Skip to main content

Burn Rate & Runway Sensitivity Simulator

Model startup runway and burn rate with dynamic revenue/expense growth. Enter values for instant results with step-by-step formulas.

Share this calculator

Worked Examples

Example 1: Pre-Revenue Startup Crisis

Problem: Startup has $800K cash, $0 revenue, burning $120K/month (15 people × $8K loaded cost). No revenue growth yet. How long until broke?

Solution: Current State:\nCash: $800,000\nMonthly revenue: $0\nMonthly expenses: $120,000\nMonthly burn: $120,000\n\nCurrent Runway:\n$800K / $120K = 6.67 months\n\nThis is CRITICAL territory.\n\nProjection (no revenue change):\nMonth 0: $800K\nMonth 1: $680K\nMonth 2: $560K\nMonth 3: $440K\nMonth 4: $320K\nMonth 5: $200K\nMonth 6: $80K\nMonth 7: -$40K (BROKE)\n\nOptions:\n\n1. Cut burn to extend runway:\n Cut 5 people: $40K/month savings\n New burn: $80K/month\n New runway: $800K / $80K = 10 months\n \n2. Raise emergency bridge:\n $500K bridge extends by 4 months\n Buys time to hit milestones\n \n3. Generate revenue quickly:\n Need $30K revenue ASAP to buy time\n Consulting, services, anything cash-positive\n \nRecommendation:\nCombination:\n- Cut burn by 25% ($30K/month)\n- Gen

Result: 6.7 months runway (CRITICAL) | Must cut burn OR raise OR generate revenue | Combination approach best

Example 2: Growth-Stage Burn Analysis

Problem: SaaS company: $5M cash, $400K MRR, $600K monthly expenses, 10% revenue growth, 8% expense growth. Analyze runway and break-even path.

Solution: Current State:\nCash: $5,000,000\nRevenue: $400,000/month\nExpenses: $600,000/month\nBurn: $200,000/month\n\nCurrent Runway:\n$5M / $200K = 25 months\n\nProjection with Growth:\n\nMonth 0:\nRev: $400K, Exp: $600K, Burn: $200K, Cash: $5M\n\nMonth 6:\nRev: $400K × 1.10^6 = $709K\nExp: $600K × 1.08^6 = $952K\nBurn: $243K\nCash: $5M - (cumulative burn) ≈ $3.7M\n\nMonth 12:\nRev: $400K × 1.10^12 = $1,256K\nExp: $600K × 1.08^12 = $1,509K\nBurn: $253K\nCash: $5M - (cumulative) ≈ $2.1M\n\nProblem: Burn is INCREASING!\nRevenue growing 10%\nExpenses growing 8%\nBut starting from higher base ($600K vs $400K)\n\nBreak-even analysis:\nRevenue needs to catch expenses.\nRevenue growing faster (10% vs 8%)\n\nMonth when Rev = Exp:\n$400K × 1.10^n = $600K × 1.08^n\n1.10^n / 1.08^n = 1.5\n(1.10/1.08)^n = 1.5

Result: 25 months runway | Break-even month 22 | Should reach profitability | Monitor trajectory

Example 3: Expense Cut Scenario Planning

Problem: Startup: $1.2M cash, $50K revenue, $180K burn. Board asks for scenarios: 10% expense cut, 20% cut, 30% cut. What's the impact?

Solution: Base Case:\nCash: $1,200,000\nRevenue: $50,000\nExpenses: $230,000 (revenue + burn)\nBurn: $180,000\nRunway: $1.2M / $180K = 6.67 months\n\nScenario Analysis:\n\n10% Expense Cut:\nExpenses: $230K × 0.90 = $207K\nBurn: $207K - $50K = $157K\nRunway: $1.2M / $157K = 7.64 months\nGain: +0.97 months\n\n20% Expense Cut:\nExpenses: $230K × 0.80 = $184K\nBurn: $184K - $50K = $134K\nRunway: $1.2M / $134K = 8.96 months\nGain: +2.29 months\n\n30% Expense Cut:\nExpenses: $230K × 0.70 = $161K\nBurn: $161K - $50K = $111K\nRunway: $1.2M / $111K = 10.81 months\nGain: +4.14 months\n\nImpact Summary:\n10% cut = +1 month runway\n20% cut = +2.3 months\n30% cut = +4.1 months\n\nNon-linear: Each cut has bigger marginal impact.\n\n30% Cut Details:\nLikely means:\n- Cut 6-7 people (out of ~15-20)\n- Eliminate con

Result: Base: 6.7 months | 20% cut: 9 months (+2.3) | 30% cut: 10.8 months (+4.1) | Non-linear impact

Frequently Asked Questions

What is burn rate?

Burn rate is how much cash a company spends monthly beyond what it earns. If revenue is $100K and expenses are $300K, burn rate is $200K/month. Startups track burn rate obsessively as it determines survival time.

What is runway?

