Cash Flow Forecast
Track a running cash balance across a sequence of periods from expected inflows and outflows, and see whether you dip negative or breach an overdraft limit.
Data verified · July 2026
What happens if inflows and outflows have different lengths?
The forecast runs for as many periods as there are inflow entries — any missing outflow for a period is treated as zero, so make sure both lists cover the same periods in the same order.
Source: ICAEW / ACCA management accounting — cash flow forecasting method; generic treasury practice on running balance and overdraft headroom monitoring. · updated 2026
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Everything about Cash Flow Forecast
📋Overview+
A cash flow forecast carries an opening balance forward period by period, adding expected receipts and subtracting expected payments to build a running balance. This calculator flags the lowest point the balance reaches, how many periods dip into deficit, and whether any period would breach an available overdraft limit — the earliest possible warning of a cash squeeze.
💡 Best practices
- Build inflows and outflows from realistic timing (when cash actually moves), not from invoice or accrual dates — a profitable period can still show a cash deficit.
- Re-run the forecast whenever a large one-off payment (VAT quarter, tax bill, capital purchase) is confirmed — these are the most common causes of a breach.
- If the forecast shows a deficit more than one period out, that is usually enough lead time to arrange additional headroom before it becomes urgent.
🔢 Concrete example
£10,000 opening balance, inflows of £10,000/£8,000/£12,000 and outflows of £9,000/£11,000/£7,000 across 3 periods: balance dips to £8,000 in period 2 but never breaches a £5,000 overdraft limit.
📖User guide+
How to use this calculator
- 1
Enter your opening cash balance for the first period.
- 2
Enter expected cash inflows for each period (comma-separated).
- 3
Enter expected cash outflows for each period (comma-separated, same order as inflows).
- 4
Enter your overdraft limit if you have one, to see if the forecast breaches it.
📚Glossary+
- Running balance
- The cash balance carried forward from one period to the next, updated each period by adding inflows and subtracting outflows from the prior balance.
- Margin of safety (cash)
- How far the lowest forecast balance sits above zero (or above the overdraft limit) — the cash cushion before the business runs out of funds.
ℹ️Sources & updates+
Last data update
July 7, 2026
Sources and references
ICAEW / ACCA management accounting — cash flow forecasting method; generic treasury practice on running balance and overdraft headroom monitoring.
The data in this calculator is updated regularly to reflect the latest official rates. When in doubt, consult the official sources listed above.
FAQ — Cash Flow Forecast
What happens if inflows and outflows have different lengths?+
The forecast runs for as many periods as there are inflow entries — any missing outflow for a period is treated as zero, so make sure both lists cover the same periods in the same order.
Does a positive closing balance mean the forecast is safe?+
Not necessarily — check the lowest balance and periods in deficit too, since a healthy closing position can still hide a dip that breaches your overdraft limit mid-way through.