Runway Math for Your First 90 Days: Plan Your Solo Cash Flow

The first 90 days as a solo are less about growth and more about not running out of money while you find your footing.

This guide shows you how to calculate runway, model realistic scenarios, and make financial decisions that maximize your time to profitability.

Disclaimer: This is general financial planning information, not professional financial advice. Your situation is unique - adjust accordingly.

The Core Concept: Runway

Runway = How long you can operate before running out of cash

The formula is simple:

Cash on hand ÷ Monthly burn rate = Months of runway

Why this matters: Runway determines your decision-making timeline. Four months of runway means different choices than twelve months.

Understanding your runway lets you:

• Set realistic revenue goals
• Decide when to take risks vs. play it safe
• Know when to pivot or extend runway
• Avoid panic-driven decisions

Step 1: Calculate Your Monthly Burn Rate

Personal Expenses (The Non-Negotiables)

Core living expenses:

• Housing (rent/mortgage, utilities, insurance)
• Food and groceries
• Transportation (car payment, insurance, gas, transit)
• Health insurance and medical
• Debt payments (student loans, credit cards, etc.)
• Phone and internet (personal portion)
• Childcare (if applicable)

Total core: $________/month

Discretionary (can be cut if needed):

• Dining out and entertainment
• Subscriptions (streaming, apps, etc.)
• Gym and fitness
• Shopping and personal care
• Travel and hobbies

Total discretionary: $________/month

Total personal expenses: $________/month

Business Expenses (The Essentials)

Fixed monthly costs:

• Software and tools (essential only)
• Internet and phone (business portion)
• Email and hosting
• Banking fees
• Insurance (liability, E&O if needed)
• Coworking or office (if applicable)
• Bookkeeping/accounting

Total fixed: $________/month

Variable costs:

• Contract labor and freelancers
• Marketing and advertising
• Travel and client meetings
• Professional development
• Miscellaneous supplies

Total variable (average): $________/month

Total business expenses: $________/month

Total Monthly Burn

Personal expenses: $________
Business expenses: $________
Total burn rate: $________/month

Example:

Personal: $4,000/month
Business: $1,000/month
Total burn: $5,000/month

Step 2: Calculate Current Runway

Your current cash:

• Personal savings: $________
• Business account: $________
• Emergency fund (keep separate): $________
• Available credit (only if desperate): $________

Total available: $________

Runway calculation:

Available cash ÷ Monthly burn = Months of runway

Example:

$30,000 ÷ $5,000 = 6 months runway

Runway Health Check

3 months or less: Red zone (high pressure, need revenue immediately)

4-6 months: Yellow zone (workable but tight, focus on quick wins)

7-12 months: Green zone (healthy, can be strategic)

12+ months: Blue zone (excellent, can take bigger bets)

Where are you? _________ months

Step 3: Model Your First 90 Days

Realistic Revenue Scenarios

Don't plan for best-case. Plan for realistic, conservative, and worst-case.

Scenario 1: Optimistic (30% probability)

Month 1 revenue: $________
Month 2 revenue: $________
Month 3 revenue: $________
Total: $________

Scenario 2: Realistic (50% probability)

Month 1 revenue: $________
Month 2 revenue: $________
Month 3 revenue: $________
Total: $________

Scenario 3: Conservative (80% probability)

Month 1 revenue: $________
Month 2 revenue: $________
Month 3 revenue: $________
Total: $________

Pro tip: Plan for the conservative scenario. If reality lands between realistic and optimistic, that's a bonus.

