needed is in the second input, because there are several different share counts a company can quote and they give different answers. That, and knowing what this number deliberately does not include, which is the subject of the two sections below.

Two boxes

1. Price of a single share. The current market price.
2. Number of outstanding shares. How many shares exist.

Press Calculate and you get the market capitalisation.

Both figures come from the same places. The price from any market data source, and the share count from the company's most recent financial statements, usually on the cover page of the annual or quarterly filing, or from the exchange listing.

Use figures from close to the same date. Share counts change when companies issue new shares, buy their own back, or when employee options are exercised, so a price from today against a count from two years ago can be some way off.

Which share count you use changes the answer

The formula wants shares outstanding, and that phrase is more specific than it sounds. A company can put several different share numbers in front of you.

Shares outstanding is what you want. All shares currently held by everyone: institutions, the public, company insiders, the founding family.

Issued shares can be higher, because it may include treasury stock, which is shares the company has bought back and holds itself. Those are not outstanding, and a company does not own a piece of itself in any meaningful sense.

Authorised shares is the ceiling set in the company's constitution, the maximum it is permitted to issue. Frequently far above what actually exists. Using this gives you a badly inflated answer.

Diluted shares is higher again, counting shares that do not exist yet but could, if options and convertible instruments were exercised. Useful for thinking about what your stake might be worth later. Not the right number for what the company is priced at today.

Free float is lower, and it has its own section below because it is the one professional investors use most.

If a filing gives you a range of numbers, the one on the cover page of a quarterly or annual report, stating shares outstanding as of a recent date, is the one to take.

Four companies

Look down the price column and then down the market cap column. They are not in the same order of usefulness at all.

The 150 share belongs to a company worth three hundred billion. The 2.40 share belongs to one worth sixty million, which is five thousand times smaller. But there is nothing in the prices themselves that tells you that, because a share price on its own is meaningless without knowing how many exist.

This is the most common misuse of a share price. A stock at 12 is not cheaper than one at 150 in any sense that matters. A company can perform a split, turn one share at 150 into ten at 15, and nothing whatsoever has changed about the business or its value. The market cap is identical the second before and the second after.

Which makes market cap the first number to look at when comparing two companies, and the share price close to the last.

The number the index funds actually use

There is a version of this calculation that matters more than the standard one for anyone whose money is in index funds, and it uses a smaller share count.

Free float counts only the shares genuinely available to trade. It strips out blocks that are locked away: a founding family's stake, a government holding, a parent company's controlling interest, shares held by insiders under restriction.

Take a company at 100 a share with a billion shares outstanding, where 40 percent is held by the founder and never traded.

• Full market capitalisation: 100,000,000,000
• Free float capitalisation: 60,000,000,000

Forty billion of difference, describing the same company on the same day.

Major stock indices weight their constituents by free float rather than by full market cap, and the reason is practical. An index fund has to be able to buy the shares it is supposed to hold. Weighting by shares that never come to market would force funds to chase stock that is not for sale.

So the consequence for a company with a large locked-up stake is that its influence on an index, and therefore the amount of index money that flows into it, is smaller than its headline size suggests. This tool gives you the full figure. To get the float version, enter the freely tradeable share count instead.

The thing market cap deliberately leaves out

Market capitalisation prices the equity. It says nothing at all about what the company owes.

Consider two companies, both with a market cap of a billion.

The first holds three hundred million in cash and has no debt. The second has eight hundred million of borrowings and almost no cash.

Anyone buying the whole of either would be taking on a very different situation. Buy the first and three hundred million of your purchase price comes straight back to you in cash. Buy the second and you inherit eight hundred million of obligations on top of what you paid.

The measure that captures this is enterprise value: market capitalisation, plus debt, minus cash. It answers what it would cost to acquire the business outright and clear its balance sheet, which is a fairer basis for comparing two companies with different financing.

Market cap is not trying to answer that question, and it is not wrong for failing to. It is the price of the equity, which is exactly what a shareholder owns. But when the comparison matters, and it usually does for anything capital intensive or heavily borrowed, the debt figure has to come into it. The net debt calculator gives you that piece.

