Tool 02 · Cash flow

Cash-flow gap calculator

Your funding gap is the cash cushion your debtor days require, plus any shortfall where outgoings exceed income over the period, minus the cash you already hold. Enter your numbers to size the gap and see your projected balance month by month.

Your monthly numbers

Estimate only
What actually lands in the bank from customers, on average.
Wages, suppliers, rent, vehicles, repayments, GST and tax.
Average time customers take to pay after invoicing.

Your gap

Illustrative
Est. funding gap
$0
Monthly net
$0
Timing cushion
$0
Trading shortfall
$0
Less cash on hand
$0

Projected bank balance vs cushion needed

Estimate only. Real cash flow is lumpier — test a worse month too.

Talk about funding the gap

How is the funding gap calculated?

There are two ways a business runs out of cash, and the calculator measures both:

  • A timing gap. You pay wages and suppliers before customers pay you. At 45 debtor days, you're carrying about 1.5 months of outgoings at any time. Timing cushion = monthly outgoings × (debtor days ÷ 30).
  • A trading shortfall. For a stretch, more goes out than comes in. Shortfall = (outgoings − cash in) × months, only when outgoings are higher.

Then: funding gap = timing cushion + trading shortfall − cash on hand. If the answer is zero or less, your current buffer covers the scenario.

Is my problem timing or trading?

This is the most useful question the calculator answers. If most of the gap is the timing cushion, the business is fundamentally working — it's just waiting to be paid. That's a good fit for a line of credit or working capital loan, and a strong case for chasing debtors harder.

If most of the gap is a trading shortfall, look at why. A seasonal dip that reverses every year is fundable — see seasonal cash-flow planning. A shortfall that's been growing for a year is a pricing, cost or volume problem that funding alone won't solve.

Worked example

A Tauranga landscaping company brings in $62,000 a month on average and spends $66,000 over the winter months. Customers take 45 days to pay. It has $18,000 in the bank and wants to plan six months ahead.

ComponentCalculationAmount
Timing cushion$66,000 × 45 ÷ 30$99,000
Trading shortfall($66,000 − $62,000) × 6$24,000
Less cash on hand−$18,000
Estimated funding gap$105,000

Cutting debtor days from 45 to 30 would shrink the timing cushion by $33,000 — more than the entire winter shortfall. That's why our guide to reducing debtor days is worth ten minutes of your time.

How accurate is it?

It's a planning model, not a forecast. It assumes steady monthly figures, which real businesses rarely have. Use it to size the problem, then build a proper month-by-month forecast in your accounting software or a spreadsheet — and test the bad months, not just the average ones. For the theory behind it, read the cash conversion cycle explained.

Funding the gap

Businesses trading six months or more can often cover a gap with unsecured funding based on turnover and bank statements, with decisions sometimes same day. If you own property, a property-secured loan from $20,000 up to $1m is another route. Your inputs stay in your browser; nothing is stored or sent.

Frequently asked questions

What is a cash-flow gap?

A cash-flow gap is the difference between the cash a business needs to pay its bills on time and the cash it has available, over a set period. It's usually caused by timing — paying staff and suppliers before customers pay you — or by a period where outgoings exceed income.

What are debtor days?

Debtor days (or days sales outstanding) is the average number of days it takes customers to pay after being invoiced. Divide what customers owe you by your annual credit sales and multiply by 365 for a quick estimate.

Why does the calculator add a timing cushion?

If customers take 45 days to pay, you're effectively funding about one and a half months of costs at any time. Holding that as a cushion means an ordinary payment delay doesn't cause a missed payroll or supplier bill.

Should I include GST in outgoings?

Yes — include the GST you pay to IRD on average each month. If GST lands in lumps, the GST & provisional tax planner helps you convert it to a monthly or weekly figure.

What if the calculator shows no gap?

Great — you have enough buffer for the scenario you entered. Test a tougher one: a big customer paying 30 days late, a slow month, or a large tax bill.