The short answer: Free cash flow for startups is operating cash flow minus capital expenditures, including capitalized software. It differs from net burn because burn also counts financing outflows such as debt principal. In an illustrative example, free cash flow of −$155,083 a month sits beside a net burn of −$185,083.
- Free cash flow measures what the business generates; net burn measures how fast the bank balance falls.
- Leaving capitalized software out of capex flattered the example company’s free cash flow by $540,000 a year.
- Runway must be computed on net burn. Using free cash flow overstated runway by 4.3 months in the example.
- Free cash flow is a non-GAAP measure, so the formula should be written down and applied the same way every quarter.
Last updated November 2026.
Free cash flow is the cash a company produces from operations after paying for the assets that keep it running. For a startup, that number is usually negative, and its size against revenue is what investors read as capital efficiency.
Net burn answers a narrower question: how much cash leaves the account each month. The two figures share most of their inputs, so founders often treat them as one number. They are not, and the gap between them can change a runway forecast by several months. For the burn calculation itself, see how to calculate burn rate and runway.
What is free cash flow for startups?
Free cash flow is operating cash flow minus capital expenditures. Both inputs come straight from the statement of cash flows, which makes the measure hard to dress up when it is defined consistently.
Under the indirect method, operating cash flow starts with net income and reverses non-cash items. Depreciation, amortization, and stock-based compensation are added back, and changes in working capital are layered in. Capital expenditures then come out: equipment, leasehold improvements, and, for most software companies, capitalized development costs.
The formula is short. The judgment sits in the definitions. Free cash flow does not appear in GAAP, and it meets the SEC’s test for a non-GAAP measure under Regulation G, which covers any measure of cash flows that:
“Excludes amounts, or is subject to adjustments that have the effect of excluding amounts, that are included in the most directly comparable measure calculated and presented in accordance with GAAP” (17 CFR 244.101)
Regulation G binds public registrants, and a private startup is not one. The principle still applies to a board deck: name the GAAP measure underneath, show the bridge, and hold the definition steady.
How is free cash flow different from net burn?
Free cash flow stops before financing activities, while net burn captures every outflow except new equity. The difference is mostly debt service and other financing payments.
Venture debt makes the gap concrete. Interest paid sits in operating activities under US GAAP, so it already reduces free cash flow. Principal repayments sit in financing activities, so they reduce the bank balance without touching free cash flow. A company amortizing a $1.8M term loan over 60 months pays $30,000 of principal every month that free cash flow never shows.
| Item | Free cash flow | Net burn |
|---|---|---|
| Payroll, rent, vendors | Included | Included |
| Interest on venture debt | Included (operating) | Included |
| Equipment and capitalized software | Included (capex) | Included |
| Debt principal repayments | Excluded (financing) | Included |
| Finance lease principal | Excluded (financing) | Included |
| Equity raised | Excluded | Excluded |
| Best used for | Efficiency and valuation | Runway and survival |
The practical rule follows from the table. Use net burn for the zero-cash date. Use free cash flow when comparing efficiency across periods or against peers. The runway scenario planning guide shows how burn feeds base and downside cases.
How do capitalized software costs change free cash flow?
They can move hundreds of thousands of dollars out of operating cash flow and into investing activities. Free cash flow catches that shift only if capex includes them.
Under ASC 350-40, a company capitalizes qualifying internal-use software costs instead of expensing them. Engineering salaries that meet the criteria become an asset on the balance sheet. The cash payments then typically appear under investing activities, so operating cash flow improves even though the same engineers were paid the same amount.
A free cash flow figure built only from equipment purchases misses this entirely. That is the most common way startup free cash flow gets flattered. In the example below, excluding $540,000 of capitalized software would have improved reported free cash flow by 29.0% (from −$1,861,000 to −$1,321,000) with no change in cash. Ask any provider or analyst to state which capex lines the formula includes.
