Fixed, Variable, and Knowing Your Floor

Your 'floor' is the smallest number your life can run on for a month. Most people have never calculated it, which is why job loss feels like free fall instead of a math problem.

Last verified 2026-07-16

Two ways an expense can behave

Fixed costs are the same every month — rent, insurance premiums, loan payments. They're easy to predict and hard to change quickly, because changing them usually means breaking a contract or moving.

Variable costs move month to month — groceries, fuel, going out. They're hard to predict and easy to change fast, which makes them the only lever you have in a bad month.

Your floor is a third number built from both: the total monthly cost of essentials only, with every want stripped out. It's your survival number, and most people have never calculated it.

Why two identical budgets aren't equally safe

Two people can spend exactly the same amount each month and have completely different exposure if income stops.

The one whose spending is mostly fixed has almost nothing to cut — the money is committed before the month starts. The one with more variable spending can shrink their outflow fast. Same total, very different resilience.

This is why 'how much do you spend?' is an incomplete question. The follow-up is: how much of that could you stop spending next month if you had to?

The floor is what sizes your emergency fund

The common advice is three to six months of expenses. The word doing the work there is which expenses.

It's three to six months of your floor — essentials only — not of your normal spending. In a genuine emergency you aren't funding vacations and restaurant meals; you're covering rent, utilities, food, insurance, transport, and minimum debt payments.

Sizing the fund off normal spending produces a target so large that people give up before starting. Sizing it off the floor produces a number that's actually reachable, which matters more than precision.