Cash Runway Calculator: Months Until Cash Runs Out
Enter your cash balance, monthly revenue and monthly expenses to see how many months of cash runway you have and how many days until you hit zero. Add a monthly revenue growth rate if sales are rising. It looks only at cash out versus cash in.
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Formula
For month t (the first month is t = 1):
revenue(t) = revenue × (1 + g)^(t − 1), wheregis the monthly growth rateburn(t) = expenses − revenue(t)- Cash is reduced by
burn(t)each month; the month in which it runs out counts as the fractioncash left ÷ burn(t). - With no growth this is simply
runway = cash ÷ (expenses − revenue). Days until zero cash = runway in months × 30.4375, rounded down.
Worked example
Cash 100,000, revenue 10,000, expenses 30,000, growth 10% a month. Burns are 20,000, 19,000, 17,900, 16,690 and 15,359 (total 88,949) over five months. The remaining 11,051 covers 11,051 ÷ 13,894.90 = 0.795 of month six, so the runway is 5.8 months, or 176 days. With no growth it would be 100,000 ÷ 20,000 = 5 months.
Another example
Cash 60,000, revenue 5,000, expenses 15,000 and growth of 5% a month. The burn starts at 10,000 and shrinks as revenue grows (10,000, 9,750, 9,487.50 and so on). Cash lasts 6.5 months, about 197 days. With no growth the runway would be 60,000 ÷ 10,000 = 6 months.
Rules of thumb
Many startups aim to keep 12 to 18 months of runway and start raising or cutting costs well before it falls under 6, because deals and hiring take time. Treat these as generic guides.
Common mistakes
- Using last month's burn for a business with seasonal costs.
- Forgetting annual bills, tax payments and loan repayments that land in one month.
- Assuming growth that has not happened yet.
- Mixing gross burn (all spending) and net burn (spending minus revenue). Runway uses net burn.
How it differs
Runway counts time until cash runs out. The working capital calculator measures short-term liquidity from the balance sheet, break-even finds the sales level where you stop burning, and MRR tracks the revenue that offsets burn.
Frequently asked questions
How do you calculate cash runway?
Divide your cash by your net monthly burn (expenses minus revenue). With 120,000 in cash and a burn of 20,000 a month, the runway is 6 months.
How does revenue growth change the runway?
Each month the calculator raises revenue by the growth rate, so the burn shrinks over time. With 100,000 cash, 10,000 revenue, 30,000 expenses and 10% monthly growth, the runway is about 5.8 months instead of 5.
How is the zero-cash day count worked out?
It is the runway in months times 30.4375, the average length of a month, rounded down. A 6 month runway is 182 days. Add that many days to today's date to find the zero-cash date.
Why does it say my cash does not run out?
If revenue covers expenses your cash does not fall, so there is no date when it runs out. The calculator then shows a runway of 0 with the note that cash does not run out within 50 years; a runway is only reported when cash is being used up.
What is the cash runway formula?
Runway in months = cash ÷ net monthly burn, where net burn is monthly expenses minus monthly revenue. With 60,000 of cash, 15,000 of expenses and 5,000 of revenue, burn is 10,000 and runway is 6 months. Revenue growth lengthens it.
How many months of runway should a startup have?
As a rule of thumb, 12 to 18 months after a funding round is a common target, with alarm bells below 6 months. Raising money often takes 3 to 6 months, so a 6 month runway can be too short to act. Your own plan and growth matter more than any rule.
What is the difference between gross burn and net burn?
Gross burn is total monthly spending; net burn is spending minus revenue. With 15,000 of expenses and 5,000 of revenue, gross burn is 15,000 and net burn is 10,000. Runway is based on net burn, so higher revenue extends it even if costs stay the same.