Cash Flow Forecast Calculator
See how much cash you will have left in six months — and how long your runway lasts
Updated 2026-09-09
- Net cash per month
- -$800.00
- Cash after 6 months
- $200.00
- Months of runway
- 6 months
You are spending more than you take in. Runway is how long the current balance covers the gap before the account hits zero.
Your numbers stay on this device. The page link keeps your inputs, so a bookmark or shared link reopens these results.
Profitable businesses close every week because the money arrives later than the bills. A forecast is the cheapest insurance against that: it shows the month your balance turns negative while there is still time to fix it. Enter four numbers and read your runway.
What cash flow forecasting actually tells you
Profit is an accounting result; cash is what pays wages on Friday. A shop can book a profitable month, ship the goods, and still be unable to cover rent because the customer pays in sixty days and the supplier was paid in seven.
A forecast puts those timings side by side. Net cash per month is money in minus money out. Multiply it across the months ahead and you get your ending balance; divide today's balance by a negative monthly figure and you get the number of months before the account empties.
What belongs in "money coming in"
Only cash you will genuinely receive inside the month.
- Card and cash takings, net of processing fees
- Invoices you expect to be paid this month, not those merely issued
- Deposits and prepayments from customers
- Loan drawdowns, grants, or owner contributions
- Refunds and rebates you are actually owed
What belongs in "money going out"
Include everything that leaves the account, including the irregular items owners routinely forget.
- Stock purchases and inbound freight
- Rent, utilities, insurance, and software subscriptions
- Wages, contractor payments, and your own draw
- Sales tax and income tax set-asides
- Loan and card repayments, plus annual renewals divided by twelve
How to read a negative runway
A runway of four months is not a crisis; it is a deadline. The fixes fall into three buckets, and most owners need two of them at once: pull cash in earlier, push cash out later, or change the underlying margin.
Pulling cash in usually means shorter payment terms, deposits on larger jobs, and chasing the receivables you already earned. Pushing cash out later means negotiating supplier terms and delaying non-essential purchases — not skipping tax payments. Changing the margin means pricing, product mix, or shedding the slowest stock.
How often to refresh the forecast
Monthly is enough for a stable business; weekly is right when runway is under six months or takings swing hard by season. The discipline matters more than the precision — a rough forecast reviewed every month beats a detailed one built once.
Keep a reserve target alongside it. Three months of operating expenses in the account is the widely used floor for small businesses with lumpy income.
Keep the numbers in a spreadsheet
Ready-made Excel and Google Sheets templates that pick up where this calculator stops. One-off purchase, instant download.
12-Month Cash Flow Forecast & Business Budget Spreadsheet
Sales with growth, seasonality and collection timing, every expense, closing cash, low-cash alerts and variance.
Simple Profit & Loss (P&L) Statement Spreadsheet
Log transactions; get a monthly and yearly P&L with margins.
Frequently asked questions
What is cash runway?
The number of months your current bank balance covers the gap when you spend more than you take in. Balance divided by the monthly shortfall.
Should I include tax in the forecast?
Yes. Sales tax collected is not your money, and income tax comes due eventually. Treat both as cash going out in the month you set them aside.
How far ahead should I forecast?
Six to twelve months for planning, and a rolling thirteen weeks when cash is tight — weekly detail is what catches a specific bad week.
Is this the same as a profit forecast?
No. A profit forecast records income when it is earned; a cash forecast records it when it lands in the bank. The gap between them is what causes most small business failures.
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