Income vs Lifestyle Runway
Income vs Lifestyle Runway Calculator
What this calculator does
This calculator answers the insolvency question: how long can you keep spending the way you do before the accounts run dry? It is the bridge between income and lifestyle.
The math, with a worked example
Monthly surplus or deficit = income − expenses. Months until broke = savings ÷ deficit. Months to 3-month emergency fund = (3 × expenses − savings) ÷ surplus. With $3,500 income, $3,900 expenses, and $1,200 savings, you burn $400 per month and hit zero in 3 months. Flip that to $4,000 income against $3,000 expenses and the $9,000 three-month emergency fund takes about 8 months to build from the same $1,200.
Why this matters
Runway is the one number that turns money panic into a schedule: income minus expenses, savings divided by the gap. Burning $400 a month against $1,200 of savings is 3 months — and 3 months is a deadline you can act on, where 'money is tight' is just weather.
Methodology and transparency
Deficit runway = savings ÷ (expenses − income); with a surplus, the same inputs give months to a 3-month emergency fund. The model burns savings linearly, and that's the assumption real crises break: spending has lumps (car repair, deductible, annual premium) and income shocks rarely arrive alone, so the true runway is usually shorter than the straight-line number. Treat the output as your best case, not your plan. Everything runs in your browser; no data is sent or stored.
Last reviewed: 2026-08-08
Common questions
What does insolvent mean here?
It means your expenses exceed your income. You are not out of money yet if you have savings, but you are on a countdown.
Should I include retirement contributions?
Include them as expenses if you would stop them in an emergency. Otherwise leave them out to see the core lifestyle gap. If you're considering the balance itself as runway, price it first — an early withdrawal can cut a $10,000 balance to about $6,800.
What if the runway is under 6 months?
Treat it as an emergency. Cut non-survival spending until income covers expenses. If cutting can't close the gap, the question stops being budgeting — check whether your income falls under your state's Chapter 7 median.