How many months of runway if revenue drops by 50%?
Half your revenue disappears. It sounds extreme, but it is exactly what happens when a major client leaves or a market downturn cuts your pipeline in half. Here is how to calculate whether you would survive it.
The short answer
How long would your cash last at half revenue? Take your monthly expenses, subtract 50% of your monthly revenue. The gap is your net monthly cash burn. Divide your cash by that burn rate. For most small businesses, a 50% revenue drop turns a profitable month into a cash-draining one fast.
When half your revenue disappears overnight
A 50% revenue drop is not a slow decline you can adjust to. It is a shock. Your largest client goes bankrupt. A regulatory change kills your top product line. A global event shuts down your industry for months.
The businesses that survive these shocks are the ones that already knew the answer to this question. They had enough cash to cover the gap, or they had a plan for what to cut immediately. The ones that did not know were the ones scrambling for emergency loans, laying off staff, and hoping for the best.
This stress test is not about paranoia. It is about knowing exactly how much trouble you would be in so you can decide whether your current cash reserves and expense structure are adequate.
The 50% revenue stress test calculation
The math is the same as any runway calculation, but with revenue cut in half:
Notice how dramatically this differs from the 25% scenario. A 25% drop gave 7.3 months. A 50% drop gives 3.1 months. The relationship between revenue decline and runway is not linear. Each additional percentage of lost revenue accelerates the burn rate.
How to model a 50% revenue decline in QuickBooks Online
Same two reports as the other runway calculations. The scenario math is where this one gets real.
- 1Pull your P&L for the last 3 months
Go to Reports→ “Profit and Loss.” Set the date range to the last 3 months. Note Total Income and Total Expenses. Divide each by 3 for monthly averages.
- 2Get your cash from the Balance Sheet
Go to Reports→ “Balance Sheet.” Set date to today. Note “Total Bank Accounts” under Current Assets.
- 3Calculate the 50% scenario
Monthly revenue x 0.50 = adjusted revenue. Monthly expenses minus adjusted revenue = net burn. Cash / net burn = months of runway. Write this down. Then ask: could you survive on this timeline?
- 4Model emergency cuts
Go back to your P&L and look at each expense category. If revenue dropped 50%, what would you cut immediately? Ad spend, contractors, non-essential software. Recalculate runway with those cuts. This gives you a “survival mode” runway number that is more realistic.
Total time: about 15-20 minutes. The math takes 5 minutes. The hard part is honestly assessing which expenses you could cut and how fast.
How to model a 50% revenue decline in Xero
Same approach. Pull the two reports and do the scenario math.
- 1Get revenue and expenses
Go to Accounting → Reports→ “Profit and Loss.” Set the period to 3 months. Note Total Revenue and Total Operating Expenses. Divide by 3.
- 2Get your cash
Go to Accounting → Reports→ “Balance Sheet.” Find “Bank” under Current Assets.
- 3Run the scenario
Revenue x 0.50, subtract from expenses, divide cash by the gap. Compare this number against the 25% scenario and the zero-revenue scenario to understand how your risk accelerates with each level of decline.
Total time: about 15 minutes. The real value comes from running all three scenarios (25%, 50%, zero) side by side. That takes closer to 30 minutes with a spreadsheet.
Why running multiple scenarios every month is impractical
One stress test is 15 minutes. Three scenarios (25%, 50%, zero) is 30-45 minutes. Doing that every month while running a business is asking a lot.
- You need the same reports every time. P&L, Balance Sheet, and a spreadsheet template. If you lose the spreadsheet or change the format, you lose your historical comparison.
- The value is in the trend. A single number is interesting. Six months of numbers tells you whether you are getting more resilient or more fragile. That requires consistent monthly tracking.
- Your accounting software does not do scenario modeling. QuickBooks and Xero show you what happened. They do not show you what would happen if conditions changed. That gap is where stress testing lives.
Or get all three stress tests automatically, every month
Bottomline runs the 25%, 50%, and zero-revenue scenarios automatically on the first of every month. It uses your actual financial data from QuickBooks or Xero and shows all three results side by side.
Bottomline also tracks how these numbers change over time. If your 50% scenario runway was 4 months in January and is now 3.1 months in April, your report shows the trend and flags the decline. You see the problem building before it arrives.