Runway is how long a company can operate before running out of cash, calculated as Cash ÷ Monthly Burn. With $2M cash and $200K burn, runway is 10 months. It's the most critical startup survival metric.

How much runway should a startup have?

Rule of thumb: 12-18 months minimum. Less than 12 months means immediate fundraising. Less than 6 months is crisis mode. Raising new funding typically takes 3-6 months, so start when 9-12 months remain.

What's a healthy burn multiple?

Burn multiple = Net Burn ÷ Net New ARR. Under 1.5x is excellent (efficient growth). 1.5-3x is good. Above 3x is concerning—burning too much per dollar of growth. Top SaaS companies achieve <1.5x.

Should I reduce burn or increase revenue?

Depends on stage. Pre-product/market fit: burning for growth may be premature; find fit first. Post-PMF: burn to grow is justified if unit economics work. Always easier to cut costs than grow revenue quickly.

How do I extend runway without raising capital?

Options: cut discretionary expenses, reduce headcount, renegotiate vendor contracts, delay non-critical initiatives, increase prices, accelerate collections, or sell assets. Emergency measures include: founder salary cuts or bridge loans.

Background & Theory

The Burn Rate & Runway Sensitivity Simulator applies the following established principles and formulas. Finance and investing rest on the foundational concept of the time value of money: a dollar received today is worth more than a dollar received in the future, because present funds can be deployed to earn a return. This principle underlies virtually every valuation technique in modern finance. The future value of a present sum P growing at rate r over n periods is expressed as FV = P(1 + r)^n, while the present value of a future cash flow FV is PV = FV / (1 + r)^n. Compound growth amplifies returns significantly over long horizons, a dynamic often described as the eighth wonder of the world. Net Present Value (NPV) extends these mechanics to evaluate investment projects by summing the present values of all expected cash flows minus the initial outlay: NPV = sum[CF_t / (1 + r)^t] - C_0. A positive NPV indicates the project creates value above the required return. The Internal Rate of Return (IRR) is the discount rate that sets NPV to zero, providing a single percentage benchmark for project comparison. The risk-return tradeoff is the central tension of investment theory. Higher expected returns generally require accepting greater uncertainty. Harry Markowitz formalized this in Modern Portfolio Theory by demonstrating that portfolio variance can be reduced through diversification when assets are imperfectly correlated. The efficient frontier represents the set of portfolios offering the maximum return for a given level of risk. The Capital Asset Pricing Model (CAPM) extends this by introducing the market portfolio as a reference, defining expected return as E(r) = r_f + beta * (E(r_m) - r_f), where beta measures an asset's sensitivity to systematic market risk. Asset classes — equities, fixed income, real assets, and alternatives — differ in their return profiles, liquidity, and correlations. Strategic asset allocation determines long-run target weights based on investor objectives and risk tolerance, while tactical allocation permits short-run deviations to exploit perceived mispricings. Discount rates used in valuation models must reflect the cost of capital appropriate to the risk of the cash flows being discounted, a point stressed in corporate finance texts from Brealey, Myers, and Allen through to Damodaran.

History

The history behind the Burn Rate & Runway Sensitivity Simulator traces back through the following developments. The formal practice of lending at interest dates to ancient Mesopotamia, where the Code of Hammurabi around 1750 BCE regulated interest rates on grain and silver loans. Banking as an institutional activity took root in medieval Italy, with merchant bankers in Florence and Venice financing trade across Europe through instruments such as bills of exchange. The Medici family operated one of the most sophisticated banking networks of the fifteenth century, pioneering double-entry bookkeeping and correspondent banking relationships. Organized equity markets emerged in the early seventeenth century. The Dutch East India Company (VOC), chartered in 1602, issued shares to the public and created the Amsterdam Stock Exchange — widely regarded as the world's first formal stock exchange. The VOC allowed investors to buy and sell shares freely, establishing the template for the joint-stock company. The period also produced the Dutch tulip mania of 1636 to 1637, one of history's first recorded speculative bubbles, in which tulip bulb futures contracts reached extraordinary prices before collapsing. England's financial revolution followed in the late seventeenth century with the founding of the Bank of England in 1694 and the development of government bond markets. The South Sea Bubble of 1720 illustrated the dangers of speculative excess and contributed to early securities regulation. Throughout the eighteenth and nineteenth centuries, industrialization created enormous demand for capital, fueling the expansion of stock exchanges in London, Paris, New York, and beyond. The New York Stock Exchange, formalized in 1817, became the world's dominant equities market by the twentieth century. The Great Crash of 1929 and subsequent Great Depression prompted the US Securities Act of 1933 and Securities Exchange Act of 1934, establishing the SEC and mandatory disclosure requirements. Harry Markowitz published his landmark portfolio selection paper in 1952, launching quantitative finance. The CAPM emerged in the 1960s through work by Sharpe, Lintner, and Mossin. John Bogle launched the first retail index fund in 1976, democratizing diversified investing and challenging active management orthodoxy.

References