What is cash runway, and why it matters more than your bank balance

A bank balance tells you what you have today. It does not tell you how long that money lasts at the rate you are spending it. That second number is your cash runway, and it is usually the more useful one.

What runway actually measures

Runway is the number of days your current cash covers your net outflows. If you have $9,000 on hand and you spend $300 more than you earn each day, your runway is 30 days. The arithmetic is not the interesting part. The framing is.

A balance is a snapshot. Runway is a forecast that takes both sides of your ledger into account: what is coming in, what is going out, and when. It changes every time you book a client, pay a contractor, or remember a recurring charge you forgot to cancel.

Why bank balance alone misleads you

Two freelancers can hold the same $9,000 and be in very different positions.

• One has $4,500 of monthly fixed costs and no signed work for next month. Runway: about 60 days, and shrinking.
• The other has $1,500 of monthly fixed costs and an invoice landing in two weeks. Runway: comfortably past 90 days.

The balance is the same. The decision space is not. If you only watch the balance, you treat both situations the same way, and you will under- or over-react in at least one of them.

How to estimate yours in five minutes

You do not need a model to get a useful first number. You need three inputs:

1. Cash on hand. Add the balances of the accounts you would actually draw from. Savings counts. Retirement does not.
2. Average daily outflow. Take the last 30 days of outflows and divide by 30. Use 60 if last month was unusually quiet or busy.
3. Average daily inflow. Same exercise, in the other direction. If your income is irregular, only count inflows you have a real reason to expect again.

Runway is cash on hand / (daily outflow − daily inflow). If inflows exceed outflows, your runway is effectively open-ended at the current pace, which is a different problem worth knowing about.

A concrete example

Say you have $12,000 across checking and savings. Last month you spent $5,400 and earned $3,000. Your net daily outflow is about $80.

That gives you a 150-day runway, give or take. Now imagine you forgot a $1,200 annual subscription that renews next week. Subtract it. The new runway is 135 days. Still fine, but the gap between "I have $12,000" and "I have about four and a half months at this pace" is the gap between a snapshot and a decision.

What to do with the number

Runway is most useful at three thresholds.

• Above 180 days. You can afford to think in quarters. Plan investments, not cuts.
• Between 60 and 180 days. You should be looking at the next two months in detail and re-running the number monthly. Most small operating decisions live here.
• Under 60 days. Treat the number as the headline metric. Re-run it weekly. New commitments need to clear a higher bar.

These thresholds are guides, not rules. The point is that runway sorts your situation into roughly the right mode of attention.

What runway does not tell you

Runway flattens timing. A 90-day average runway can still hide a shortfall in week three if a large bill lands before a slow month. This is why a forecast that walks day by day, like the projection in Vitsis, is more useful than a single average. The number gives you the headline; the day-by-day projection tells you whether the path is smooth.

Takeaway

Look at your balance to know what you have. Look at your runway to know what to do. They are different questions, and the second one is usually the one you need to answer.