Runway

How many months your company can keep operating before it runs out of money, at its current rate of spending.

Example

You have $50,000 in the bank, spend $8,000 a month and make $3,000 a month. Net burn is $5,000, so runway is about 10 months.

Runway is the single most important number a founder tracks. Everything else — hiring, fundraising, pricing — is decided against it.

Burn rate — How much cash the company spends per month. Gross burn is everything going out; net burn is what goes out after revenue comes in.
Net burn — Monthly cash out minus monthly cash in. The real rate at which your bank balance falls.
Cash flow — The actual movement of money in and out of your bank account, as distinct from revenue you have earned but not been paid.
Default alive — The company reaches profitability on the money it already has, assuming current growth and spending. Default dead means it does not.

Debt and non-dilutive funding — Venture debt, revenue-based financing, grants and invoice finance. Money that does not cost equity — and does cost something else. (12 min)
Producing your own P&L and cash view — Turning categorised transactions into the two reports you will actually use, and the six numbers you should be able to recite from memory. (14 min)
The monthly reporting pack — Two pages, the same date every month, to investors and to yourself. What goes in it, what does not, and why the discipline outlives any single report. (11 min)
Uncertainty and rejection — Practical founder psychology, not therapy. Rejection is the job's raw material, and uncertainty never resolves — you get better at holding it. (10 min)
Sustaining yourself over years — This takes longer than you think. The founders who succeed are usually the ones still functioning in year four. (10 min)
Knowing when to change direction — Persistence and stubbornness look identical from the inside. Deciding in advance what would change your mind is the only reliable defence. (12 min)