Three to six months of costs is the number everyone quotes, but it is a floor, not a finish line. What actually decides your reserve, and how to build one automatically without feeling the pinch.
Every owner wants a single number. Tell me how much to keep in the bank and I will stop worrying about it. I understand the wish. But the honest answer is that the number is different for you than it is for the business down the road, and pretending otherwise is how owners end up either broke or hoarding cash they should be putting to work.
So let me give you the starting figure everyone quotes, then the part they leave out, which is the part that actually matters.
The common rule of thumb is three to six months of core operating costs held in reserve. Core costs means the money that goes out whether or not you sell a thing this month. Wages, rent, software, insurance, loan repayments. Add those up, multiply by three at the low end and six at the high end, and you have your rough band.
That figure is a floor, not a finish line. It is where the conversation starts, not where it ends. The right number for your business sits somewhere in that range, or above it, depending on three things most owners never stop to weigh.
The first is how predictable your revenue is. A business on recurring contracts, money that lands the same way every month, can sit at the lower end. A business living on lumpy project work, big invoices with long gaps between them, needs to sit higher, because the quiet stretch between projects is exactly when a thin reserve kills you.
The second is your fixed cost base. The heavier your fixed costs, the more reserve you need, because those costs keep marching whether the work comes in or not. A lean operation can carry a smaller buffer than one with a large payroll and a long lease.
The third is how fast you could cut if you had to. An owner who can trim costs quickly needs less reserve than one locked into commitments that take months to unwind. Flexibility is its own form of buffer.
Owners resist holding a reserve because it feels like dead money sitting there doing nothing. That is the wrong way to see it. A cash reserve is not idle. Its job is to buy you time and, more importantly, to buy you good decisions.
The business with no reserve makes desperate choices. It takes the bad client, accepts the terrible payment terms, discounts in a panic, because it has to have the cash this week. The business with a reserve can say no. It can wait for the right deal. That freedom to choose well, rather than grab whatever is in front of you, is what the reserve is actually paying for.
Most home stress is money stress, and it starts at the office. An owner with a real buffer sleeps differently, and so does everyone at their dinner table.
You do not build a reserve by waiting for a spare lump of cash to appear, because it never does. You build it the way you build any habit, by making it automatic and small. Open a separate account the operating account cannot see. Every time money comes in, skim a fixed percentage into it before you get used to spending it. Five percent, ten if you can. Treat it like a bill you owe your future self.
The account is separate on purpose. Money you can see is money you will spend. Put the reserve somewhere slightly out of reach and let it compound quietly while you get on with running the business. Business is a marathon, not a sprint, and the reserve is what keeps you in the race when a bad quarter arrives, because one always does.
Work out your monthly core costs this week. Just the numbers that go out regardless of sales. Multiply by three. That is your minimum target. If you are nowhere near it, do not despair, and do not try to get there in a month. Start the automatic skim now, today, and let it build.
And know your runway at all times, the number of weeks you could survive if the income stopped. The reserve figure matters, but the habit of always knowing where you stand matters more. Revenue is vanity. Size is ego. A reserve in the bank is the quiet thing that keeps the doors open when the flashy numbers cannot.
A common guide is three to six months of core operating costs, the money that goes out regardless of sales. Businesses with lumpy or unpredictable revenue, heavy fixed costs, or slow-to-cut commitments should aim for the higher end or beyond.
No. A reserve is not idle money, it is decision-making freedom. It lets you say no to bad clients and poor terms instead of grabbing whatever cash is in front of you. That ability to choose well is what the reserve pays for.
Make it automatic and small. Open a separate account and skim a fixed percentage, even five percent, off every payment that comes in, before you get used to spending it. Consistency beats size. A small skim done every time will build faster than waiting for a spare lump of cash.
The habit of always knowing your runway matters most. The reserve target gives you something to aim for, but an owner who checks their runway weekly will catch trouble early, long before the reserve is the last line of defence.
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