Saas Economics Efficiency Metrics by @deanpeters · Skillet
Why PMs care: A feature that generates $1M revenue at 80% margin is worth far more than $1M at 30% margin. Margin determines which features to prioritize.Formula: (Revenue - COGS) / Revenue × 100COGS includes: Hosting, infrastructure, payment processing, customer onboarding costsBenchmark: SaaS 70-85% good; <60% concerning CAC (Customer Acquisition Cost) — Total cost to acquire one customer.
Why PMs care: Shapes entire go-to-market strategy. Determines which channels are viable and how much you can invest in product-led growth.Formula: Total Sales & Marketing Spend / New Customers AcquiredBenchmark: Varies by model—Enterprise $10K+ ok; SMB <$500 targetInclude: Marketing spend, sales salaries, tools, commissions LTV (Lifetime Value) — Total revenue expected from one customer over their lifetime.
Why PMs care: Tells you what you can afford to spend on acquisition. Higher LTV enables premium channels and longer payback periods.Formula (simple): ARPU × Average Customer Lifetime (months)Formula (better): ARPU × Gross Margin % / Churn RateFormula (advanced): Account for expansion, discount rates, cohort-specific retentionBenchmark: Must be 3x+ CAC; varies by segment LTV:CAC Ratio — Efficiency of customer acquisition spending.
Why PMs care: Is growth sustainable or are you buying revenue at a loss? Determines when to scale vs. optimize.Formula: LTV / CACBenchmark: 3:1 healthy; <1:1 unsustainable; >5:1 might be underinvestingNote: This ratio alone doesn't tell the full story—also need payback period Payback Period — Months to recover CAC from customer revenue.
Why PMs care: Cash efficiency. Faster payback = reinvest sooner. Slow payback can kill growth even with good LTV:CAC.Formula: CAC / (Monthly ARPU × Gross Margin %)Benchmark: <12 months great; 12-18 ok; >24 months concerningCritical: Must have cash to sustain payback period Contribution Margin — Revenue remaining after ALL variable costs (not just COGS).
Why PMs care: True unit profitability. Includes support, processing fees, variable OpEx.Formula: (Revenue - All Variable Costs) / Revenue × 100Variable costs: COGS + support + payment processing + variable customer successBenchmark: 60-80% good for SaaS; <40% concerning Gross Margin Payback — Payback period using actual profit, not revenue.
Why PMs care: More accurate than simple payback. Shows true cash recovery time.Formula: CAC / (Monthly ARPU × Gross Margin %)Benchmark: Typically 1.5-2x longer than simple revenue payback CAC Payback by Channel — Compare payback across acquisition channels.
Why PMs care: Not all channels are created equal. Optimize channel mix based on payback efficiency.Formula: Calculate CAC and payback separately for each channelUse: Allocate budget to faster-payback channels when cash-constrained
Capital Efficiency Family Metrics that measure how efficiently you use cash to grow the business.
Burn Rate — Cash consumed per month.
Why PMs care: Determines what you can build and when you need funding. High burn requires aggressive revenue growth.Formula (Gross Burn): Monthly Cash Spent (all expenses)Formula (Net Burn): Monthly Cash Spent - Monthly RevenueBenchmark: Net burn <$200K manageable for early stage; >$500K needs clear path to revenue Runway — Months until cash runs out.
Why PMs care: Literal survival metric. Dictates timeline for milestones, fundraising, profitability.Formula: Cash Balance / Monthly Net BurnBenchmark: 12+ months good; 6-12 manageable; <6 months crisis modeRule: Raise when you have 6-9 months runway, not 3 months OpEx (Operating Expenses) — Costs to run the business (excluding COGS).
Why PMs care: Your team's salaries live here. Where "efficiency" cuts happen during downturns.Categories: Sales & Marketing (S&M), Research & Development (R&D), General & Administrative (G&A)Benchmark: Should grow slower than revenue as you scale (operating leverage) Net Income (Profit Margin) — Actual profit or loss after all expenses.
Why PMs care: True bottom line. Are you making money? Can you self-fund growth?Formula: Revenue - All Expenses (COGS + OpEx)Benchmark: Early SaaS often negative (growth mode); mature should be 10-20%+ margin Working Capital Impact — Cash timing differences between revenue recognition and cash collection.
Why PMs care: Annual contracts paid upfront boost cash. Monthly billing delays cash. Affects runway calculations.Example: $1M annual contract paid upfront = $1M cash now, not $83K/monthUse: Understand cash vs. revenue timing when planning runway
Efficiency Ratios Family Composite metrics that measure growth vs. profitability trade-offs.
