The Quit My Job Runway Calculator

The Runway Number

Runway is the number of months savings can carry living costs with no salary arriving. It is one division: what is genuinely spendable, divided by what leaves each month after any income that is already coming in. This calculator does that division and shows the two figures underneath it, so the number can be checked rather than taken on trust.

What Runway Is Enough?

No figure is right for everyone, and this calculator takes no view on it. What the number depends on is concrete: what the monthly gap actually is, whether any income is already landing, and how long the new income is likely to take to arrive. Those last two are guesses, which is the honest limit of any runway figure.

Self-employment is far more common in some economies than others, and the World Bank series on self-employment as a share of total employment shows how wide that variation runs. The norms that surround the decision differ with it.

The Expenses People Forget to Count

Monthly costs usually change on leaving employment rather than staying put. Health cover previously carried by an employer, professional subscriptions, equipment, and tax that used to be deducted at source all become direct outgoings, and tax in particular tends to arrive as a lump rather than monthly.

Irregular costs are the other gap. Annual renewals, quarterly bills and anything seasonal do not show up in a typical month, so a figure taken from one month understates the burn. Dividing the yearly total by twelve and folding it in gives a monthly figure the runway can actually be built on.

Why Keeping a Reserve Matters

The reserve field exists so the runway figure counts only money that would genuinely be spent down. Savings set aside for a real emergency are not runway, and including them inflates the number by exactly their size divided by the monthly burn. At the defaults, the 5,000 reserve is worth 2.5 months of runway that the tool deliberately does not count. Setting a reserve at or above total savings leaves nothing to draw on, and the tool reports zero months rather than a negative figure.

The default scenario, worked through

Take 30,000 of accessible savings, 2,500 a month of living costs, 500 a month of expected side income, and 5,000 held back as a reserve. Usable savings are 25,000 and the monthly burn is 2,000, so the runway is 12.5 months. Those defaults are a starting point for seeing the arithmetic rather than a suggested plan.

Where side income matches or exceeds expenses, there is no burn and nothing is being drawn down. The tool reports that as "Not depleting" rather than a number, because no finite month count describes it. Just short of that point the division still works but the answer stops being useful: a gap of 1 a month against 25,000 of usable savings returns 25,000 months, which is arithmetically right and practically meaningless. Figures far beyond a few years are describing an assumption of a permanently fixed gap rather than anything that could be planned around.

What moves the runway most

Monthly expenses dominate. A 1% increase adds 25 to the monthly gap and shortens the runway by 1.23%, against 1.20% for a 1% cut in savings, 0.25% for a 1% rise in side income, and 0.20% for a 1% rise in the reserve. Expenses and the reserve both pull the same way: raising either shortens the runway.

The useful consequence is that expenses and side income are interchangeable at the margin, because only their difference enters the calculation. Cutting 100 from monthly costs and earning 100 more each month produce the same answer, 13.2 months at the defaults. Whichever is easier to move is the one worth moving.

How the math works

Runway = (savings − reserve) ÷ (monthly expenses − side income). Usable savings and monthly burn are the two intermediate figures, both shown in the result. The model holds expenses and income flat for the whole period and applies no interest, inflation, tax or investment return, so it is a straight-line projection rather than a forecast. OpenStax's Entrepreneurship covers the cash-flow accounting this sits inside.