What is a good LTV to CAC ratio?

Three to one is the conventional target: three dollars of lifetime gross margin for every dollar of acquisition cost. Below 1:1 you lose money on every customer. Above 5:1 usually signals under-spending on growth rather than excellence. Treat the 3:1 figure as industry convention — no federal or trade body publishes it as a standard.

How do I calculate CAC correctly?

Divide all sales and marketing costs in a period by new customers acquired in that period. All costs means ad spend, sales and marketing salaries and commissions, CRM and automation tooling, agency fees, content production, and events. Omitting salaries is the most common error and typically halves the reported figure in any business with a sales team.

What is the difference between gross margin and contribution margin?

Gross margin removes only direct cost of goods — hosting, materials, direct labor. Contribution margin also removes variable costs tied to serving that specific customer: payment processing, support time, onboarding. On an $80 subscription with $16 of COGS and $12 of service cost, gross margin is 80% but contribution margin is 65%, and the second number is the one that funds overhead.

How long should CAC payback take?

Under twelve months is comfortable for a small business funding growth from operations, and up to 18 months is workable with committed financing. Beyond that, each new customer becomes a cash drain even while looking profitable on a lifetime basis. Payback matters more than the ratio because it determines how much working capital growth consumes.

Business & Tax

Unit Economics Explained: The Metrics That Determine If Your Business Works (2026)

Discover the fundamentals of unit economics explained. Learn how key metrics impact your business's profitability and customer value.

By FreeCalculators Editorial · Published 2026-09-01 · Updated 2026-09-04 · 5 min read · 1103 words

Unit economics is the profit or loss on a single unit of sale — one customer, one subscription, one transaction — measured after every cost that varies with that unit. If the unit loses money, growth multiplies the loss rather than curing it, which is why the question is settled before scaling and not after. Four numbers carry the whole analysis: customer acquisition cost, lifetime value, gross margin, and contribution margin.

The Four Numbers and How to Calculate Each

CAC is total sales and marketing spend for a period divided by new customers acquired in that period — including salaries, ad spend, tooling, content, and events, not just media. LTV is average revenue per customer per period, multiplied by gross margin, multiplied by the expected number of periods retained. Gross margin is revenue less direct cost of delivery. Contribution margin goes one step further and removes every variable cost attributable to the customer: payment processing, support hours, onboarding, hosting.

The four unit-economics inputs and the ratio built from them. Note that LTV is a margin figure, not a revenue figure — using revenue LTV overstates the ratio by the whole cost of delivery.
Metric	Formula	What it excludes
CAC	Sales + marketing spend ÷ new customers	Excludes cost to serve after the sale
Gross margin %	(Revenue − direct COGS) ÷ revenue	Excludes support, processing, overhead
Contribution margin	Revenue − COGS − variable cost to serve	Excludes fixed overhead and salaries
LTV	ARPU × gross margin % × periods retained	Excludes acquisition cost — that is CAC
LTV:CAC	LTV ÷ CAC	Excludes payback timing, which matters separately

Reading the LTV:CAC Ratio

The 3:1 rule — three dollars of lifetime margin for every dollar of acquisition cost — is the most repeated benchmark in the field and also the least sourced. No agency publishes it; it originated as venture-capital shorthand for a business that can fund its own growth, and it is folk wisdom rather than data. It is still useful as a band, provided you know why each band sits where it does.

Practitioner interpretation bands for LTV:CAC. Treat these as convention, not published statistics.
LTV:CAC	What it usually means	The action it implies
Below 1:1	Every new customer destroys value	Stop spending; fix pricing or retention first
1:1 to 2:1	Thin — no margin for a bad quarter	Raise price or cut CAC before adding spend
3:1 to 5:1	Healthy and self-funding	Scale acquisition while watching payback months
Above 5:1	Likely under-investing in growth	Test higher acquisition spend deliberately

Why Payback Period Beats the Ratio

A 4:1 ratio earned over a seven-year customer life is a very different business from a 4:1 ratio earned in nine months, because the first one needs years of financing to bridge the gap. CAC payback — months of contribution margin needed to repay acquisition cost — is the number that determines whether growth consumes cash. The Federal Reserve Small Business Credit Survey, published annually by the twelve Reserve Banks, repeatedly finds paying operating expenses among the most commonly cited financial challenges for small employer firms, which is what a long payback period looks like from the inside.

Worked example: a subscription business (2026)

                Monthly price                            = $80
Direct COGS (hosting, licenses)          = $16  -> gross margin 80%
Variable cost to serve (support, fees)   = $12
Contribution margin per month            = $80 - $16 - $12 = $52
Monthly churn 3%  -> average life = 1 / 0.03 = 33 months
LTV (margin basis) = $52 x 33            = $1,716
Sales + marketing spend, quarter         = $96,000
New customers in quarter                 = 120
CAC = $96,000 / 120                      = $800
LTV:CAC = $1,716 / $800                  = 2.1 : 1
CAC payback = $800 / $52                 = 15.4 months

That business is viable but not yet fundable at scale: a 2.1:1 ratio with a 15-month payback means every 120 new customers tie up $96,000 for well over a year. Cutting churn from 3% to 2% extends average life to 50 months and lifts LTV to $2,600, moving the ratio to 3.3:1 without spending a dollar more on acquisition. Retention is almost always the cheapest lever in the model.

Four Ways Unit Economics Get Misstated

Using revenue LTV instead of margin LTV, which inflates the ratio by the entire cost of delivery — an 80% margin business overstates by 25%.
Excluding sales salaries from CAC and counting only ad spend, which typically understates true CAC by half in any business with a sales team.
Averaging CAC across channels, hiding one channel that is profitable and one that is not.
Estimating customer life from a hopeful churn assumption rather than an observed cohort, which is where most 10:1 ratios come from.

Frequently asked questions

What is a good LTV to CAC ratio?: Three to one is the conventional target: three dollars of lifetime gross margin for every dollar of acquisition cost. Below 1:1 you lose money on every customer. Above 5:1 usually signals under-spending on growth rather than excellence. Treat the 3:1 figure as industry convention — no federal or trade body publishes it as a standard.
How do I calculate CAC correctly?: Divide all sales and marketing costs in a period by new customers acquired in that period. All costs means ad spend, sales and marketing salaries and commissions, CRM and automation tooling, agency fees, content production, and events. Omitting salaries is the most common error and typically halves the reported figure in any business with a sales team.
What is the difference between gross margin and contribution margin?: Gross margin removes only direct cost of goods — hosting, materials, direct labor. Contribution margin also removes variable costs tied to serving that specific customer: payment processing, support time, onboarding. On an $80 subscription with $16 of COGS and $12 of service cost, gross margin is 80% but contribution margin is 65%, and the second number is the one that funds overhead.
How long should CAC payback take?: Under twelve months is comfortable for a small business funding growth from operations, and up to 18 months is workable with committed financing. Beyond that, each new customer becomes a cash drain even while looking profitable on a lifetime basis. Payback matters more than the ratio because it determines how much working capital growth consumes.

Calculators in this guide

CAC to LTV Calculator
Calculate the ratio of customer acquisition cost to lifetime value with our CAC LTV calculator to assess your business profitability.
Revenue Per Employee Calculator
Calculate revenue per employee to evaluate productivity and ensure your team is right-sized for optimal performance and profitability.
Gross Profit Margin Calculator
Calculate your gross profit margin easily. This tool helps you assess pricing power and production efficiency for informed business decisions.
Contribution Margin Calculator
Calculate your contribution margin per unit by entering price and variable costs. Understand how each sale contributes to your fixed costs and profit.