Cash Runway Forecast Calculator

The lowest balance is what matters.

The lowest balance is what matters. A plan that dips below zero in month three and recovers afterwards still fails.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Currency

Cash available

Monthly revenue

Monthly costs

Monthly revenue growth

Monthly cost growth

Planned one-off investment

Month of that investment

Runway

over 10 years

break-even in month 5

Starting cash$180,000

Planned investment−$40,000

Lowest cash balance$101,885

Break-even month5

The lowest balance of $101,885 is what matters, not the ending one, a plan that dips below zero in month 3 and recovers afterwards still fails. Timing the investment differently is often cheaper than raising more.

How the Cash Runway Forecast Calculator works

A plan that dips below zero in month three and recovers afterwards still fails. The lowest balance is what matters, not the ending one, and timing a planned investment differently is often cheaper than raising more money to survive it.

Also known as: runway projection calculator · months of cash remaining · forecast when cash runs out

Forecasting the balance rather than dividing by burn

Runway as cash divided by burn assumes constant burn, which no product business has. The useful version is a month-by-month forecast of the closing balance.

The structure is opening balance, receipts, payments, closing balance, repeated. Runway is the month the closing balance goes below zero, which is nearly always sooner than the division suggests.

The difference is caused by lumpy payments: stock orders, VAT quarters, corporation tax, annual renewals. A business with six months of runway on the simple calculation frequently has three once the payment schedule is laid out.

Getting the receipts right

Sales are not receipts. Card payments settle in days, marketplaces on their own schedule, and trade customers on terms.

A business selling on Amazon with a fourteen-day settlement receives a fortnight after the sale, and the reserve on new accounts extends that. Forecasting receipts as if they arrived with the order overstates the position by that period.

Refunds have to come off, and they lag sales. A forecast that shows gross sales as receipts and puts refunds in a separate line at an annual average will be wrong in both directions across a seasonal year.

The payments that are easy to forget

VAT quarters are the most commonly missed, and they are large. A business accruing VAT on sales and paying it quarterly has three months of accumulation leaving in one payment.

Corporation tax, nine months after the year end, is far enough away to be forgotten and large enough to matter. Loan principal repayments, which do not appear in the profit statement at all. And the stock orders, which are the largest and the most controllable.

Listing the known large payments for the next twelve months, with dates, is the single most useful hour available to a small business owner. Most have never done it, and most are surprised by what the list contains.

Scenarios rather than a single line

Three forecasts, base, downside and upside, give a range rather than a false precision.

The downside is the one that determines action. It should be genuinely pessimistic: sales 25% below plan, a stock order delayed, a customer paying late. If the business survives that, the position is sound; if it does not, the plan needs changing now rather than then.

The upside needs modelling too, because unexpected growth consumes cash for stock. A business that has only planned the downside can be caught out by a good quarter, which is a better problem and still a problem.

Acting on it early enough

The value of a runway forecast is entirely in acting on it, and the actions available depend on how much time remains.

Above six months, structural options exist: renegotiating supplier terms, arranging a facility, reducing stock levels, cutting costs in an orderly way. Each takes weeks to months.

Below three months, only fast options remain: stopping discretionary spend, discounting stock to convert it to cash, and asking for help. Those are more damaging and less effective, which is why the trigger to act should be set in advance at a number of months rather than decided when the position becomes uncomfortable.

Where to go next

The Cash Runway Forecast question rarely arrives on its own. These are the ones that usually come with it:

Runway Calculator — Growth extends it, if the growth holds.
Burn Rate Calculator — Gross burn and net burn are different.
Sales Forecast Calculator — Plan stock and cash against the peak.
Etsy Fee Calculator — Every Etsy fee on one sale, itemised.

Not financial advice. Marketplace fees change, and they vary by country, plan and seller status. Every rate here is an editable default, not a quoted price, check the platform's current fee schedule before you price a product against it. This is not tax or business advice.

Frequently asked questions

How do I forecast cash runway?

Month by month, with revenue and costs growing at their own rates and any one-off investments placed in the month they occur. Averages hide exactly the dip that kills you.

Why does the lowest balance matter most?

Because you cannot survive a month with negative cash by pointing at a positive twelve-month total. The trough is the binding constraint.

Should I model a downside case?

Always. A plan that only works at the forecast growth rate is not a plan. Model flat revenue and see whether the business survives it.

How do I extend runway without raising?

Delay discretionary investment, negotiate supplier terms, collect faster, and cut the costs that do not produce revenue. All four are available before a raise and all four are usually cheaper.

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