Net income is an estimate written under accounting rules. Free cash flow answers a blunter question: after the business bought what it had to buy, what cash is actually sitting there?
That distinction matters more than almost any other number on a financial page, because profits can be created by judgement while cash can only be created by customers. A company can report rising earnings for years and still run out of money – at which point it doesn’t matter how profitable it looked on paper. The income statement tells you what accountants concluded; this tells you what left the bank account.
The calculation
Free cash flow = operating cash flow − capital expenditures
Operating cash flow comes from the cash flow statement, first section. It starts from net income and adds back charges that never involved writing a cheque – mainly depreciation, the accounting spread-out of equipment bought long ago – then adjusts for timing changes such as inventory building up or customers paying slower.
Capital expenditures (“capex”, listed as purchases of property, plant and equipment) come from the investing section. This is money spent on things that last: buildings, machines, warehouses, servers, vehicles, tools.
What remains is theoretically available without anyone deciding to sell shares or borrow: pay a dividend, buy back stock, repay debt, acquire something, or hold as a cushion. That is why serious investors watch it religiously – it is the pool every other promise gets paid out of.
Work it with small numbers
Illustrative figures, so you can check each step yourself.
| Line | Amount | Note |
|---|---|---|
| Revenue | $40,000 | Sales billed for the year |
| Net income | $12,000 | From the income statement |
| Add back depreciation | $5,000 | No cheque was written this year for it |
| Inventory built up | −$3,000 | Cash went into stock sitting on shelves |
| Operating cash flow | $14,000 | Actual cash from trading |
| Capital expenditures | −$9,000 | New oven and delivery bike |
| Free cash flow | $5,000 | Genuinely discretionary money |
Notice the two places this diverges from the $12,000 profit figure. Depreciation pushed cash above profit; the inventory purchase pulled it below. Net margin told one story, cash generation told another, and both were honest – they measure different things.
Cash flow margin is the comparison worth making across companies: free cash flow ÷ revenue. At $5,000 of free cash flow on $40,000 of sales the business converts about 12.5% of revenue into spendable cash. Compare two firms with identical net margins and very different cash conversion and you’re usually looking at a difference in how much machinery the business needs to exist – or in how much unpaid inventory it’s accumulating.
Why the same number means opposite things at different companies
Apple is the flattering case: for years it has thrown off cash far beyond what it needed to spend running its supply chain, which is exactly what funded enormous share buybacks and a dividend. Precise figures move every quarter, so pull them from its own filings instead of trusting an article – the cash flow statement in the 10-K has both lines side by side.
Amazon is the instructive counter-example. In several past years its reported free cash flow hovered near zero or went negative even as revenue exploded, because every new warehouse and every rack of servers cost more than the business threw off that year. Reading only “negative free cash flow” would have been a disastrous conclusion. Reading the reason – spending that produced faster growth – is the entire skill.
So the sign of the number tells you almost nothing alone. Four things change the interpretation:
- Growth versus decay. Negative free cash flow alongside fast revenue growth is usually investment. Negative free cash flow alongside flat or falling revenue is a leak. Both look identical on one line.
- Maintenance versus expansion. Ask whether capex merely keeps the lights on or buys new capacity. A company whose “maintenance” spending already consumes all its cash has no spare room to grow without borrowing.
- Whether the spending produced anything. Give it a few years. Capex that turns into higher sales and margins was good spending; capex into lower returns was an expensive mistake discovered late.
- The trend, not the quarter. Free cash flow lumpy with one heavy-investment year is normal. Four straight disappointing years is the business.
Two ways this number lies to you
Companies don’t usually falsify cash; they time it. Watching for these two habits is enough to catch most misleading presentations:
Deferring maintenance. Free cash flow improves beautifully when you postpone replacing worn-out equipment – you borrowed the improvement from the future, and it arrives with interest. If capex drops sharply while management says nothing about it, ask what got postponed. Airlines, factories and telecoms are where this shows up most.
Stretching suppliers. Pay vendors slower and your operating cash flow rises this quarter without selling anything extra. It’s legal, sometimes clever, and it reverses the moment suppliers demand payment. A rising payables balance in the working-capital adjustments is the tell.
A quick sanity habit: compare cumulative free cash flow to cumulative net income over three to five years. They should broadly track. A company reporting healthy profits forever while producing no cash is being paid in something other than money – often receivables it hasn’t collected or inventory nobody ordered. Follow that gap into the balance sheet and see where the supposed earnings parked themselves.
Full context, including management’s explanation of what the money was spent on, sits in the annual report – specifically the management-discussion section, where a CFO has to explain capex plans in words rather than just numbers. If a company won’t explain why it’s spending, that silence is information too.
This is an explanation of how to read a financial statement, not investment advice or a recommendation about any company mentioned – the examples describe historical patterns rather than current figures, so take numbers from the filings themselves, and any security can lose value regardless of how much cash it generates.