12-Month Net Cash Burn Rate & Zero-Cash Runway Formula
Calculate trailing 3-month average net cash burn and projected runway in months without circular formula references in Microsoft Excel.
=LET( trailingOutflows, AVERAGE(TAKE(Cash_Ledger[Outflows], -3)), trailingInflows, AVERAGE(TAKE(Cash_Ledger[Inflows], -3)), netBurn, trailingOutflows - trailingInflows, treasury, Setup!CurrentCashBalance, IF(netBurn <= 0, "Cash Flow Positive", ROUNDDOWN(treasury / netBurn, 1)) )
Rolling 90-day average of actual operational bank debits.
Small Business Cash Flow & P&L
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The Problem with Standard Excel Approaches
Small business owners often mistake accounting net income for cash flow, running out of money while appearing profitable on an accrual basis.
How Modern Dynamic Arrays Execute This Formula
Pulls cleared bank transaction data rather than accrual invoice dates.
Calculates smooth 3-month moving average to eliminate seasonal monthly noise.
Checks whether the business is net cash generative or burning reserves.
Outputs runway months and zero-cash date directly into executive dashboard.
Common Excel Errors & How to Fix Them
Solution: Handled cleanly by IF condition returning 'Cash Flow Positive'.
Solution: Decouple operating cash forecasts from interest accrual.