Burn Rate and Cash Runway Analysis: Managing Your Company's Lifespan
Master burn rate and runway. Calculate how long your cash will last, understand burn drivers, and plan your path to profitability or next funding round.
Key Takeaways
- Burn rate definition: Monthly cash spent (cash outflow minus inflow). Formula: (Starting cash - Ending cash) / Month count = monthly burn. Example: Jan £100K cash, Feb £80K = £20K monthly burn. At £20K/month, £100K runway = 5 months until zero cash (critical!). Key: Track actual burn monthly, project runway quarterly. Runway = Current cash / Monthly burn rate.
- Profitability math: Monthly revenue £100K, monthly costs £120K = £20K monthly burn (unprofitable). To break even: Either increase revenue 20% to £120K (hard), or cut costs 17% to £100K (easier). Path: Show board when breakeven (month 24?), what needs to change (revenue growth, cost cuts).
- Runway sensitivity: Starting cash £500K, monthly burn £30K = 16.7 month runway. But burn increases: Month 6 burn £35K → 14.3 month runway (recalculate). Sensitivity: Each 10% burn increase = 10-15% runway reduction. Monthly forecasting: Actual burn vs budget, adjust runway forecast.
Understanding Burn Rate
Calculating and tracking cash consumption. **Burn Rate Definition** Burn rate: Amount of cash company spends monthly. Formula: (Starting cash balance - Ending cash balance) / Months = Monthly burn Example month: - Jan 1 cash: £100K - Jan 31 cash: £80K - Monthly burn: (£100K - £80K) / 1 = £20K **Simple Burn Calculation** Monthly P&L to cash burn: | Item | Amount | |------|--------| | Revenue | £50K | | COGS | -£10K | | Gross Profit | £40K | | Operating Expenses | -£60K | | Operating Loss | -£20K | | + Non-cash charges | £0 | | **Net Monthly Cash Burn** | **£20K** | Interpretation: Company spends £20K more cash than it receives monthly. **Runway Calculation** Runway: How many months until cash hits zero. Formula: Current cash balance / Monthly burn rate = Months of runway Example: - Current cash: £100K - Monthly burn: £20K - Runway: £100K / £20K = 5 months Critical: At 5 months runway, need to either: 1. Reach profitability (zero burn) 2. Raise funding (increase cash) 3. Cut costs (reduce burn) **Burn Trajectory** Burn rate changes over time (usually increases as company grows): | Month | Headcount | Monthly Burn | Cumulative Burn | Remaining Cash | |-------|-----------|---|---|---| | Jan | 5 | £20K | £20K | £80K | | Feb | 6 | £22K | £42K | £58K | | Mar | 7 | £24K | £66K | £34K | | Apr | 8 | £26K | £92K | £8K | | May | - | - | - | ZERO (ran out) | Insight: Company out of cash in May if burn continues increasing. **Fixed vs Variable Burn** Fixed burn (doesn't scale): - Salaries, rent, tools - Example: £15K/month fixed Variable burn (scales with growth): - Sales commissions, hosting costs - Example: 5% of revenue Total burn = Fixed + Variable If revenue growing, variable burn increases → total burn increases.
Profitability Path
Planning the journey to cash-positive. **Unprofitable → Profitable Transition** Current state: Unprofitable (burning cash). Example: - Monthly revenue: £100K - Monthly costs: £120K - Monthly burn: £20K To reach profitability (zero burn): Option A: Grow revenue 20% → £120K revenue, break even - Challenge: Market conditions, sales capacity - Timeline: 6-12 months realistic Option B: Cut costs 17% → £100K costs, break even - Easier: Reduce hiring, eliminate projects, negotiate vendor costs - Timeline: Immediate (1-3 months) Option C: Balanced approach - Grow revenue 10% → £110K - Cut costs 8.3% → £110K - Timeline: 6 months **Unit Economics Path** Improve profitability by improving unit economics: Current: - CAC: £4K - LTV: £60K - LTV/CAC: 15x (healthy) - But: Current burn £20K because of heavy sales/marketing spend Option: Shift to lower CAC channel - Current: £200K S&M spend → 50 customers - New: £150K S&M spend → 40 customers (20% less spend, 20% fewer customers) - Burn: £20K → £15K (25% reduction) - Runway improves from 5 months to 6.7 months Trade-off: Slower growth for longer runway. **Profitability Timeline** Build a roadmap: | Quarter | Revenue | Costs | Burn | Cumulative Burn | Cash Remaining | |---------|---------|-------|------|---|---| | Q1 (now) | £100K | £120K | £20K | £60K | £40K | | Q2 | £120K | £130K | £10K | £90K | £10K | | Q3 | £150K | £150K | £0K | £90K | £10K | | Q4 | £180K | £160K | -£20K | £70K | £30K | Timeline: Break even Q3, profitable Q4. But tight — if Q2 misses, out of cash. Better strategy: Build profitability buffer by raising funding or cutting earlier.
