The standard cash runway formula reports that a profitable business will never run out of money. That reads like the best possible answer, right up until a hire or new lease is on the table and you need to know what the current cash actually covers. An infinite number can't help you make that call.
Calculating cash runway for an established business means picking the right denominator. Divide your cash balance by average monthly net burn when you spend more than you collect. Divide by average monthly operating expenses when you don't.
Why the standard cash runway formula fails for a profitable business
The standard formula assumes your business spends more cash than it collects every month. Net burn means monthly cash out minus monthly cash in. The assumption that monthly outflows exceed inflows describes a venture-backed startup counting down to its next raise rather than an established, revenue-generating business.
For a business earning close to or above its expenses, net burn hovers near zero. Dividing by a number near zero produces an enormous or infinite result. That result doesn't help with planning. The metric stops being useful when you're deciding whether the business can absorb a new salary or lease during a slow quarter.
Established businesses still need enough cash to cover operating expenses because a lost client or late-paying customer can test the reserve. Last year's profit and loss (P&L) statement may not reflect the cash available today. An accrual-basis P&L can count revenue before the cash reaches your account. According to the 2026 Federal Reserve report, 56% of firms that applied for financing in the prior 12 months did so to meet operating expenses.
Burn rate is one of several cash flow metrics worth tracking, but it can't tell a profitable owner how long the cushion lasts on its own.
Choose the denominator that matches your situation. Seasonal businesses also need to account for their weakest months.
Calculate cash runway from bank activity
Cash runway = total cash balance ÷ average monthly net burn. Build the calculation from actual bank activity so invoiced revenue doesn't inflate the cash available today.
Run the formula
The steps, in order:
Total your cash balance across every business account. Include checking and savings balances you could spend this month. Count money the business holds and exclude money it expects.
Calculate average monthly net burn from the last 3–6 months of actual bank activity. For each month, subtract cash in from cash out, then average the results. Use bank statements because an accrual-basis P&L may include invoiced revenue that hasn't reached your account.
Divide the balance by the net burn. The result is your runway in months.
Take a hypothetical services business. It holds $180,000 in cash. Over the last six months, it averaged $75,000 in monthly cash out and $65,000 in monthly cash in. Of that $75,000 going out, $60,000 is recurring business expenses. The remaining $15,000 is quarterly tax payments, owner pay, and one-off purchases. Net burn is $75,000 − $65,000 = $10,000. Runway is $180,000 ÷ $10,000 = 18 months.
Walk through a full example
Take a marketing consultancy with three retainer clients and one project-based client. At month-end, checking holds $142,000 and savings holds $38,000. Total cash balance: $180,000.
Pull the last six months of bank activity:
January: $71,000 in, $73,000 out
February: $68,000 in, $76,000 out
March: $64,000 in, $74,000 out (annual insurance premium hit this month)
April: $63,000 in, $77,000 out
May: $66,000 in, $75,000 out
June: $62,000 in, $75,000 out
Average monthly cash in is $65,667. Average monthly cash out is $75,000. Average monthly net burn is $75,000 − $65,667 = $9,333. Unadjusted runway is $180,000 ÷ $9,333 = 19.3 months.
Now subtract near-term committed outflows. Next payroll is $22,000 on the 15th. Q3 estimated taxes are $18,000, due the same week. Two vendor bills totaling $4,500 are due before the next client deposit arrives. Spendable starting balance: $180,000 − $44,500 = $135,500. Recalculated runway: $135,500 ÷ $9,333 = 14.5 months.
At 19 months, a $6,000-a-month hire looks obviously affordable. At 14, the same decision is closer to the edge once payroll, taxes, and vendor bills leave the account. Running the adjustment before signing an offer letter changes what you commit to.
Use a rolling average
Use a rolling 3–6 month average because a single unusual month distorts the number. An annual insurance premium inflates one month's outflows; a large one-time deposit deflates them. A rolling window smooths both. Keep the window the same length each time you recalculate. When a new month closes, add it to the calculation and remove the oldest month. Each month's number then stays comparable to the last.
Review the monthly inputs before accepting the average. A large payment may belong to a normal quarterly cycle rather than an unusual event. Keeping it in the calculation can give you a more conservative runway figure. Pausing one-off purchases can show how long cash lasts after discretionary spending stops.
If step 3 hands you a zero or negative denominator, continue with the profitable-business calculations below.
Count owner pay, receivables, and your line of credit
Use collected cash and actual bank outflows for each input:
Owner pay goes in the burn. Count your full draw or salary in monthly outflows. At $14,000 a month against $75,000 in total cash out, owner pay is nearly a fifth of monthly cash out. Treat it as a normal calculation input here, even though it's often the first line you'd flex in a crunch.
Accounts receivable stays out of the balance. Invoicing a client doesn't put money in the account, and delayed payment terms can leave a healthy P&L sitting next to a thin bank account. Use the available bank balance.
Undrawn credit stays out of the balance. Exclude a line of credit from runway and keep it as a backstop. Calculate how long your own cash lasts before considering borrowed money.
Those three choices keep expected or borrowed money out of the balance so the runway number reflects cash you actually hold.
Subtract committed outflows
Subtract near-term committed outflows from your cash balance only if the runway period begins after those payments leave the account. Include the next payroll run, quarterly taxes, and open vendor bills, but don't count those same payments again as first-period outflows. The result is your spendable starting balance.
