How it works
Runway is the bluntest measure of financial security: if income stopped tomorrow, how many months could you pay for essentials without borrowing? The calculator divides liquid savings — cash and savings accounts you can reach within days, not retirement accounts or anything you would have to sell — by monthly essential expenses: housing, utilities, food, transport, insurance and minimum debt payments. The answer is months of survival, and the benchmarks map to real risk. Under one month is fragile: a single car repair becomes credit card debt. One to three months covers most ordinary emergencies — the appliance, the dental bill, the flight home. Three to six months covers a typical job search, which is why six months is the standard target the tool measures your shortfall against. Beyond six months makes sense for single-income households, commission earners and anyone in a shrinking industry. The output that changes behaviour is the shortfall — the dollar gap between your savings and six months of essentials. That is a concrete savings goal, and it is almost always smaller than people fear, because essentials exclude the discretionary spending that fills a normal month. Build runway in layers: one month fast, then three, then six, and keep it in a high-yield savings account where boredom is the point.
Formula
Runway = liquid savings / monthly essentials | Shortfall = 6 x essentials - savings
Tips
- Strip discretionary spending from the denominator — essentials only, and the target shrinks.
- Build in layers: one month fast, then three, then six.
- Keep the fund in a high-yield savings account, separate from daily checking.
- Do not invest the emergency fund; the bad month is when markets are down.
- Recalculate when essentials change — a move or a new child moves the target.
Frequently asked questions
- How do I calculate my financial runway?
- Divide liquid savings by monthly essential expenses. Liquid means cash and savings accounts you can reach within days — not retirement accounts, investments you would have to sell, or home equity. Essentials means the budget with discretionary spending stripped out: housing, utilities, food, transport, insurance and minimum debt payments.
- How many months of runway should I have?
- Three to six months of essentials is the standard target. Under one month is fragile — a single car repair becomes debt. Three months covers most ordinary emergencies; six covers a typical job search. Single-income households, commission earners and anyone in a shrinking industry should aim beyond six.
- What counts as essential expenses?
- What you must pay to keep the household running: housing, utilities, groceries (not restaurants), transport to work, insurance premiums, minimum debt payments and essential childcare. Streaming, dining out, vacations and hobbies pause in a real emergency, so they do not belong in the denominator.
- Where should I keep my emergency fund?
- A high-yield savings account — separate from your daily checking so it is not casually spent, but reachable within a day or two. It should not be invested: the fund's job is to be there in the bad month, and the bad month is precisely when markets are down.
- Should I build runway or pay off debt first?
- A small runway first — one month of essentials — so the next surprise does not go on a card. Then attack high-interest debt, which is usually the expensive emergency you are already in. Then finish the fund to three to six months before extra investing.