Can you afford to quit your job - and how long will your money last?

Most runway calculators assume you have already jumped. This one is built for the month before: you still draw a salary, you have side income, and you want the earliest month you could resign and still be standing if your biggest client walks out with you. Nine numbers in, a 36-month cash path out.

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Your numbers

Everything you could actually spend. Exclude tax you already owe.
$
Rent, food, insurance - what you have to take out of the business each month.
$
Software, accountant, hosting, contractors.
$
What the business invoices now - contracted work, not hoped-for work.
$
Compounds every month, so it is the input that flatters hardest. Start at 0-1% and only raise it for growth you can name the source of.
%
Held back out of your runway, because it is not your money.
%
Take-home pay from the job you would leave. Enter 0 if you are already independent.
$
Used for the downside case: this client leaves the month you go full-time.
%
The cash you refuse to go below. "Safe" below means never dipping into it. Set 0 and "safe" means reaching exactly zero, which is the textbook definition and nobody's actual plan.
months

The answer

The four checks

    Spendable cash if you go full-time next month

    Base case Biggest client leaves Zero - out of money

    What this model assumes, in plain words

    • Costs stay flat. No inflation, no seasonality, no one-off purchases.
    • Tax is a flat percentage of profit. Real tax is banded and depends where you live.
    • You are paid in the month you invoice. Late-paying clients are not modelled.
    • Your growth rate compounds every month for all 36 and never stops. That is the assumption most likely to be wrong, which is why the example starts at 1%.
    • Tax set aside is held, never spent. Paying the bill earlier or later does not change the lines above - only the balance in your bank account.
    • A lost client is gone for good; the income that is left keeps growing at your growth rate.
    • "Earliest safe month to quit" means your spendable cash never goes below your safety buffer before month 36, after your biggest client leaves. Set the buffer to 0 and it means never going below zero. It says nothing about month 37, and the tile says so when that is all it is measuring.
    • "Runway" is always measured to zero, never to your buffer - that is what the word means everywhere else, so the buffer never quietly shortens the number you compare with someone else's calculator. The buffer moves the quit month and the client-loss check, and the tiles say which.
    • The lines carry on below zero. That shows how deep the hole gets, not that you could keep spending money you do not have.
    • This is arithmetic, not advice. It cannot know your contracts or your tax position.

    Not built yet - tell me which of these you would actually use

    • SOONSave scenarios side by side and compare them
    • SOONEnter what actually happened each month and see forecast vs actual
    • SOONTax modes: US quarterly estimates, UK Self Assessment, Hong Kong salaries and profits tax
    • SOONOne-page PDF for a partner, an accountant or a bank
    • SOONPer-client income lines, so concentration is measured rather than guessed