Startup success is a race against your cash runway
Many aspiring founders plan their revenue projections carefully, but only roughly estimate the "operating fund" they need to survive before revenue kicks in. In reality, it takes an average of 3-6 months after opening to reach breakeven, and during that time fixed costs like rent, payroll, and utilities keep draining out regardless of sales. If your reserve fund runs short, you lose the ability to reinvest in marketing, and in the worst case, you run out of cash right before turning profitable and have to shut down.
This calculator adds up your monthly fixed and variable costs, multiplies by your target survival period, and adds a 15% buffer for unexpected situations to give you a final required amount. For example, a store with $3,000 in monthly fixed costs and $1,000 in variable costs needs a base fund of $24,000 to survive 6 months, plus a $3,600 buffer — about $27,600 total should be set aside in advance.
When planning startup capital, always keep this operating fund separate from your initial investment (equipment, buildout, interior). Spending everything on the initial investment and running short on operating funds is one of the most common reasons businesses fail, so when using loans or government startup funding, make sure to secure this operating fund as a distinct line item.
Frequently Asked Questions
Most new stores and businesses take an average of 3-6 months to reach breakeven. Six months is a reasonable minimum buffer to keep the business running even if revenue falls short of target during that time.
Setting aside an additional 10-20% of the calculated requirement is a safe practice to cover unexpected equipment failures, marketing overspend, or delayed revenue ramp-up.
A common approach is to apply your industry's average variable-cost-to-revenue ratio (materials, card fees, etc.) to your projected revenue, or reference published P&L data from similar franchise businesses.