Rule of 40 — Growth rate + profit margin should exceed 40%.
Why PMs care: Framework for balancing growth vs. efficiency. Guides when to prioritize profitability over growth.Formula: Revenue Growth Rate % + Profit Margin %Benchmark: >40 healthy; 25-40 acceptable; <25 concerningExample: 60% growth + (-20%) margin = 40 (healthy growth-mode SaaS)Example: 20% growth + 25% margin = 45 (healthy mature SaaS) Magic Number — Sales & marketing efficiency.
Why PMs care: Is your GTM engine working? Should you scale spend or optimize first?Formula: (Current Quarter Revenue - Previous Quarter Revenue) × 4 / Previous Quarter S&M SpendBenchmark: >0.75 efficient; 0.5-0.75 ok; <0.5 fix before scalingNote: "× 4" annualizes quarterly revenue change Operating Leverage — How revenue growth compares to cost growth.
Why PMs care: Are you scaling efficiently? Revenue should grow faster than costs.Measure: Revenue growth rate vs. OpEx growth rate over timeGood: Revenue growth 50%, OpEx growth 30% (positive leverage)Bad: Revenue growth 20%, OpEx growth 40% (negative leverage) Unit Economics — General term for profitability of each "unit" (customer, seat, transaction).
Why PMs care: Is the business model fundamentally viable at the unit level?Calculate: Revenue per unit - Cost per unitRequirement: Positive contribution required; aim for >$0 after all variable costs
Anti-Patterns (What This Is NOT)
Not vanity metrics: High LTV means nothing if payback takes 4 years and customers churn at 3 years.Not static benchmarks: "Good" CAC varies wildly by business model (PLG vs. enterprise sales).Not isolated numbers: LTV:CAC ratio without payback period can mislead (great ratio, terrible cash efficiency).Not just finance's problem: PMs must own unit economics—every feature decision impacts margins and CAC.
When to Use These Metrics
Evaluating whether to scale acquisition (LTV:CAC, payback, magic number)
Deciding feature investments (margin impact, contribution to LTV)
Planning runway and fundraising (burn rate, runway, Rule of 40)
Comparing customer segments or channels (unit economics by segment)
Board/investor reporting (Rule of 40, magic number, LTV:CAC)
Choosing between growth and profitability (Rule of 40 trade-offs)
Making decisions without revenue context (pair with saas-revenue-growth-metrics)
Comparing across wildly different business models without normalization
Early product discovery (pre-revenue focus on PMF, not unit economics)
Short-term tactical decisions (use engagement metrics, not LTV)
Application
Step 1: Calculate Unit Economics Use the templates in template.md to calculate your unit economics metrics.
Gross Margin Gross Margin = (Revenue - COGS) / Revenue × 100
COGS includes:
- Hosting & infrastructure costs
- Payment processing fees
- Customer onboarding costs
- Direct delivery costs
Revenue: $1,000,000
COGS: $200,000 (hosting $120K, processing $50K, onboarding $30K)
Gross Margin = ($1M - $200K) / $1M = 80%
Is gross margin improving as you scale? (Should benefit from economies of scale)
Which products/features have highest margins? (Prioritize those)
Are margins >70%? (SaaS should be high-margin)
CAC (Customer Acquisition Cost) CAC = Total Sales & Marketing Spend / New Customers Acquired
Include in S&M spend:
- Marketing salaries & tools
- Sales salaries & commissions
- Advertising & paid channels
- SDR/BDR team costs
Sales & Marketing Spend: $500,000/month
New Customers: 100/month
CAC = $500,000 / 100 = $5,000
Is CAC consistent across channels? (Calculate by channel)
Is CAC increasing or decreasing over time? (Should decrease with scale)
Does CAC vary by customer segment? (SMB vs. Enterprise)
LTV (Lifetime Value) LTV (Simple) = ARPU × Average Customer Lifetime (months)
LTV (Better) = ARPU × Gross Margin % / Monthly Churn Rate
LTV (Advanced) = Account for expansion, cohort-specific retention, discount rate
ARPU: $500/month
Average Lifetime: 36 months
LTV = $500 × 36 = $18,000
ARPU: $500/month
Gross Margin: 80%
Monthly Churn: 2%
LTV = ($500 × 80%) / 2% = $400 / 0.02 = $20,000
Is LTV growing over time? (From expansion, improved retention)
Does LTV vary by cohort? (Are new customers more/less valuable?)