Worked example: free cash flow and net burn for one company
Consider an illustrative SaaS company with $6.2M in ending ARR and $5,480,000 of revenue over the trailing 12 months. It holds $4,100,000 in cash and is repaying a venture loan.
| Line (trailing 12 months) | Calculation | Amount |
|---|---|---|
| Net income | From the income statement | −$2,140,000 |
| Add back non-cash items | $185,000 D&A + $310,000 stock compensation | +$495,000 |
| Working capital change | Mostly deferred revenue from annual prepayments | +$420,000 |
| Operating cash flow | −$2,140,000 + $495,000 + $420,000 | −$1,225,000 |
| Capital expenditures | $96,000 equipment + $540,000 capitalized software | −$636,000 |
| Free cash flow | −$1,225,000 − $636,000 | −$1,861,000 |
| Debt principal repaid | Financing activities | −$360,000 |
| Net burn | −$1,861,000 − $360,000 | −$2,221,000 |
Monthly, free cash flow is −$1,861,000 ÷ 12 = −$155,083, and net burn is −$2,221,000 ÷ 12 = −$185,083. Runway on net burn is $4,100,000 ÷ $185,083 = 22.2 months. Dividing by free cash flow instead gives 26.4 months, an overstatement of 4.3 months.
Two inputs also deserve a second look. The $420,000 working capital benefit comes from customers prepaying annual contracts, and it reverses if billing moves to monthly. Free cash flow margin is −$1,861,000 ÷ $5,480,000 = −34.0%. The company, loan, and balances are illustrative.
When do investors start asking about free cash flow instead of burn?
Usually once a company approaches breakeven or raises growth-stage capital. Before then, runway dominates the conversation, and burn is the number that answers it.
At Series B and later, investors increasingly frame efficiency through free cash flow margin. A common SaaS heuristic, the Rule of 40, adds revenue growth to a profit margin, often free cash flow margin, and looks for a sum at or above 40. The example company growing revenue 62% a year scores 62 − 34.0 = 28.0, which would prompt questions about spend efficiency. The SaaS cash flow strategy guide covers how annual prepayments shift that score.
Free cash flow also becomes the base of valuation work. A discounted cash flow model projects it forward, as the guide to forecasting free cash flow for a DCF explains. A forecast built on an inconsistent historical definition carries that error into every projected year.
Is free cash flow or EBITDA the better efficiency measure for SaaS?
Free cash flow, for most startups, because it records the cash actually spent. EBITDA leaves out capitalized software, working capital, and, in adjusted form, stock compensation.
In the example, EBITDA is −$2,140,000 + $185,000 D&A + $198,000 interest = −$1,757,000. Adding back stock compensation gives adjusted EBITDA of −$1,447,000, which looks $414,000 better than free cash flow. The gap would widen in a year with heavy capitalization and narrow in a year with large prepayments.
EBITDA still has a place in lender covenants and in comparisons with mature peers. For a company spending outside capital, the question is how much cash the model consumes, and free cash flow answers it directly. Aaron Ressel and the senior team at Debit & Co. reconcile both measures to the cash flow statement each close, which keeps the bridge auditable. For the statement itself, see how to read a startup cash flow statement.
Frequently asked questions
What is free cash flow?
Free cash flow is operating cash flow minus capital expenditures, including capitalized software. It shows the cash a business generates or consumes after paying for the assets it needs to operate, before any financing.
How is free cash flow different from net burn?
Net burn includes financing outflows such as debt principal and finance lease payments, while free cash flow excludes them. Use net burn to calculate runway and free cash flow to judge efficiency.
How do capitalized software costs change FCF?
Capitalized development costs typically move from operating to investing activities, which raises operating cash flow. Free cash flow stays accurate only if capital expenditures include those software costs.
When do investors start asking about FCF instead of burn?
Usually as a company nears breakeven or raises growth-stage capital. Investors then compare free cash flow margin with revenue growth, often through the Rule of 40.
Is FCF or EBITDA the better efficiency measure for SaaS?
Free cash flow is usually better for startups because it captures capitalized software, working capital swings, and interest actually paid. EBITDA remains useful for lender covenants and mature-company comparisons.
Sources: 17 CFR 244.101 (Regulation G), via eCFR; FASB Accounting Standards Codification Topics 230 (Statement of Cash Flows) and 350-40 (Internal-Use Software). The company, loan, balances, and growth rate are illustrative.