Common First-90-Days Revenue Patterns

Pattern 1: Pre-Sold (Ideal)

• Month 1: $8,000 (existing client/retainer)
• Month 2: $8,000 (same)
• Month 3: $10,000 (added second client)
• Total: $26,000

Best for: Advisors with existing relationships

Pattern 2: Ramping Builder

• Month 1: $0 (building)
• Month 2: $500 (first beta customers)
• Month 3: $2,000 (growing user base)
• Total: $2,500

Best for: Product builders, SaaS, indie hackers

Pattern 3: Project-Based

• Month 1: $0 (prospecting and closing)
• Month 2: $5,000 (first project milestone)
• Month 3: $5,000 (completion + new project deposit)
• Total: $10,000

Best for: Agencies, freelancers, designers

Pattern 4: Local SMB

• Month 1: $3,000 (quick first clients)
• Month 2: $5,000 (word of mouth + referrals)
• Month 3: $7,000 (building local presence)
• Total: $15,000

Best for: Service businesses, trades, local consultants

Which pattern fits your model? _______________

Step 4: Calculate Net Cash Position

Month-by-Month Projection

Starting position:

• Cash on hand: $________

Month 1:

Starting cash: $________
Revenue: $________
Expenses: $________
Ending cash: $________ (starting + revenue - expenses)
Runway remaining: ________ months

Month 2:

Starting cash: $________
Revenue: $________
Expenses: $________
Ending cash: $________
Runway remaining: ________ months

Month 3:

Starting cash: $________
Revenue: $________
Expenses: $________
Ending cash: $________
Runway remaining: ________ months

The Critical Question

After 90 days:

• Do you have more or less cash than you started with?
• How many months of runway remain?
• Are you trending toward profitability or depletion?

If your runway is shrinking: You need to either increase revenue or decrease expenses - fast.

Step 5: Identify Your Break-Even Point

Break-even = Revenue equals expenses

Your numbers:

Monthly burn rate: $________
Target monthly revenue: $________
Gap to close: $________

Example:

Monthly burn: $5,000
Current revenue: $2,000
Gap: $3,000/month needed

Revenue Required by Pricing Model

If you charge hourly:

Gap ÷ Hourly rate = Hours needed

Example: $3,000 ÷ $150/hour = 20 hours/month

If you charge per project:

Gap ÷ Project price = Projects needed

Example: $3,000 ÷ $1,500/project = 2 projects/month

If you charge retainers:

Gap ÷ Monthly retainer = Clients needed

Example: $3,000 ÷ $3,000/client = 1 client

If you charge subscriptions (MRR):

Gap ÷ Monthly price = Customers needed

Example: $3,000 ÷ $50/month = 60 customers

What do you need to break even? ________________

Is that realistic in 90 days? Yes / No

If no, what needs to change?

• Lower burn rate? (cut expenses)
• Increase pricing? (charge more)
• Change model? (retainers instead of projects)
• Extend timeline? (plan for 6 months instead of 3)

Step 6: Build Your Contingency Plans

Plan A: Ideal Scenario

What needs to happen:

• Revenue ramps as projected
• Expenses stay within budget
• Runway extends or stabilizes

Key milestones:

• Month 1: $________ revenue (target)
• Month 2: $________ revenue (target)
• Month 3: $________ revenue (target)

Plan B: Slower Revenue Ramp

Trigger: Revenue is 50% below target after Month 1

Actions:

• Cut discretionary personal expenses by 30%
• Pause non-essential business expenses
• Take on additional consulting/freelance work
• Accelerate sales outreach (double activity)
• Consider part-time work to extend runway

Extended runway: ________ months

Plan C: No Revenue in First 60 Days

Trigger: Zero or minimal revenue after two months

Actions:

• Cut personal expenses to bare minimum
• Freeze all non-essential business spending
• Take contract work or part-time job immediately
• Revisit business model (product-market fit issue?)
• Consider returning to full-time work temporarily

This is not failure - it's smart risk management.

Plan D: Unexpected Expense or Emergency

Trigger: Major unexpected cost (medical, equipment failure, etc.)