Does LTV vary by segment? (Enterprise vs. SMB)
LTV:CAC Ratio LTV:CAC Ratio = LTV / CAC
LTV: $20,000
CAC: $5,000
LTV:CAC = $20,000 / $5,000 = 4:1
Is ratio >3:1? (Minimum for sustainable growth)
Is ratio >5:1? (Might be underinvesting in growth)
Is ratio improving or degrading over time?
<1:1 = Losing money on every customer (unsustainable)1-3:1 = Marginal economics (optimize before scaling)3-5:1 = Healthy (scale confidently)>5:1 = Potentially underinvesting (could grow faster)
Payback Period Payback Period (months) = CAC / (Monthly ARPU × Gross Margin %)
CAC: $5,000
Monthly ARPU: $500
Gross Margin: 80%
Payback = $5,000 / ($500 × 80%) = $5,000 / $400 = 12.5 months
Is payback <12 months? (Excellent)
Is payback <18 months? (Acceptable)
Do you have cash runway to sustain payback period?
Critical insight: 4:1 LTV:CAC with 36-month payback is a cash trap. 3:1 LTV:CAC with 8-month payback is better for growth.
Contribution Margin Contribution Margin = (Revenue - All Variable Costs) / Revenue × 100
Variable Costs include:
- COGS
- Support costs (variable component)
- Payment processing
- Variable customer success costs
Revenue: $1,000,000
COGS: $200,000
Variable Support: $50,000
Payment Processing: $30,000
Contribution Margin = ($1M - $280K) / $1M = 72%
Is contribution margin >60%? (Good for SaaS)
Are certain products/segments lower margin? (Consider sunsetting)
Does margin improve with scale?
Step 2: Calculate Capital Efficiency
Burn Rate Gross Burn Rate = Total Monthly Cash Spent
Net Burn Rate = Total Monthly Cash Spent - Monthly Revenue
Monthly Expenses: $800,000
Monthly Revenue: $400,000
Gross Burn: $800,000/month
Net Burn: $400,000/month
Is net burn decreasing over time? (Path to profitability)
Is burn rate sustainable given runway?
What's the burn rate relative to revenue? (Burn multiple)
Runway Runway (months) = Cash Balance / Monthly Net Burn
Cash Balance: $6,000,000
Net Burn: $400,000/month
Runway = $6M / $400K = 15 months
Do you have >12 months runway? (Healthy)
Do you have <6 months runway? (Crisis—raise now or cut burn)
Can you reach next milestone before runway ends?
Rule: Start fundraising at 6-9 months runway, not 3 months.
Operating Expenses (OpEx) OpEx = Sales & Marketing + R&D + General & Administrative
Track as % of Revenue:
S&M as % of Revenue
R&D as % of Revenue
G&A as % of Revenue
Revenue: $10M/year
S&M: $5M (50% of revenue)
R&D: $3M (30% of revenue)
G&A: $1M (10% of revenue)
Total OpEx: $9M (90% of revenue)
Are OpEx categories growing slower than revenue? (Operating leverage)
Is S&M spend efficient? (Check magic number)
Is G&A <15% of revenue? (Should stay low)
Net Income (Profit Margin) Net Income = Revenue - COGS - OpEx
Profit Margin % = Net Income / Revenue × 100
Revenue: $10M
COGS: $2M
OpEx: $9M
Net Income = $10M - $2M - $9M = -$1M (loss)
Profit Margin = -10%
Is profit margin improving over time? (Path to profitability)
At current growth rate, when will you break even?
Are you investing losses in growth? (Acceptable if LTV:CAC is healthy)
Step 3: Calculate Efficiency Ratios
Rule of 40 Rule of 40 = Revenue Growth Rate % + Profit Margin %
Revenue Growth: 80% YoY
Profit Margin: -30%
Rule of 40 = 80% + (-30%) = 50 ✅ Healthy
Revenue Growth: 25% YoY
Profit Margin: 20%
Rule of 40 = 25% + 20% = 45 ✅ Healthy
Revenue Growth: 30% YoY
Profit Margin: -35%
Rule of 40 = 30% + (-35%) = -5 🚨 Unhealthy
Is Rule of 40 >40? (Healthy balance)
Is Rule of 40 >25? (Acceptable)
Is Rule of 40 <25? (Burning cash without sufficient growth)
Early stage: Maximize growth, accept losses (60% growth, -20% margin = 40)
Growth stage: Balance (40% growth, 5% margin = 45)
Mature: Prioritize profitability (20% growth, 25% margin = 45)
Magic Number Magic Number = (Current Quarter Revenue - Previous Quarter Revenue) × 4 / Previous Quarter S&M Spend
Q2 Revenue: $2.5M
Q1 Revenue: $2.0M
Q1 S&M Spend: $800K
Magic Number = ($2.5M - $2.0M) × 4 / $800K = $2M / $800K = 2.5
Is magic number >0.75? (Efficient—scale S&M spend)
Is magic number 0.5-0.75? (Acceptable—optimize before scaling)
Is magic number <0.5? (Inefficient—fix GTM before spending more)
>1.0 = For every $1 in S&M, you get $1+ in new ARR (excellent)0.75-1.0 = Efficient, scale confidently0.5-0.75 = Marginal, optimize before scaling<0.5 = Inefficient, fix before investing more
Operating Leverage Track over time to see if you're scaling efficiently.
