Ember & Oak, a full-service restaurant, holds $22,800 in cash against a monthly burn of $6,000, with everything in it: rent, gear, software and the owner draw. That's 3.8 months of runway at the current burn. That's under the four-month line, so it stays on the watchlist.
Runway = cash on hand ÷ monthly burn, using your heaviest recent burn month rather than your cheapest. The main runway guide has the full reasoning and what to do at each level, and the calculator runs it on your numbers in your browser.
The twist for restaurant owners
Restaurant burn is lumpy: rent and payroll are fixed but food cost rides revenue, so compute burn from your heaviest recent month. A slow January against December burn is how 3.8 months becomes 2 in practice.