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Start for free →Burn Rate Management
Controlling and forecasting burn. **Monthly Burn Tracking** Track actual burn vs budget: | Month | Budgeted Burn | Actual Burn | Variance | |-------|---|---|---| | Jan | £20K | £20K | On track | | Feb | £20K | £22K | +£2K (2% overspend) | | Mar | £20K | £24K | +£4K (4% overspend) | Insight: Actual burn trending higher. Reasons: - Hiring ahead of schedule - Tool costs higher than expected - Revenue lower than forecast (burn %, not absolute) Action: Investigate overspend, adjust forecast. **Controllable Burn Levers** Variable costs (can reduce): - Sales commissions: 5% of revenue → cut to 4% (£5K savings if £100K revenue) - Hosting costs: Optimize infrastructure → 10% savings (£1K savings) - Contractors/agencies: Reduce spending → £2K savings - Total potential: £8K savings (40% burn reduction) Fixed costs (harder to reduce): - Salaries: Cut headcount or freeze hiring (3 month delay = £15K savings) - Rent: Renegotiate or move office (costly, slow) - Tools: Consolidate, cancel unused (£1K savings) - Total potential: £16K savings (80% burn reduction) Strategy: Variable cost cuts first (fastest). Fixed cost cuts if critical. **Runway Sensitivity Analysis** Base case: £100K cash, £20K burn = 5 month runway Scenarios: Optimistic: - Revenue +30% → burn £10K (only variable costs) - Runway: £100K / £10K = 10 months Pessimistic: - Revenue -20% → burn £30K (fixed costs remain) - Runway: £100K / £30K = 3.3 months Insight: Revenue changes impact runway significantly. **Burn Forecast Updates** Update runway quarterly: Q1 actual: £100K opening, £60K closing = £40K burn (£20K/month) Q2 forecast: Assuming £50K monthly burn (higher due to hiring) - Remaining: £40K - Q2 projected close: £40K - £150K burn = NEGATIVE (problem!) - Action: Cut burn by 30% or raise funding before Q2 starts Time-sensitivity: Update forecasts early, act before crisis.
Planning for Profitability
Building the path to sustainability. **Profitability Scenarios** Scenario 1: Revenue growth (path up) - Current: £100K revenue, £120K costs - Month 6: £150K revenue, £130K costs (profitable!) - Requires: Sales capacity, market demand, execution Scenario 2: Cost reduction (path down) - Current: £100K revenue, £120K costs - Month 3: £100K revenue, £100K costs (profitable!) - Requires: Difficult decisions (cut headcount, eliminate projects) Scenario 3: Funding + time (path forward) - Raise £300K funding in month 2 - Use to extend runway to 15 months - Target: Reach profitability month 8-12 - Requires: Investor support, clear path to profitability Most realistic: Combination - Grow revenue (20% → £120K) - Cut costs (8% → £110K) - Raise small round (£200K) - Timeline: Profitable month 12 **Runway vs Profitability Trade-off** Conservative (protect runway): - Slow hiring (extend runway longer) - Cut aggressive experiments - Improve unit economics first - Result: 12+ month runway, slower growth Aggressive (go for growth): - Hire fast (reduce runway) - Invest in marketing (burn faster) - Bet on revenue growth - Result: Shorter runway (6-8 months), faster growth Best approach: Start conservative (build runway buffer), turn aggressive once unit economics prove. **Communication to Board/Investors** Show profitability path clearly: "Path to profitability: - Current: £100K MRR, unprofitable (£20K monthly burn) - Target: Profitability by Q4 2024 (month 9) - Strategy: 1. Grow revenue 50% (£150K MRR by month 9) 2. Maintain costs flat (ops efficiency) 3. Result: Profitable at £150K MRR - Risk: Revenue growth misses, churn increases - Mitigation: Cost cuts prepared if revenue targets missed" Clear roadmap builds investor confidence.