Deep-dive guide
Startup Runway and Burn Simulator: How Many Months Until the Cash Runs Out
Executive industry analysis
Runway is the number of months until the bank balance reaches zero, and every other startup metric is secondary to it. A company can have strong growth, happy customers and a brilliant product and still fail on a particular Tuesday, because the money ran out before the next round closed. What makes runway hard to manage is that it is not fixed. It moves with every hire, every churned customer and every delayed deal, and the changes arrive slowly enough to be ignored until they become urgent.
The structure of the problem is a race between two lines. Revenue grows by a percentage each month; costs grow in steps, because people are hired in blocks and salaries are sticky. When growth is high and hiring is modest, revenue overtakes cost and the company becomes self-sustaining. When hiring is planned for a growth rate that does not arrive, the gap widens every quarter. This model averages both lines over the next twelve months to give a single monthly result.
The domino model follows the race in five steps. The average revenue over the year sets what the business can pay for. Payroll takes a share of it. The cover ratio compares revenue with all costs together. If it is below one, the company burns cash, and the runway box converts that burn into months using the balance. Finally the monthly result shows whether the company is building or consuming its cushion. A small slip in growth or a single extra hire can move the cover ratio under one.
The iceberg separates the cost everyone budgets from the costs they forget. Above the waterline are salaries and the direct costs of serving customers. Below it are per-head expenses such as laptops, software seats, benefits administration and travel; recruiting fees and the weeks of lost output while a new person ramps up; and the fixed overhead of legal, accounting, insurance and office. A new hire costs far more than the salary line suggests. Use the simulator to find the growth rate or hiring pace at which your month turns negative.
Formula and methodology blueprint
The model works per month, averaged over the next twelve months. Revenue is the current recurring revenue times the average growth factor, which is the mean of the compounded monthly growth over a year. Headcount is the current team plus the average number of hires on payroll, assuming people join at the start of each quarter. Costs are payroll, a per-head charge, serving costs at a share of revenue, recruiting at about two months of salary per hire, and fixed overhead. Runway is cash divided by the monthly loss.
- Average revenue
- R = MRR × mean of (1 + g)^t over 12 months
- Recurring revenue lifted by compounded monthly growth, averaged across the year.
- Average headcount
- H = team + 1.5 × hires per quarter
- Hires join in blocks each quarter, so on average one and a half quarters of hires are on payroll.
- Payroll and per-head costs
- P = H × (salary + $900)
- Salaries and the recurring cost of equipment, tools and benefits administration.
- Recruiting
- Rc = hires per year × salary × 2 ÷ 12
- Recruiter fees and ramp-up time spread across the year.
- Net and runway
- Net = R − P − 22% R − Rc − fixed; runway = cash ÷ −Net
- The monthly result and the months of cash left when it is negative.
Cascading elasticity
Monthly growth and recurring revenue are the most elastic inputs because they compound across the year. Salary and team size follow, as they set the largest cost line. Hiring pace is deceptive: one extra hire per quarter adds both payroll and recruiting costs, and the effect builds up. Cash does not change the monthly result but fully decides how long a loss can be survived.
Three real-world case studies
Bootstrapped starter
Two founders in a small bootstrapped start
Two founders draw modest salaries, have twelve thousand in monthly recurring revenue growing eight percent a month and no hiring plan. The business is thinly profitable and cash is a buffer, not a lifeline. Load it to see how a lean team turns even small revenue into a positive month.
Scaling mid-market
A well-funded team scaling carefully
A company with three hundred thousand in recurring revenue has twenty-eight people, hires three a quarter and holds a large cash reserve. Revenue growth of seven percent covers the plan with a modest surplus. Load it to see how scale works only while growth and hiring stay in step.
Black-swan crisis
A big team on stalled growth
A startup with fourteen people and expensive salaries has thirty thousand in revenue growing half a percent a month, yet still plans two hires every quarter. Cash is limited. Load it to see burn outrun revenue and the runway shrink to a few months.
Industry benchmark matrix
| Metric | Danger zone | Industry average | Top 10% elite |
|---|---|---|---|
| Runway after a funding round | Below 9 months | 18–24 months | Above 30 months |
| Payroll as share of revenue | Above 85% | 50–70% | Below 50% |
| Monthly revenue growth (early stage) | Below 2% | 5–10% | Above 15% |
| Burn multiple (net burn ÷ new revenue) | Above 3 | 1.5–2 | Below 1 |
| Cost per hire beyond salary | Above 4 months of salary | 2–3 months | Under 1.5 months |
Variables and levers
Monthly recurring revenue
Recurring revenue you bill today, per month, before any growth.
Lever: Focus on retention and price before new channels, because every dollar of recurring revenue is worth more than a one-off sale.
Monthly revenue growth
Average month-on-month growth you expect over the next twelve months.
Lever: Fix the weakest step of the funnel rather than spending more, and measure growth after churn, not before.
Team size today
People on payroll now, including founders who draw a salary.
Lever: Hold headcount flat until revenue covers payroll with margin, because people are the largest and slowest cost to reverse.
Loaded cost per person
Monthly salary plus employer taxes and benefits for an average team member.
Lever: Mix cash and equity thoughtfully and avoid over-levelling early hires, since loaded cost compounds with every addition.
Hires per quarter
New people joining at the start of each quarter in your hiring plan.
Lever: Tie each hire to a revenue or cost milestone and slow the plan if growth lags behind it.
Cash in the bank
Current balance. It does not change this month's result; it decides how long a loss can last.
Lever: Extend runway with a bridge, venture debt or cost cuts early, since raising under pressure costs far more than raising with options.
How to use this simulator
- 1Enter your current recurring revenue, expected monthly growth and cash balance.
- 2Add the team size, the average loaded cost per person and the planned hires per quarter.
- 3Read the five boxes and note whether the cover ratio is above one.
- 4Press Find my breaking point to learn which assumption makes the month negative first.
- 5Compare the current plan with a hiring freeze and a price rise over 24 months.
Mistakes to avoid
- Planning hires on forecast growth. If revenue arrives later than expected, the payroll is already committed and the runway shortens twice over.
- Counting only salary. Recruiting, equipment, software and the weeks of reduced output from onboarding add up to a large share of a first-year cost.
- Looking at gross growth. Churn and discounts can erase new revenue, so use net recurring revenue.
- Waiting for six months of runway before acting. Raising or cutting under pressure leaves fewer options and worse terms than deciding at twelve.
Frequently asked questions
How is runway calculated here?
Cash divided by the monthly loss. If the average month is profitable, runway is shown as 120 months or more, since cash is not being consumed.
Why does the model average the next twelve months?
A single month hides the effect of growth and hiring. Averaging shows whether the whole year is sustainable, which is how most plans are judged.
Why is cash excluded from the stress test?
It does not change this month's result, so lowering it never worsens profit. It only changes how long a negative result can last.
Do I need to raise money?
Not necessarily. If the result is positive with room to spare, growth can be self-funded. If it is negative, the runway number tells you how long you have to raise, cut or change plan.
How do I find the breaking point?
Press Find my breaking point. The tool moves each input toward its worse end and reports the value where the monthly result reaches zero.
How accurate is this?
It is an educational model with stated assumptions, not financial advice. Use your own accounts and bank balance and update the inputs every month.
This is an educational planning model with stated assumptions. It is not financial, tax or legal advice. Replace the inputs with your own figures and verify important decisions with a qualified professional.