Three to six months of operating expenses is the standard guideline. That range gives you enough cushion to cover payroll, rent, and other fixed costs if revenue drops suddenly or a major customer delays payment. But the right number for your business depends on factors specific to how you operate.

Seasonal businesses need more reserve than businesses with steady year-round revenue. A construction company in New Jersey that slows down in winter needs enough cash to cover the lean months without scrambling. A business with predictable recurring revenue can operate with less cushion. Revenue concentration matters too. If one or two clients make up most of your income, you need more reserve in case those relationships end unexpectedly.

Start by calculating your fixed monthly costs. Rent, payroll, insurance, loan payments, and any other expenses that hit regardless of revenue. That baseline tells you what it costs to keep the doors open when no money is coming in. Multiply that by three for a minimum target and six for a comfortable cushion.

The rule of thumb gets you started, but the actual target should come from budgeting and cash flow forecasting specific to your business. When you project revenue and expenses month by month, you can see where the gaps appear and size your reserve to cover them.

How quickly you can access other funding affects the calculation. A business with a line of credit already in place doesn’t need as much cash sitting idle. But credit lines can disappear when lenders get nervous, often exactly when you need them most. They should supplement reserves, not replace them.

Building reserves takes time. Most small business owners set aside a percentage of revenue each month until they hit their target. Even 5% adds up. The goal is to build the cushion when business is good so it’s there when things get tight.

Once you’ve built a comfortable reserve, consider keeping some in a high-yield savings account where it earns interest but stays accessible within a day or two. Having a plan and sticking to it matters more than hitting the perfect number. Fractional CFO and advisory services for small businesses can help you figure out the right target for your situation and create a path to get there.