Customer Revenue
Average revenue per user per month.
2026 SaaS median: 70-80%.
Lifespan = 1 / Monthly Churn Rate. 3.3% monthly churn = 30 months.
Customer Acquisition Cost
Monthly or quarterly total spend.
In same period as spend above.
Your Results
Enter revenue and acquisition data to calculate.
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Introduction
The LTV:CAC ratio is the closest thing to a universal health metric in subscription software. It answers the fundamental question every SaaS business must resolve: does acquiring a customer generate more value than it costs? According to David Skok's SaaS Metrics framework, widely accepted as the SaaS industry standard, a healthy business maintains an LTV:CAC ratio above 3:1. Below 3:1, you are paying too much to acquire customers relative to the revenue they generate. Above 5:1, you are likely underinvesting in growth. The ratio sounds simple. The calculation is not. LTV requires an accurate churn rate, not a guess. CAC must include all sales and marketing costs, not just paid advertising. Most SaaS companies that calculate LTV:CAC incorrectly are running on a false sense of unit economics security until they run out of cash.
What This Calculator Does
This calculator computes Customer Lifetime Value (LTV), Customer Acquisition Cost (CAC), the LTV:CAC ratio, and CAC payback period in months. Inputs include ARPU, gross margin percentage, monthly churn rate, and total sales and marketing spend with associated new customer count. The tool outputs LTV, blended CAC, LTV:CAC ratio, CAC payback period, and flags whether the ratio is below the 3:1 minimum, in the healthy 3:1 to 5:1 range, or above 5:1 indicating possible underinvestment. It uses 2026 benchmarks from OpenView Partners and Bessemer Venture Partners.
The Formula
LTV uses the gross-margin-adjusted formula because raw revenue LTV overstates the economics by ignoring the cost of delivering the product. A $100/month subscriber with 70% gross margin delivers $70/month of true economic value, so LTV = $70 / monthly churn rate. At 3% monthly churn, LTV = $2,333. CAC is calculated by dividing all sales and marketing costs in a period (salaries, advertising, tools, events) by the number of new customers acquired in that same period. CAC payback measures how many months of gross margin contribution are needed to recover the acquisition cost, which is a cash flow indicator rather than a return indicator.
Step-by-Step Example
Calculate LTV from ARPU, gross margin, and churn
ARPU: $89/month. Gross margin: 74%. Monthly churn rate: 3.2%. LTV = ($89 × 0.74) / 0.032 = $65.86 / 0.032 = $2,058. This means each acquired customer is expected to generate $2,058 in gross profit over their subscription lifetime.
Calculate blended CAC from all sales and marketing costs
Monthly sales and marketing spend: $42,000. This includes: paid ads $18,000, content and SEO $6,000, sales team fully-loaded cost $14,000, tools and software $1,500, events and conferences $2,500. New customers acquired this month: 38. CAC = $42,000 / 38 = $1,105.
Compute LTV:CAC ratio and assess health
LTV:CAC = $2,058 / $1,105 = 1.86:1. This is below the 3:1 minimum threshold. The business is spending more than one-third of a customer's lifetime gross profit just to acquire them. The problem is either CAC too high, churn too high, ARPU too low, or a combination of all three.
Calculate CAC payback period
CAC payback = $1,105 / ($89 × 0.74) = $1,105 / $65.86 = 16.8 months. This means it takes nearly 17 months to recover acquisition costs through gross margin contributions. Healthy SaaS targets 12 months or less. Reducing churn from 3.2% to 2.0% raises LTV to $3,293, bringing the ratio to 2.98:1 and payback to 16.8 months (unchanged, since payback is not affected by churn).
Real-World Use Cases
Pre-Funding Unit Economics Validation
A SaaS founder preparing a Series Seed pitch models LTV:CAC before meeting investors. Current numbers: $59 ARPU, 78% gross margin, 4.5% monthly churn, $22,000/month in marketing. LTV = ($59 × 0.78) / 0.045 = $1,022. If the founder acquires 12 customers per month, CAC = $1,833. Ratio: 0.56:1. This is economically unviable. The calculator reveals the fundraise should focus on product retention improvements before scaling acquisition, not the other way around.
