SaaS Metrics That Matter

The SaaS Metrics You Must Track

SaaS businesses live and die by a set of well-defined metrics. Investors speak this language. Your team should too. These metrics are not just reporting tools — they are diagnostic instruments that tell you what to fix.

MRR: Monthly Recurring Revenue

MRR is the heartbeat of SaaS. It is the total predictable revenue your business generates each month from subscriptions.

// MRR components
const mrr = {
  new: 2500,        // Revenue from customers who signed up this month
  expansion: 800,   // Revenue from upgrades and plan changes
  contraction: -300, // Revenue lost to downgrades
  churned: -400,    // Revenue lost to cancellations
  netNew: 2500 + 800 - 300 - 400, // = $2,600 net MRR added this month
};

const currentMRR = previousMRR + mrr.netNew;

ARR (Annual Recurring Revenue) = MRR × 12. Used for annual planning and investor conversations.

Churn Rate

Churn is the percentage of revenue (or customers) lost in a period.

// Logo churn (customer count)
const logoChurnRate = customersLost / startingCustomers;
// 5 customers left out of 100 = 5% monthly logo churn

// Revenue churn (dollar amount)
const revenueChurnRate = mrrLost / startingMRR;
// $500 MRR lost from $10,000 = 5% monthly revenue churn

Good churn benchmarks:

• Consumer SaaS: < 5% monthly
• SMB SaaS: < 3% monthly
• Enterprise SaaS: < 1% monthly

Net Revenue Retention (NRR)

NRR measures revenue from existing customers including expansions, contractions, and churn. NRR > 100% means existing customers are growing revenue faster than they churn.

function calculateNRR(
  startingMRR: number,
  expansionMRR: number,
  contractionMRR: number,
  churnedMRR: number
): number {
  return (startingMRR + expansionMRR - contractionMRR - churnedMRR) / startingMRR;
}
// NRR = (10000 + 1500 - 300 - 500) / 10000 = 107%

NRR benchmarks: > 100% = good, > 110% = great, > 120% = exceptional.

CAC: Customer Acquisition Cost

CAC is how much it costs to acquire one paying customer.

const cac = (salesExpense + marketingExpense) / newCustomersAcquired;
// ($15,000 sales + $10,000 marketing) / 50 new customers = $500 CAC

LTV: Lifetime Value

LTV is the total revenue you expect from the average customer over their lifetime.

const ltv = arpu / monthlyChurnRate;
// $49 ARPU / 0.04 churn rate = $1,225 LTV

LTV:CAC Ratio

The ratio of lifetime value to acquisition cost. The most important unit economics metric.

const ltvCacRatio = ltv / cac; // $1,225 / $500 = 2.45:1 — needs improvement

CAC Payback Period

How many months until you recoup the cost of acquiring a customer.

const cacPaybackMonths = cac / arpu; // $500 / $49 = 10.2 months

Under 12 months is good. Under 6 months is excellent.

ARPU: Average Revenue Per User

const arpu = mrr / totalCustomers; // $49,000 / 1,000 = $49 ARPU

Tracking ARPU over time reveals whether you're moving upmarket (good) or downmarket (risky).

The Rule of 40

A heuristic for SaaS business health: your growth rate + profit margin should equal or exceed 40%.

const ruleOf40 = annualGrowthRate + profitMargin;
// 30% growth + 15% margin = 45 — healthy
// 50% growth + (-10%) margin = 40 — aggressive growth stage, acceptable
// 10% growth + (-20%) margin = -10 — problematic

Key Takeaways

• MRR is the heartbeat of SaaS — track new, expansion, contraction, and churned MRR separately
• NRR > 100% means existing customers are growing revenue — this is the hallmark of a healthy SaaS business
• LTV:CAC ratio should be 3:1 or better — below 1:1 means you're destroying value with every new customer
• CAC payback under 12 months provides financial sustainability — you're not funding growth indefinitely before recouping costs
• The Rule of 40: growth rate + profit margin ≥ 40% is the benchmark for a healthy SaaS company