What is a cash runway calculator?
A cash runway calculator estimates how long starting cash may last if monthly cash inflows, monthly cash outflows and optional one-time events stay close to the numbers you type. It is a cash-timing view. It is not a profit-and-loss forecast, a valuation, a loan decision or advice about whether the business should continue.
The result is an estimate from a simplified monthly scenario. Actual customers, costs, timing and events can differ, so a projected balance does not guarantee that cash will be there.
How to calculate cash runway
When monthly outflows exceed monthly inflows and you have not added one-time events, monthly net burn is the difference. Simple runway is starting cash divided by that monthly net burn. With $100,000.00 starting cash and $10,000.00 of net burn, the simple runway is 10.00 months.
The monthly table still matters. Recurring amounts apply in every month. The opening cash of the next month is the ending cash of the month before it. If one-time events are included, simple runway is not used as the depletion date. The first month whose ending cash is zero or below is the estimated cash-out month.
What is monthly gross burn?
Monthly gross burn is the recurring cash leaving the business each month before subtracting inflows. In this calculator it equals the monthly cash outflows you entered. It does not subtract collections, and it does not add one-time events.
What is monthly net burn?
Monthly net burn is monthly outflows minus monthly inflows when outflows are larger. If inflows are equal or higher, net burn is $0.00. The tool does not show a negative burn and does not call a surplus “negative runway.”
Cash inflows vs. revenue
Enter cash you expect to receive in the month, not only invoiced or accrued revenue. Revenue can be recognized before cash arrives. A sale on terms can raise revenue in one month and cash in a later month. This page does not convert an income statement into a cash forecast.
Cash outflows vs. expenses
Enter cash you expect to pay in the month. An expense can be recognized before or after cash leaves. Depreciation, amortization and other non-cash items are not deducted automatically. Include taxes, loan payments or owner draws only when you type them as monthly amounts or one-time events.
How one-time cash events affect runway
A one-time event is applied only in the projection month you select. It does not repeat. Several events in the same month are added together. An inflow in that month increases that month’s cash inflows. An outflow increases that month’s cash outflows. Events are not converted into weekly schedules, loans or interest.
Because events change the month-by-month path, the table is the source of the depletion month whenever events are included.
What happens when cash flow is positive?
If monthly inflows exceed monthly outflows, the recurring scenario adds cash each month. The tool reports positive cash flow. It does not say runway is unlimited. A later one-time outflow can still push a month to zero or below inside the horizon you chose.
How to read the monthly projection
Month 1 is the calendar month of the start date. Each row shows opening cash, cash inflows, cash outflows, net cash flow, ending cash and a status. Opening cash in month 2 is the ending cash from month 1. Recurring inflows and outflows appear in every row. One-time events appear only in the selected month.
The first month that ends at zero or below is labeled as the cash-out month, using the month and year, not a day. Later rows can show a projected shortfall because the model continues the same monthly math through the horizon.
Cash runway vs. working capital
Working capital in the Startup Cost Calculator is a reserve you choose: monthly costs times a number of months. Cash runway estimates how long cash you already have may last at the flows you entered. They answer different questions and are not substitutes for each other.
Limitations of this calculator
- Results are estimates based only on the numbers you enter.
- The model uses constant monthly inflows and outflows unless you add one-time events.
- Exact transaction days are not modeled. Depletion is shown as a month and year.
- This monthly projection does not model the timing of transactions within each month. A positive month-end balance does not rule out a temporary cash shortfall during the month.
- Revenue, profit, taxes, interest and financing are not calculated automatically.
- Loans, equity raises and credit lines are included only if you type them as amounts.
- The tool does not say cash will never run out, even when the horizon stays positive.
- A positive projected balance does not guarantee the business will have enough cash.
- Scenarios are not saved, exported or emailed.
- The estimate is not accounting, tax, legal or financial advice.
Frequently asked questions
What is cash runway?
Cash runway is an estimate of how long starting cash may last under the monthly inflows, monthly outflows and one-time events you enter. It is a cash-timing view, not a profit forecast or a legal finding.
How do I calculate cash runway?
When monthly outflows exceed monthly inflows and there are no one-time events, divide starting cash by monthly net burn. With $100,000.00 starting cash and $10,000.00 of net burn, the simple runway is 10.00 months. Events change the month-by-month path, so the table is the source of the depletion month.
What is monthly gross burn?
Monthly gross burn is the recurring cash leaving the business each month before subtracting inflows. In this calculator it equals the monthly cash outflows you typed.
What is monthly net burn?
Monthly net burn is monthly outflows minus monthly inflows when outflows are larger. If inflows are equal or higher, net burn is $0.00. The tool does not show a negative burn.
What happens if monthly inflows are higher than monthly outflows?
The scenario has positive monthly cash flow. Cash grows unless a one-time event inside the horizon pushes a month to zero or below. The tool does not call that unlimited runway.
How are one-time cash events included?
Each event is applied in the projection month you select. Multiple events in the same month are added together. Events do not repeat, and they are not converted into loans or weekly schedules.
Why is the cash-out date shown by month?
The inputs do not include exact transaction days. The projection applies recurring amounts and events within each month, so the first depleted month is labeled as a month and year, not a specific day.
Is revenue the same as cash inflow?
No. Revenue can be recognized before cash arrives. Enter cash you expect to receive, not only invoiced or accrued revenue.
Is profit the same as cash flow?
No. Profit is an accounting result. Cash flow is money moving in and out. A profitable month can still reduce cash, and a loss-making month can still increase cash.
What is the difference between cash runway and working capital?
Working capital is a reserve set aside to cover costs for a period you choose. Cash runway estimates how long the cash you already have may last at the flows you entered. They answer different questions.
Does this calculator include taxes or financing?
No. Taxes, loan draws, interest schedules and equity raises are included only if you type them as monthly amounts or one-time events.
How far into the future can I project?
The table can include 1 to 120 whole months. A longer horizon does not make the estimate more certain.
Can cash runway be unlimited?
No. If cash does not run out in the selected horizon, the tool reports that fact. It does not say cash will never run out.
Does a positive projected balance guarantee the business will have enough cash?
No. The table is a simplified constant scenario. Actual timing, customers, costs and events can differ. Because this monthly projection does not model the timing of transactions within each month, a positive month-end balance does not rule out a temporary cash shortfall during the month.
Last reviewed August 24, 2026 (UTC).