Inputs
Keep it simple: net income per month, all-in monthly spend, and total liquid assets.
Sum of bank, liquid funds, short FDs you can tap quickly.
100 = job loss
Applied in month 1
Monthly burn after shock
—
Expenses × (1+surge) − Income × (1−drop)
Runway
—
If burn ≤ 0: you’re saving (no depletion)
Assets usable now
—
= Max(assets − shock, 0)
Projected leftover after horizon
—
At constant burn for the horizon
Rule of thumb
Target at least 3–6 months of runway. Under stress, cut discretionary spend first and rebuild the cushion once income stabilizes.
Examples