Large, mid, small, and why the borders move

Market cap is how companies get sorted into size categories, and those categories drive real decisions. Fund mandates specify them, indices are built around them, and a great deal of money is only permitted to buy within a band.

The conventional US grouping runs roughly like this: large cap above ten billion, mid cap between two and ten billion, small cap between three hundred million and two billion, and micro cap below that.

Three cautions about those figures, and each one matters more than the numbers themselves.

They are conventions, not definitions. No authority sets them. Different index providers and fund managers draw the lines differently, and a company can be mid cap on one provider's list and large cap on another's.

They drift upward over time. A ten billion company was enormous three decades ago and is unremarkable now. Any fixed threshold slowly stops meaning what it meant when it was set.

They are entirely relative to a market. A large cap in Nepal, India, Britain and the United States are four different sizes of company. Applying US thresholds to a smaller exchange puts nearly everything on it in the small cap bucket, which tells you about the exchange rather than about the companies.

So use the bands as rough shorthand, and check what definition is being used whenever the label carries any weight.

Market cap is a price, not a valuation

One last distinction, and it is the one that stops this number being over-read.

Market capitalisation tells you what the market currently charges for a company. It does not tell you what the company is worth, and the entire practice of investing rests on those two things not always agreeing.

It also carries all the market's moods. Sentiment, momentum, the last set of results, an interest rate decision that had nothing to do with this business. A company can be a third smaller in September than it was in March without a single thing changing inside it.

And there is a mechanical caveat on the arithmetic. The figure assumes every share could be sold at the current price, which they could not. That price is what the last small parcel traded at. Try to sell a substantial holding and the price moves against you, which is why takeovers are agreed at a premium to market cap rather than at it.

So treat it as the market's current asking price for the equity, useful for comparison, for sizing, and for context. Then look at what the company earns, owns and owes before deciding whether the price is a good one.

Questions people ask

How is market capitalisation calculated?

Share price multiplied by the number of shares outstanding. At 150 a share with two billion shares, that is three hundred billion.

Which share count should I use?

Shares outstanding, from a recent filing. Not authorised shares, which is a permitted ceiling, and not fully diluted shares, which counts shares that do not yet exist.

Is a lower share price a cheaper company?

No. A share price on its own says nothing without the share count. A stock split turns one 150 share into ten 15 shares and changes nothing about the company or its market cap.

What is free float market cap?

The same calculation using only the shares genuinely available to trade, excluding locked-up holdings by founders, governments or parent companies. Major indices weight companies this way, so it is often the more relevant figure.

Does market cap include debt?

No. It prices the equity only. Enterprise value, which is market cap plus debt minus cash, is the measure that accounts for what a buyer would actually be taking on.

What counts as a large cap company?

Conventionally above ten billion in US terms, with mid cap from two to ten billion and small cap below that. These are conventions rather than definitions, they drift upward over time, and they mean different things on different exchanges.

Is market cap what the company is worth?

It is what the market currently prices it at, which is not the same thing. It moves with sentiment, and it assumes every share could be sold at the last traded price, which is why acquisitions are agreed above it.

Why does market cap change when the share count does?

Because it is one of the two inputs. Issuing new shares raises the count, buying shares back lowers it, and both change the total even when the price does not move.

References

Market capitalisation is the product of share price and shares outstanding, and enterprise value adds debt and subtracts cash to arrive at the cost of acquiring a business outright. The distinction between shares outstanding, issued shares including treasury stock, authorised shares and fully diluted shares follows standard corporate finance practice as set out by the Corporate Finance Institute. The convention of weighting index constituents by free float rather than full capitalisation, and the requirement that performance and holdings be capable of being replicated by investors, is reflected in the Global Investment Performance Standards published by CFA Institute. The treatment of gross profit and the underlying financial statements from which share counts are taken follows Internal Revenue Service small business guidance.

1. Corporate Finance Institute, Markup and Corporate Finance Resources. https://corporatefinanceinstitute.com/resources/accounting/markup/
2. CFA Institute, Overview of the Global Investment Performance Standards. https://www.cfainstitute.org/insights/professional-learning/refresher-readings/2026/overview-of-the-global-investment-performance-standards
3. Internal Revenue Service, Publication 334: Tax Guide for Small Business. https://www.irs.gov/publications/p334