Estimate how long your cash lasts
Enter the cash available now, expected monthly cash inflow, and expected monthly cash outflow. Use a consistent currency and include the cash movements relevant to your planning question. Inflow means cash arriving during a typical month, while outflow means cash paid out. The calculator shows monthly net burn and, when burn is positive, the number of months the starting cash would cover at that same rate. The accompanying line is a simplified illustration.
Runway formula
Monthly net burn = monthly outflow − monthly inflow. When net burn is positive, runway in months = cash available ÷ monthly net burn. A result such as 2.5 months is an arithmetic estimate based on equal monthly flows, not a calendar date or a claim that all payments arrive smoothly. The displayed monthly operating contribution is inflow minus outflow. It is a cash-flow figure, not accounting profit.
Checked example
Suppose a business has $120,000 in cash, receives $15,000 each month, and pays $35,000 each month. Net burn is $35,000 − $15,000 = $20,000 per month. Runway is $120,000 ÷ $20,000 = 6 months. The monthly operating contribution is −$20,000. Under the constant-flow assumption, six months of net burn uses the full starting cash. If the cash balance were zero while burn remained positive, the calculator would show zero months.
Important assumptions
The estimate assumes cash available and the inflow and outflow rates entered are accurate, and that those monthly rates stay constant. It does not predict hiring, seasonal receipts, delayed payments, debt maturities, tax dates, new funding, or a change in demand. If inflow equals or exceeds outflow, the tool reports no net burn rather than a finite runway. That does not guarantee the business has unlimited time: a future change in cash flows may reverse the result. Inputs must be finite and cannot be negative.
Review this estimate alongside the break-even calculator for unit sales and costs. For a single investment outcome rather than monthly cash survival, use the ROI calculator.
Frequently asked questions
What if monthly inflow is greater than outflow?
The current inputs show no net burn, so the formula has no finite depletion time. Recalculate if those monthly amounts change.
Is 2.5 months a precise date?
No. It is a ratio of cash to monthly net burn. The timing of individual bills and receipts can change the actual depletion date.
Is net burn the same as accounting loss?
No. This tool uses cash moving in and out. Accounting profit can differ because of non-cash items and when transactions are recognized.
Method and worked example checked against the calculator implementation. About our methods · Report a correction