Actions:

• Tap emergency fund (keep separate from business cash)
• Negotiate payment plans for large expenses
• Temporarily pause business investment
• Accelerate revenue (discount, special offer, fast cash)

Buffer needed: $________ (3-6 months personal expenses, separate)

Step 7: Strategies to Extend Runway

Decrease Burn (Faster Results)

Personal expenses:

• Move to lower cost-of-living area (saves $500-1,500/month)
• Eliminate subscriptions and discretionary spending (saves $200-500/month)
• Negotiate rent, insurance, or recurring bills (saves $100-300/month)
• Downsize housing temporarily (saves $300-1,000/month)

Business expenses:

• Use free tools instead of paid (saves $100-500/month)
• Cancel unused software (saves $50-200/month)
• Work from home instead of coworking (saves $200-500/month)
• DIY instead of outsourcing (saves $200-1,000/month)

Total potential savings: $________ /month

Extended runway: ________ months (recalculate)

Increase Cash (Slower but Powerful)

Quick cash sources:

• Pre-sell services or products (deposit/retainer model)
• Consulting or freelance work (immediate income)
• Sell unused equipment or assets
• Negotiate faster payment terms with clients (NET 15 instead of NET 30)

Longer-term sources:

• Part-time or contract work (steady income while building)
• Friends and family investment (rare for solos, but possible)
• Small business loan or line of credit (use cautiously)

Potential added cash: $________

Step 8: Set 30/60/90 Day Milestones

Month 1 (Days 1-30)

Revenue goal: $________

Cash position goal: $________

Key actions:

• _________________________________
• _________________________________
• _________________________________

Success metric: ___________________________

Month 2 (Days 31-60)

Revenue goal: $________

Cash position goal: $________

Key actions:

• _________________________________
• _________________________________
• _________________________________

Success metric: ___________________________

Month 3 (Days 61-90)

Revenue goal: $________

Cash position goal: $________

Key actions:

• _________________________________
• _________________________________
• _________________________________

Success metric: ___________________________

Review Checkpoint (End of Month 1)

Questions to ask:

1. Did I hit my revenue target? If not, why?
2. Were my expenses accurate or off?
3. Is my runway better or worse than projected?
4. Do I need to activate Plan B or C?
5. What do I need to change for Month 2?

Set a calendar reminder to review these on Day 30.

Real Scenarios: What This Looks Like

Scenario 1: Fractional with Pre-Sold Client

Starting position:

• Cash: $40,000
• Monthly burn: $6,000
• Starting runway: 6.7 months

Revenue plan:

• Month 1: $8,000 (existing retainer)
• Month 2: $8,000 (same)
• Month 3: $12,000 (added client)

Outcome after 90 days:

Starting cash: $40,000
Total revenue: $28,000
Total expenses: $18,000
Ending cash: $50,000
Runway: 8.3 months (improved)

Result: Healthy growth, extended runway, can invest in marketing.

Scenario 2: Solo Builder with No Revenue

Starting position:

• Cash: $20,000
• Monthly burn: $4,000
• Starting runway: 5 months

Revenue plan:

• Month 1: $0 (building MVP)
• Month 2: $0 (beta testing)
• Month 3: $500 (first paying users)

Outcome after 90 days:

Starting cash: $20,000
Total revenue: $500
Total expenses: $12,000
Ending cash: $8,500
Runway: 2.1 months (critical)

Result: Runway depleted, needs Plan B immediately (part-time work or consulting).

Scenario 3: Agency Starting from Scratch

Starting position:

• Cash: $25,000
• Monthly burn: $5,000
• Starting runway: 5 months

Revenue plan:

• Month 1: $2,000 (small first client)
• Month 2: $6,000 (two projects)
• Month 3: $8,000 (ramping pipeline)

Outcome after 90 days:

Starting cash: $25,000
Total revenue: $16,000
Total expenses: $15,000
Ending cash: $26,000
Runway: 5.2 months (stable)

Result: Approaching break-even, needs to maintain momentum.

