What are SaaS unit economics?

SaaS unit economics measure the profitability of each customer. The key metrics are Customer Acquisition Cost (CAC), Lifetime Value (LTV), LTV:CAC ratio, and payback period. Healthy SaaS businesses target an LTV:CAC ratio of 3:1 or higher.

How do you calculate CAC?

Customer Acquisition Cost (CAC) is calculated by dividing total sales and marketing spend by the number of new customers acquired in that period. For example, $100K spend ÷ 50 new customers = $2,000 CAC.

What is a good LTV:CAC ratio?

A healthy LTV:CAC ratio is 3:1 or higher, meaning each customer generates 3x more value than it costs to acquire them. Below 1:1 means you lose money on every customer. Above 5:1 may indicate underinvestment in growth.

How do you calculate customer LTV for a SaaS startup?

The basic SaaS LTV formula is: Average Revenue Per Account (ARPA) × Gross Margin ÷ Churn Rate. For a $200/mo plan with 80% gross margin and 2% monthly churn: ($200 × 0.80) ÷ 0.02 = $8,000 LTV. Always use gross margin, not revenue alone, because gross profit is what funds acquisition and expansion.

What is CAC payback period?

CAC payback period is how many months of gross margin a customer must generate to repay their acquisition cost. Calculated as CAC ÷ (ARPA × Gross Margin). Top SaaS companies target under 12 months; under 24 is acceptable; over 36 is risky unless you have very low churn.

How are unit economics different for product-led growth (PLG) vs sales-led startups?

PLG businesses typically have lower CAC (self-serve signup) but lower initial ACV; sales-led businesses have higher CAC but larger initial deals and faster expansion. Compare them on LTV:CAC ratio and payback period; both should clear 3:1 and a 12-month payback respectively, regardless of motion.

Should I include free-trial users in CAC calculations?

Only count converted, paying customers in the denominator. Free trials, freemium accounts, and waitlist signups inflate the customer count and understate true CAC. For a more conservative view, calculate paid CAC using only sales and marketing spend that targeted paid acquisition (excluding brand and PR).

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Unit Economics Calculator

Know your CAC, LTV, and payback period: the metrics that determine if your SaaS business scales.

Unit Economics Calculator

Adjust inputs to analyze your customer acquisition economics

S&M Spend ($/mo)New Customers / MoARPU ($/mo)

Monthly Churn (%)Gross Margin (%)

CAC vs LTV

Customer acquisition cost compared to lifetime value

LTV:CAC Ratio

Target is 3x or higher for sustainable growth

10.0x

LTV:CAC Ratio

<1x Critical1-3x Caution>3x Healthy

Healthy

Payback Period

Months to recoup customer acquisition cost

3.3 months

0 mo12 mo18 mo24 mo

<12mo Good12-18mo Fair>18mo Poor

Unit Economics Summary

Key metrics at a glance

CAC (Cost to Acquire)
$500
LTV (Lifetime Value)
$5,000
LTV:CAC Ratio
10.0x
Payback Period
3.3 months
Monthly ARPU
$200

CAC

$500

LTV

$5,000

LTV:CAC

10.0x

Payback

3.3 mo

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Frequently Asked Questions

What are SaaS unit economics?: SaaS unit economics measure the profitability of each customer. The key metrics are Customer Acquisition Cost (CAC), Lifetime Value (LTV), LTV:CAC ratio, and payback period. Healthy SaaS businesses target an LTV:CAC ratio of 3:1 or higher.
How do you calculate CAC?: Customer Acquisition Cost (CAC) is calculated by dividing total sales and marketing spend by the number of new customers acquired in that period. For example, $100K spend ÷ 50 new customers = $2,000 CAC.
What is a good LTV:CAC ratio?: A healthy LTV:CAC ratio is 3:1 or higher, meaning each customer generates 3x more value than it costs to acquire them. Below 1:1 means you lose money on every customer. Above 5:1 may indicate underinvestment in growth.
How do you calculate customer LTV for a SaaS startup?: The basic SaaS LTV formula is: Average Revenue Per Account (ARPA) × Gross Margin ÷ Churn Rate. For a $200/mo plan with 80% gross margin and 2% monthly churn: ($200 × 0.80) ÷ 0.02 = $8,000 LTV. Always use gross margin, not revenue alone, because gross profit is what funds acquisition and expansion.
What is CAC payback period?: CAC payback period is how many months of gross margin a customer must generate to repay their acquisition cost. Calculated as CAC ÷ (ARPA × Gross Margin). Top SaaS companies target under 12 months; under 24 is acceptable; over 36 is risky unless you have very low churn.
How are unit economics different for product-led growth (PLG) vs sales-led startups?: PLG businesses typically have lower CAC (self-serve signup) but lower initial ACV; sales-led businesses have higher CAC but larger initial deals and faster expansion. Compare them on LTV:CAC ratio and payback period; both should clear 3:1 and a 12-month payback respectively, regardless of motion.
Should I include free-trial users in CAC calculations?: Only count converted, paying customers in the denominator. Free trials, freemium accounts, and waitlist signups inflate the customer count and understate true CAC. For a more conservative view, calculate paid CAC using only sales and marketing spend that targeted paid acquisition (excluding brand and PR).

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