Quarter Revenue YoY Growth OpEx YoY Growth Leverage Q1 2024 $8M - $6M - - Q2 2024 $10M 25% $7M 17% Positive ✅ Q3 2024 $12M 20% $9M 29% Negative ⚠️
Is revenue growing faster than OpEx? (Positive leverage)
Are you scaling OpEx too fast relative to revenue?
Which OpEx category is growing fastest? (R&D, S&M, G&A)
Step 4: Analyze by Segment and Channel Unit economics vary dramatically by segment:
Segment CAC LTV LTV:CAC Payback Gross Margin SMB $500 $2,000 4:1 8 months 75% Mid-Market $5,000 $25,000 5:1 12 months 80% Enterprise $50,000 $300,000 6:1 24 months 85%
Which segment has best unit economics?
Which segment has fastest payback? (Prioritize when cash-constrained)
Which segment has highest LTV? (Invest in retention/expansion)
Examples See examples/ folder for detailed scenarios. Mini examples below:
Example 1: Healthy Unit Economics Company: CloudAnalytics (mid-market analytics SaaS)
CAC: $8,000
LTV: $40,000
LTV:CAC: 5:1 ✅
Payback Period: 10 months ✅
Gross Margin: 82% ✅
Monthly Net Burn: $300K
Runway: 18 months ✅
Rule of 40: 55 (40% growth + 15% margin) ✅
Magic Number: 0.9 ✅
Strong unit economics (5:1 LTV:CAC, 10-month payback)
Efficient GTM (0.9 magic number)
Healthy balance (Rule of 40 = 55)
Sufficient runway (18 months)
Action: Scale acquisition aggressively. Economics support growth.
Example 2: Good LTV:CAC, Bad Payback (Cash Trap) Company: EnterpriseCRM (enterprise sales motion)
CAC: $80,000
LTV: $400,000
LTV:CAC: 5:1 ✅ (looks great!)
Payback Period: 36 months 🚨 (terrible!)
Gross Margin: 85%
Monthly Net Burn: $2M
Runway: 9 months 🚨
Average Customer Lifetime: 48 months
Average Contract: $100K/year
⚠️ Great LTV:CAC ratio (5:1) masks cash problem
🚨 36-month payback with 9-month runway = cash trap
🚨 Takes 3 years to recover CAC, but only 9 months of cash
⚠️ Customers stay 4 years, so economics work IF you have cash
Problem: You'll run out of cash before recovering acquisition costs.
Negotiate upfront annual payments (reduce payback to 12 months)
Raise capital to extend runway (need 36+ months to sustain growth)
Reduce CAC (shorten sales cycle, improve conversion)
Target smaller deals with faster payback (mid-market vs. enterprise)
Example 3: Scaling Too Fast (Negative Operating Leverage) Company: SocialScheduler (SMB social media tool)
Quarter-over-Quarter Trend:
Quarter Revenue OpEx Net Income Revenue Growth OpEx Growth Q1 $1.0M $800K -$800K - - Q2 $1.3M $1.2M -$1.2M 30% 50% 🚨 Q3 $1.6M $1.8M -$1.8M 23% 50% 🚨
🚨 OpEx growing FASTER than revenue (50% vs. 23-30%)
🚨 Losses accelerating ($800K → $1.8M in 2 quarters)
🚨 Negative operating leverage (should be positive)
⚠️ Scaling S&M and R&D without corresponding revenue growth
Problem: Burning cash faster while revenue growth is slowing.
Freeze headcount until revenue catches up
Cut inefficient S&M spend (magic number likely <0.5)
Focus on improving unit economics before scaling
Aim for OpEx growth <revenue growth
Common Pitfalls
Pitfall 1: Celebrating High LTV Without Checking Payback Symptom: "Our LTV:CAC is 6:1, amazing!"
