Cash Flow, Runway & Burn Rate

Here is one of the most counterintuitive truths in finance: a company can be profitable on paper and still go broke. Profit and cash look like the same thing, but they answer different questions, and the gap between them has killed plenty of businesses that looked healthy in a P&L. This module untangles the two, then introduces the two words every startup and finance team lives by — burn rate and runway.

Profit is an opinion; cash is a fact

Profit is what’s left after you subtract costs from revenue for a period — but accounting counts a sale as revenue when it’s made, not when the money actually arrives. Cash is the money literally in the bank right now. Those two can drift far apart.

Imagine you land a $100,000 order in March, deliver it, and book the profit. But the customer pays in June. On paper, March looks great. In reality, you spent money on materials and wages in March and won’t see a cent until June. If payroll is due in April, that paper profit doesn’t help — you need cash. Growing companies fail this way constantly: the faster they grow, the more they pay out upfront while waiting to get paid.

Burn rate: how fast the cash drains

Burn rate is how much cash a company spends beyond what it brings in, per month. If you’re spending $500,000 a month and earning $300,000, your net burn is $200,000 a month — that’s the hole you’re filling from the bank each month. A company that’s spending more than it earns is “burning cash,” and the rate is the speed of the drain.

Burn isn’t automatically bad. A young company deliberately burns investor money to grow. What matters is the second number.

Runway: how long until the tank is empty

Runway is how many months of cash you have left at the current burn rate:

runway = cash in the bank ÷ monthly net burn

$2,000,000 in the bank, burning $200,000 a month, gives you 10 months of runway. Runway is the single most important number for an unprofitable company, because it’s a countdown: when it hits zero, you either raised more money, got acquired, or shut down. This is exactly why you see companies cut costs suddenly and hard — a shrinking runway forces the issue. Reducing burn extends runway, buying time to reach profitability. (When a whole company shifts into this mode, that’s the efficiency era in action.)

Remember: profit tells you if the business model works over time; cash and runway tell you if the business survives until then. You need both. A great model with no runway never gets to prove itself.

Cash or profit?

Tap each card to see which concept it describes.

Sort the statement

Drag each item into what it really describes — or tap an item, then a bucket.

How to use it

When a company suddenly slashes costs despite looking fine, cash is usually the reason — the runway got short and burn had to come down. In your own work, the sharp questions are: “Is that profit already in cash, or are we waiting on payment?” and “What’s our runway?” If you ever manage a budget, remember that timing matters as much as totals — a profitable plan that runs out of cash in month eight never reaches month nine. Cash is the oxygen; profit is the fitness. You need to keep breathing long enough for the fitness to matter.