Scenario 4: Local SMB with Fast Traction

Starting position:

• Cash: $15,000
• Monthly burn: $4,500
• Starting runway: 3.3 months

Revenue plan:

• Month 1: $4,000 (quick local clients)
• Month 2: $6,000 (word of mouth)
• Month 3: $7,500 (growing reputation)

Outcome after 90 days:

Starting cash: $15,000
Total revenue: $17,500
Total expenses: $13,500
Ending cash: $19,000
Runway: 4.2 months (improved)

Result: Profitable, runway extending, can reinvest.

Which scenario looks most like your situation? _______________

The Weekly Cash Review (15 Minutes)

Every Monday, check:

1. Cash position: How much is in the bank?
2. Revenue this week: What came in?
3. Expenses this week: What went out?
4. Runway: How many months left?
5. Next week's plan: What needs to happen?

Template:

Week of: _________
Starting cash: $________
Revenue: $________
Expenses: $________
Ending cash: $________
Runway: ________ months
Status: On track / Need adjustment / Activate Plan B

This 15-minute habit prevents surprises.

Common Runway Mistakes (Avoid These)

1. Optimistic revenue projections

• Planning for best-case instead of realistic
• Not accounting for sales cycles and delays
• Assuming instant traction

2. Underestimating expenses

• Forgetting small recurring costs
• Not budgeting for taxes (30% of revenue)
• Ignoring one-time setup costs

3. No contingency plan

• Only having Plan A
• No trigger points for action
• Waiting too long to adjust

4. Burning runway on non-essentials

• Expensive tools before product-market fit
• Office space when home works fine
• Marketing spend before offer validation

5. Not tracking weekly

• Reviewing only monthly or quarterly
• Missing early warning signs
• Reacting too late

6. Mixing emergency fund and business cash

• No personal safety net
• Business failure threatens personal stability

7. Ignoring the break-even math

• Not knowing how much revenue is needed
• Unrealistic customer acquisition assumptions

Tools to Track Runway

Spreadsheet (Free):

• Google Sheets or Excel
• Create your own tracker (sample above)
• Update weekly

Bookkeeping Software:

• QuickBooks (cash flow reports)
• Xero (cash flow dashboard)
• Wave (free basic reports)

Specialized Tools:

• Runway (financial planning for startups)
• Finmark (financial modeling and forecasting)
• Causal (scenario planning)

Recommended for most solos: Simple spreadsheet + weekly review.

Your Action Plan

This week:

1. Calculate your monthly burn rate (personal + business)
2. Calculate your current runway
3. Model three revenue scenarios (optimistic, realistic, conservative)
4. Project your 90-day cash position

Next week: 5. [ ] Identify your break-even revenue target 6. [ ] Create Plan B and Plan C (contingencies) 7. [ ] Set 30/60/90 day milestones 8. [ ] Schedule weekly cash reviews (Monday mornings)

Next 90 days: 9. [ ] Track actual vs. projected every week 10. [ ] Adjust plans based on reality 11. [ ] Activate contingency plans if needed 12. [ ] Celebrate if you extend runway

The Bottom Line

Runway is not about predicting the future. It's about knowing your options.

More runway = more time to find product-market fit = better decisions.

The math is simple:

1. Know your burn rate
2. Track your cash weekly
3. Model realistic scenarios
4. Have contingency plans
5. Adjust based on reality

Most solos fail not because the idea was bad, but because they ran out of money before finding the right fit.

Don't let that be you.

Know your numbers. Plan conservatively. Execute relentlessly.

Your runway is your most valuable asset. Protect it.

---

Ready to set up your full finance stack? Read our Solo Finance Setup guide for banking, bookkeeping, and taxes.

Need to choose the right entity structure? Check out our Tax Checklist by Entity Type.

Want help with your bookkeeping tools? See our Bookkeeping Stack for Solos comparison.

Need help calculating your baseline pricing? Try our Early Pricing Calculator to model your rates.

Want weekly finance tips and runway tracking reminders? Join our newsletter for cash flow strategies, planning templates, and real solo finance stories.