Consequence: 6:1 ratio with 48-month payback is a cash trap. You'll run out of money before recovering CAC.
Fix: Always pair LTV:CAC with payback period. 3:1 with 10-month payback beats 6:1 with 36-month payback.
Pitfall 2: Ignoring Gross Margin When Calculating LTV Symptom: "LTV = $100/month × 36 months = $3,600"
Consequence: You're using revenue, not profit. Actual LTV after 30% COGS = $2,520, not $3,600.
Fix: Always include gross margin in LTV calculations. LTV = ARPU × Margin % / Churn Rate.
Pitfall 3: Scaling S&M with Low Magic Number Symptom: "We need to grow faster—let's double S&M spend!" (Magic Number = 0.3)
Consequence: You're pouring gas on a broken engine. Doubling spend will just accelerate cash burn without proportional revenue growth.
Fix: Only scale S&M when magic number >0.75. If <0.5, fix GTM efficiency first.
Pitfall 4: Using Simplistic LTV Formulas Symptom: "LTV = ARPU × Lifetime" (ignoring expansion, discount rates, cohort variance)
Consequence: Overstating LTV for decision-making. Reality: expansion boosts LTV; discounting reduces it; cohorts vary.
Fix: Use sophisticated LTV models for big decisions. Simple LTV ok for directional guidance only.
Pitfall 5: Forgetting Time Value of Money Symptom: "$10K revenue today = $10K revenue in 5 years"
Consequence: Overstating LTV for long-payback businesses. $10K in 5 years is worth ~$7.8K today (at 5% discount rate).
Fix: Discount future cash flows for LTV periods >24 months. Use NPV (net present value).
Pitfall 6: Comparing CAC Across Different Payback Periods Symptom: "Channel A has $5K CAC, Channel B has $8K CAC—Channel A is better!"
Consequence: If Channel A has 24-month payback and Channel B has 8-month payback, Channel B is actually better (faster cash recovery).
Fix: Compare CAC + payback together, not CAC in isolation.
Pitfall 7: Celebrating Rule of 40 >40 with Negative Cash Flow Symptom: "Rule of 40 = 50, we're crushing it!" (60% growth, -10% margin, burning $5M/month)
Consequence: Rule of 40 doesn't account for absolute burn. You might have great balance but only 3 months runway.
Fix: Pair Rule of 40 with burn rate and runway. Balance matters, but survival matters more.
Pitfall 8: Ignoring Segment-Specific Unit Economics Symptom: "Blended CAC is $2K, blended LTV is $10K, we're good!"
Consequence: SMB segment might have $500 CAC / $2K LTV (great), while Enterprise has $20K CAC / $15K LTV (terrible). Blended metrics hide the problem.
Fix: Calculate unit economics by segment. Optimize each independently.
Pitfall 9: Confusing Gross Margin with Contribution Margin Symptom: "Gross margin is 80%, our margins are great!"
Consequence: After variable support costs (10%) and payment processing (3%), contribution margin might be 67%—not 80%.
Fix: Track both gross margin (COGS only) AND contribution margin (all variable costs). Use contribution margin for unit economics.
Pitfall 10: Forgetting Working Capital Timing Symptom: "We have 12 months runway based on burn rate" (but all contracts are paid monthly)
Consequence: Annual contracts paid upfront boost cash temporarily. Monthly contracts delay cash collection. Runway is longer/shorter than burn rate suggests.
Fix: Account for working capital when calculating runway. Cash-based runway ≠ revenue-based runway.
References
Related Skills
saas-revenue-growth-metrics — Revenue, retention, and growth metrics that feed into LTVfinance-metrics-quickref — Fast lookup for all metricsfeature-investment-advisor — Uses margin and contribution calculations for feature ROIacquisition-channel-advisor — Uses CAC, LTV, payback for channel evaluationbusiness-health-diagnostic — Uses efficiency metrics for health checks
External Frameworks
David Skok (Matrix Partners): "SaaS Metrics" blog — Definitive guide to CAC, LTV, paybackBessemer Venture Partners: "SaaS Metrics 2.0" — Rule of 40, magic number benchmarksBen Murray: The SaaS CFO — Advanced unit economics modelingJason Lemkin (SaaStr): SaaS benchmarking researchBrad Feld: Venture Deals — Understanding investor perspective on unit economics
Provenance
Adapted from research/finance/Finance for Product Managers.md
Consolidated from research/finance/Finance_QuickRef.md
Common mistakes from research/finance/Finance_Metrics_Additions_Reference.md