For the $180,000 example, list each committed payment beside the date it will leave the account. Subtract every payment due before the next expected customer deposits arrive. Don't count the full balance as runway if part of it already belongs to employees, tax authorities, or vendors. Adjusting for those commitments keeps a strong-looking account balance from overstating the cash available for a new hire or lease.
Separate committed money into dedicated accounts so you can read the available balance without estimating it. Relay lets you split cash across up to 20 separate checking accounts, so payroll, tax, and reserve balances, and operating cash are visible on their own.
Adjust the denominator for positive or seasonal cash flow
Positive or seasonal cash flow needs a denominator that reflects the decision you're making. A profitable business can measure expense coverage, while a seasonal business should plan against its weakest months.
Choose the denominator when cash flow is positive
For a profitable business, choose among three expense-based runway calculations based on the decision you're making:
Months of expenses covered: cash ÷ average monthly operating expenses. The default check before committing to a new fixed cost.
Stress-test runway: rerun the standard formula with revenue cut 40%. Use it when a hire or lease adds cost that survives a downturn even if revenue doesn't.
Survival-mode runway: cash ÷ non-negotiable monthly obligations only, including rent, insurance, core payroll, and other required bills. Use it for minimum-cost planning, since discretionary spending stops fast in a crunch.
Using average monthly operating expenses gives this business three months of runway. The stress test uses the same $60,000 operating base, with the $15,000 of tax timing and one-off purchases paused. Cash in falls 40% from $65,000 to $39,000. Monthly net burn becomes $60,000 − $39,000 = $21,000. The standard formula produces a finite answer again: roughly 8.5 months.
The three-month result assumes revenue stops while monthly operating expenses continue. The 8.5-month result assumes customer deposits continue at 60% of their recent average. Run both versions before adding a fixed cost. One shows how long the business could operate with no revenue. The other models a steep but partial slowdown.
Profitability doesn't guarantee that customer payments will arrive before payroll, rent, and other fixed bills come due. Revenue predictability and fixed costs should shape your target for business cash reserves.
Adjust cash runway for seasonal revenue
A seasonal business calculates runway twice, once on the annual average and once on its worst months, and plans against the second number. A business booking roughly 55% of its revenue in five peak months can show an annual-average net burn near zero. On paper, that looks like unlimited runway. Its worst three consecutive months might show $25,000 of monthly net burn. Against $180,000 in cash, $180,000 ÷ $25,000 is about seven months of off-season survival, which changes how the business plans through the slow season.
The method uses bank data you already have:
Pull the last 12 months of bank activity. Use the same window to start next year's cash flow forecasting.
Find the worst consecutive three-month stretch of net cash flow. Treat that historical worst stretch as the starting assumption for the slow season.
Check whether the three weak months include predictable annual payments, such as insurance or taxes. Keep them in the off-season calculation if they'll recur during the same period next year. If a purchase won't repeat, calculate the result both with and without it so you see the conservative and adjusted versions.
Use the monthly net burn from that stretch as the denominator. Divide your cash balance by that figure to get off-season runway in months.
Set the peak-season reserve target. Three months at $25,000 of net burn is $75,000 the peak months must bank before the slowdown starts. Moving a percentage of every peak-season deposit into the reserve builds that balance as revenue arrives.
Relay's automated transfers can split incoming deposits by percentage or fixed amount on every plan. A percentage rule during strong months fills the seasonal reserve without requiring a manual transfer after each deposit. Compare the reserve balance with the $75,000 target at month-end and adjust the percentage if it falls behind.
Put your runway number on a monthly schedule
Recalculate your runway at month-end so the figure reflects current cash and expenses when you decide whether to add a hire, lease, or other fixed cost. The useful number depends on two choices: a spendable starting balance that excludes committed outflows and a denominator that fits your cash flow. Recalculate both from current account balances and expense data each month.
At month-end, read the balances for operating cash and reserves, then subtract committed outflows. Relay shows operating money, committed cash, and reserves in separate accounts, so the reserve figure is legible without recalculating from a combined balance. QuickBooks Online two-way sync keeps the expense side of the calculation current.
The number you calculated today will be stale in thirty days because cash and expenses change. You can keep the calculation current by opening a Relay account, separating reserves from operating cash across multiple checking accounts, and setting percentage-based transfers to move reserve allocations after deposits arrive.
Frequently asked questions
What is a good cash runway for a small business?
No single cash-runway benchmark fits every small business. The right target depends on how predictable your revenue is and how heavy your fixed costs are. Seasonal businesses and businesses that depend on one or two large clients should target the higher end.
What's the difference between burn rate and cash runway?
Burn rate is the speed at which your business consumes cash each month; runway is how many months your current balance lasts at that speed. Burn is the denominator in the calculation, and runway is the result. Two businesses can burn the same amount each month and have very different runway because the cash balance behind the burn sets the count.
Does accounts receivable count toward cash runway?
Only after the client pays. Add the cash to your next runway calculation once it reaches the account.
Should a line of credit count as part of my runway?
A line-of-credit draw enters your cash balance only after the lender deposits it, but track the borrowed portion separately from your own cash. Calculate your runway on business cash first so borrowed money doesn't hide how thin the reserve is.
How often should I recalculate my cash runway?
Use month-end as your regular checkpoint, then run the calculation again after a major change. A new hire, lost client, equipment purchase, or lease can shift the denominator enough to change the answer.
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