Savings runway calculator — how long will your savings last?
How long would your savings really last if you left? The quick sum is savings divided by essential costs. Here is that number, and then the honest version: the same savings run through 5,000 simulated futures in which the new income arrives after a gap, and swings once it does.
The quick sum, and why it flatters
That figure is the floor, not the forecast. Almost nobody quits into zero income for ever: the move usually brings a new salary after a start date, or freelance income that ramps up and swings. In the worked example the new income is £2,200 a month after a ramp of 6 months with 30% month-to-month volatility, against essential costs of £2,400. Across 5,000 futures the buffer stays above zero for twelve months in 60–70% of them; one future in ten had run out by month 9. The model forecasts only that question — whether your buffer survives the transition — and not whether the job, the clients or the business turn up. The career-change guide explains why it refuses the second question.
Run it on your figures
PROBABLY SURVIVABLE, WATCH THE RAMP
60–70%
probability the balance stays above zero over 12 months, across 5,000 simulated futures
- Months before the buffer runs out — 1 in 10 futures
- 9
- Median future
- 12+
- Best 1 in 10
- 12+
- Scenarios — Expected
- Expected 64%
- Upside
- Upside 98%
- Downside
- Downside 0%
- Stress
- Stress 0%
- What moves it most
- Essential monthly costs
- Where the odds flip
- A confirmed income source at or above £2,124/month moves the median path to survival.
- Evidence quality
- moderate
Seed 564 · receipt cr_a61c7158_234 · career@1.1.1. Same figures, same seed, same answer — reproduce it or verify the receipt.
Worked example, computed by the engine at build time. Edit the figures and it recomputes here, in your browser.
The engine runs free for one person, with no account, on LEXUN for individuals; the receipt beside the result lets you, or anyone you show it to, re-run the same figures and get the same answer. Saving the decision to a record — so it can be scored against what actually happens — needs a LEXUN Key, a passcode that locks the record on your device. The business-side sibling of this page is the cash runway calculator; the same monthly maths for a company, with the formula beside the odds. Not sure whether your role is the thing at risk? The Labs check is my role exposed to automation? looks at the task mix, not the job title.
Questions people ask
How do I work out how long my savings will last if I quit?
The plain version is savings divided by essential monthly costs: £9,000 of savings against £2,400 a month lasts a little under four months with no income at all. The real question includes the income that arrives after a gap, how long the gap is, and how much that income swings.
Can it tell me whether I will get the job or the clients?
No, and it says so. There is no defensible base rate for whether a career move works out. It forecasts only the resolvable question: does your buffer survive the transition?
Is it private?
Yes. The figures you type stay in your browser: this page has no Copilot box, so nothing you type here is sent to a server. There is no account and no card.
Why is the answer a range and not a date?
Because income after a change is uncertain. Across 5,000 simulated futures with that uncertainty included, the model reports the probability your buffer stays above zero over the horizon, plus the month by which one future in ten had run out.