Startup Cash Stress Test: How Many Weeks Do You Have If Revenue Drops 30%?
A stress test asks one question: if things go worse than planned, how long does the cash last? Take your 13-week cash forecast, change two or three assumptions, and see which week the balance falls below your safety buffer. Do it quarterly and before every raise or big commitment. It takes about an hour once the forecast exists.
Step 1: start from a real forecast
Use your current 13-week cash forecast with real bank balances, known payroll and rent, and expected collections by week. If you do not have one, build that first; a stress test on guesses gives false comfort.
Step 2: change the assumptions that hurt most
- Revenue 30% lower than forecast for the next 13 weeks
- Customers paying 15 days later than terms
- One large customer lost
- A planned raise slipping by two months
- A major cost, such as a hire or a software contract, arriving earlier
The percentages are examples. Use ranges that are realistic for your business.
Step 3: read the result
- Mark the first week the closing balance falls below your safety buffer
- Note how many weeks earlier that is than in the base case
- Rank the assumptions by how much they bring the date forward
- Pick the one or two that deserve a response plan
Step 4: write the response plan before you need it
For each risk, decide in advance: which costs pause, which customers you call, what the trigger date is for starting a raise, and who decides. A plan written in a calm week is better than a decision made in a crisis week.
Use the free tools
The cash runway calculator and the 13-week cash flow template let you run the scenarios above yourself. If you want a second pair of eyes on the assumptions, book a free discovery call.
Frequently asked questions
A test of how long cash lasts if results are worse than planned, done by changing assumptions in your cash forecast and finding the week the balance falls below your safety buffer.
How often should a startup run one?Quarterly, and before a raise, a large hire or a major contract.
What assumptions should I stress?Lower revenue, later customer payments, a lost large customer, a delayed raise and costs arriving earlier than planned.
Is a stress test the same as a forecast?No. A forecast is your best estimate; a stress test shows how much room you have if the estimate is wrong.
Want this set up for your startup?
Book a free discovery call. We review your numbers and agree what to fix first, with no cost and no obligation.
Written by Akram El-Karrar, CPA, from the work we do for startups every week.