Comparing Paid vs. Organic Acquisition Channel LTV:CAC
A SaaS company runs separate LTV:CAC calculations for paid search (CAC $890) and content-driven organic acquisition (CAC $210, attributed by last-touch attribution). At LTV $2,400, paid channel ratio: 2.7:1. Organic channel ratio: 11.4:1. The organic channel has 4x better unit economics. The strategic implication: shift budget from paid to content investment until organic CAC begins rising due to diminishing returns.
Post-Price-Increase Impact Assessment
After raising base plan price from $49 to $69 (41% increase), a SaaS company models the LTV:CAC impact. Assume 8% voluntary churn from the increase. Pre-increase: LTV = ($49 × 0.75) / 0.035 = $1,050. Post-increase with 8% churners gone: ARPU for retained subscribers = $69. Churn may initially spike to 5% as price-sensitive customers leave. New LTV = ($69 × 0.75) / 0.05 = $1,035. Short-term LTV actually drops slightly as churn spikes, but stabilizes higher as 6-month churn reverts to 3%: new LTV = ($69 × 0.75) / 0.035 = $1,479. The 40.9% long-term LTV improvement makes the price increase worthwhile.
Comparison
| LTV:CAC Ratio | Assessment | Typical Cause | Action Required |
|---|---|---|---|
| Below 1:1 | Catastrophic | Very high CAC or extreme churn | Stop scaling acquisition immediately |
| 1:1 to 2:1 | Unsustainable | Misaligned CAC and LTV | Fix churn or reduce CAC before scaling |
| 2:1 to 3:1 | Marginal | Approaching viability | Optimize both levers in parallel |
| 3:1 to 5:1 | Healthy | Strong unit economics | Scale acquisition with confidence |
| 5:1 to 8:1 | Very good | Efficient acquisition | Consider increasing growth spend |
| Above 8:1 | Potentially underinvesting | Under-spending on acquisition | Test higher acquisition spend |
Common Mistakes to Avoid
Excluding non-advertising sales costs from CAC. CAC is not just paid ad spend. It includes fully-loaded salaries for sales development reps, account executives, and demand generation team members; marketing tools and CRM software; event costs; and content production. Excluding personnel costs can understate true CAC by 3x to 5x for sales-led SaaS companies.
Using raw revenue LTV instead of gross-margin-adjusted LTV. A $100/month subscriber on a product with 60% gross margin delivers $60/month in economic value, not $100. Using unadjusted LTV inflates the ratio by a factor equal to one divided by gross margin. For a 60% margin business, this is a 66% LTV overstatement.
Comparing cohort LTV to blended CAC. If your current acquisition channels have different CAC than historical averages (e.g., CAC has risen 40% due to increased competition in paid search), using blended historical CAC produces an LTV:CAC ratio that looks better than the current reality. Always calculate CAC on the most recent 3 to 6 months of data.
Ignoring CAC payback period as a cash efficiency metric. A 3:1 LTV:CAC ratio with a 36-month payback period means you fund customer acquisition for 3 years before breaking even on each customer. For a company without access to cheap growth capital, this is a cash flow problem even if the long-term economics look good.
Frequently Asked Questions
Accuracy and Disclaimer
LTV and CAC calculations in this tool follow definitions established by David Skok (forentrepreneurs.com), Bessemer Venture Partners, and OpenView Partners' SaaS benchmarks. Results are estimates based on your inputs and are sensitive to assumptions about gross margin, churn rate, and attribution methodology. These calculations are for internal planning and business modeling purposes only and do not constitute investment advice or audited financial reporting.
Conclusion
The LTV:CAC ratio is not a one-time calculation. It needs to be tracked monthly, because both variables move. Churn improvements raise LTV. Rising paid acquisition costs raise CAC. Product price increases raise both ARPU and LTV. Once you know your current ratio, use the Churn Rate Calculator to model what a 1% churn reduction does to LTV, and the ARR Growth Calculator to see how your current LTV:CAC ratio translates to sustainable annual growth rates and runway efficiency.
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