Guide

The SaaS metrics that actually predict growth

Not all metrics are equal. Focus on what moves the needle.

By Surfil Updated October 7, 2026

7 min readBack to guides

Key takeaways

If you read nothing else

Seven numbers matter.
Churn is the one founders ignore until it is too late.
An LTV to CAC ratio above 3 is the health line.
A payback under 12 months is one you can live with.

SaaS is a metrics game. You buy customers (CAC), keep them (churn), and grow them (MRR). This covers the 7 numbers every founder tracks, and what each one is telling you.

7: Metrics worth tracking
1: That predicts the rest
<12 mo: Payback you can live with
0: Vanity numbers here

MRR, monthly recurring revenue

MRR = revenue from subscriptions expected to renew next month.

Example: you have 100 customers at $99/month. MRR = $9,900. (Ignore one-time fees; ignore annual plans converted to monthly.)

Why it matters: MRR is the heartbeat. It tells you whether your business is growing, shrinking, or flat. A growth-stage SaaS targets 10% MRR growth monthly (100% annually).

Watch: MRR growth rate (monthly). If it's negative, you're losing customers faster than you acquire them.

Churn rate

Churn = the percentage of customers who cancel each month. If you have 100 customers and 5 cancel, churn is 5%.

Why it matters: churn is the metric founders ignore until it's too late. If churn is 10% monthly, you lose your entire customer base every 10 months. You're running a leaky bucket.

Target churn: < 2% monthly for early-stage SaaS. < 1% for mature SaaS. If you're above 5%, something is broken.

How to improve churn: onboarding (get users to the aha moment faster). Win-back campaigns. Pricing fit. Product roadmap (listen to churn feedback).

Customer acquisition cost (CAC)

CAC = how much you spend to acquire a customer. If you spend $10,000 on marketing and acquire 100 customers, CAC = $100.

Why it matters: if you spend $100 per customer but only make $99 in revenue, you're losing money. CAC determines your go-to-market strategy (word of mouth vs. paid ads).

The calculation: total marketing spend (ads, salaries, tools) / customers acquired = CAC.

Target CAC: it should be < 1/3 of LTV. If LTV is $5,000, CAC should be < $1,500.

Customer lifetime value (LTV)

LTV = total revenue from a customer over their lifetime. If a customer pays $99/month and stays 24 months, LTV = $2,376.

The formula: (ARPU × lifetime) - CAC = true LTV. ARPU = average revenue per user. Lifetime = 1 / monthly churn.

Example: ARPU = $99, monthly churn = 2%, CAC = $500. Lifetime = 1 / 0.02 = 50 months. LTV = (99 × 50) - 500 = $4,450.

Why it matters: the LTV/CAC ratio should be > 3.

Payback period

How many months until a customer's revenue covers their acquisition cost?

The formula: CAC / (ARPU × (1 - churn rate)) = payback period.

Example: CAC = $500, ARPU = $99, monthly churn = 2%. Payback period = 500 / (99 × 0.98) = 500 / 97 = 5.2 months.

Meaning: after 5 months, this customer has paid back their acquisition cost. Everything after month five is profit.

Target payback period: < 12 months (ideally < 6 months). If it's over 24 months, you're running a cash nightmare.

The magic number

The magic number = how much revenue you earn for every dollar of marketing spend.

The formula: (this month's MRR - last month's MRR) / last month's marketing spend = the magic number.

Example: MRR grew from $10,000 to $12,000. Marketing spend = $2,000. Magic number = 2,000 / 2,000 = 1.0.

Meaning: for every dollar you spent, you earned a dollar in new MRR.

Target magic number: > 0.75. If it's > 1.0, double your spend and scale.

Net revenue retention (NRR)

NRR = revenue from existing customers, accounting for churn and expansion (upgrades and add-ons).

Example: you started with $10,000 MRR. This month, $500 churned. But $1,500 expanded. Net change = +$1,000. NRR = 110%.

Why it matters: NRR > 100% means you earn more from existing customers than you lose. You're expanding faster than you churn. That's the sign of a healthy SaaS.

How to improve NRR: reduce churn. Increase expansion revenue (upgrades, add-ons, premium tiers).

Before you move on

The checklist

Tick these off on your own site. Each one comes from the guide.

Track MRR growth every month
Track churn every month
Count every cost in CAC
Know your LTV to CAC ratio
Know your payback in months

In Growth Score

Which pillar it moves

Fixing what this guide describes shows up in this part of your score.

Data & MeasurementHow well you can see what is working.

Glossary

Terms in this guide

MRRMonthly recurring revenue: the predictable subscription revenue a business earns each month.Churn rateThe share of customers or revenue lost in a period because people cancel or stop buying.Customer lifetime valueThe total gross profit you expect from a customer over the time they stay.Customer acquisition costThe total sales and marketing spend needed to win one new customer.

FAQ

Questions after reading

What churn is healthy?

The guide targets under 2 percent a month for early-stage SaaS and under 1 percent when mature. Above 5 percent, something is broken.

Which metric do I track first?

Churn. The guide calls it the number founders ignore until it is too late.

Track the seven, act on the one that is bleeding, and ignore everything a dashboard adds for free.

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