Cash Runway Calculator
See how long your cash lasts under your plan.
Your outlook
Flat cash runway
Enter available cash, monthly cash received and operating payments to see your flat runway.
The method
Follow the cash through every month.
Gross burn is monthly operating cash paid out. Net burn subtracts monthly cash collected from those payments. A positive net burn consumes your reserve; divide current cash by that burn for the flat runway. Growth adds a different question: can you fund the months before cash inflows cover operating outflows? The planner keeps the flat baseline visible and models the changing path separately.
Example 1
Six months flat. A different path with growth.
Start with $120,000 cash, $20,000 monthly cash inflows and $40,000 in operating outflows. The flat runway is 6.00 months. With 10% monthly growth in cash inflows and unchanged operating outflows, Month 1 still uses $20,000 in cash inflows. Cash ends Month 8 at $28,717.76. Month 9 cash inflows are $42,871.77, covering operating outflows for the first time. Cash ends Month 12 at $67,685.67 and does not deplete within the 60-month modeled scenario.
- Flat runway
- 6.00 months
- Operating coverage
- Month 9
- Cash after 12 months
- $67,685.67
Example 2
Ending positive does not fund an earlier shortfall
Use the same cash inflows, operating outflows and growth with only $60,000 starting cash. Cash first depletes about 3.46 months in. A hypothetical Month 12 balance is still positive at $7,685.67, but the business needs $91,282.24 of starting cash to keep every earlier balance nonnegative. The peak need occurs in Month 8, so the additional cash requirement is $31,282.24. Later recovery cannot pay an earlier bill.
- Required reserve
- $91,282.24
- Additional cash
- $31,282.24
- Peak cash need
- Month 8
Before you calculate
Assumptions & limits
- Use available cash, monthly cash received and operating cash paid out, all in the same currency. Booked revenue that has not been collected is not cash. USD is the display convention; no conversion is performed.
- Month 1 uses exactly the entered monthly cash inflows and operating outflows. Growth applies afterward to produce Month 2, then compounds each month. Following-month amounts round to the nearest cent, with midpoint ties away from zero. Those rounded cents are reused in the next calculation.
- Money inputs accept 0–999999999.99, with up to two decimals and no signs, commas or symbols. Growth accepts −100.00% to 100.00%, with up to two decimals and an optional minus sign; plus signs, exponents and % symbols are not accepted. The positive bound is an input limit, not a growth recommendation. A zero amount stays zero under percentage growth.
- Both growth fields blank means a flat-only calculation. Either field entered, including zero, enables a growth scenario; its blank counterpart means zero growth. An optional target accepts 1–60 whole months. The calculation horizon is fixed at 60 months; chart and table controls change the view only.
- Modeled cash inflows, operating outflows, cash balances and cumulative net cash use are limited in magnitude to 999999999999.99. If the next month would exceed this limit, the calculation stops before that row. Later milestones and targets are marked unavailable; completed earlier results remain valid.
- Flat and within-month runway estimates assume net cash movement is evenly distributed. Actual payment and collection dates may differ. Zero starting cash provides no reserve, even when total monthly receipts cover expenses. Month numbers are estimates, not promised bank-balance dates.
- Monthly operating cash-flow break-even means cash inflows are at least operating outflows in that month. It is not accounting profitability. Reaching coverage once does not guarantee future coverage if outflows and inflows subsequently change at different rates.
- Required starting cash funds the largest cumulative deficit over all prefixes of the target period. Ending balance alone cannot reveal that requirement. The minimum allows cash to touch zero and includes no contingency buffer or funding costs.
- Projections continue after the first depletion to show potential deficits and recovery. This assumes the business could keep operating and would fund shortfalls somehow; no overdraft or financing facility is modeled. A later positive balance does not reverse an earlier depletion event.
- No one-time costs, fundraising, debt, taxes, noncash charges, working-capital timing, receivables delays, seasonality, random shocks, capacity limits or demand response are added. Rates are scenario assumptions, not a guarantee or forecast of future growth.
Keep in mind
Common mix-ups
Using gross burn when cash inflows offset operating outflows
A business spending $40,000 and collecting $20,000 has $40,000 gross burn but $20,000 net burn. The flat reserve lasts against the net cash use.
Growing cash inflows before Month 1
A 10% rate on $20,000 gives $22,000 in Month 2. Applying it to Month 1 would add cash a month too early and shift every milestone.
Treating monthly coverage as permanent safety
Cash inflows may cover operating outflows today and fall behind later as costs rise. The planner continues through the horizon and retains the first cash depletion, even if a later month rebuilds the balance.
Confusing a funding requirement with an ending balance
For a funding decision, compare required starting cash with your available cash, not just the ending balance. The peak requirement captures earlier bills that later receipts cannot pay.
Need to bill completed work? Create a PDF with the Invoice Generator. Use actual receipts, rather than invoiced amounts, in this cash plan.
Sources & calculation notes
Reference for gross and net burn. Our growth timeline, rounding, numeric limits and target-funding model are explicit product assumptions described above.
Reference for monthly cash expenses, revenue-offset net burn and cash divided by net burn. No industry runway rating or recommended reserve is inferred here.
Calculation and input rules checked: . Engineering validation; no professional accounting review is claimed.