PricingNest

Break-Even CAC Calculator

Estimate the maximum CAC you can afford given ARPA, gross margin, churn, and a target payback period.

Inputs

Scenarios

Applies to the selected input only; adjust other inputs manually if needed.

Results

Break-even CAC (payback target)
-
-
Estimated LTV
-
-
LTV:CAC (using break-even CAC)
-
-

Insights

Auto-generated from your inputs.
Adjust inputs to see recommendations.

Compare

Save a baseline to see deltas for every output.
Break-even CAC (payback target)
Baseline -
Delta -
Estimated LTV
Baseline -
Delta -
LTV:CAC (using break-even CAC)
Baseline -
Delta -

Sensitivity

Adjust the input to see how outputs respond to small changes.
Break-even CAC (payback target)
Low -
Base -
High -
Estimated LTV
Low -
Base -
High -
LTV:CAC (using break-even CAC)
Low -
Base -
High -

Guide

This page is a calculator first, but it's also a quick reference you can share internally. Start with the presets, then adjust inputs and copy the share link. Example defaults for this tool are shown below.

Example Inputs Outputs How it works Modeling tips Validation checks Common mistakes Interpretation Use cases Mini walkthroughs Scenarios Edge cases FAQ

Example (defaults)

Example inputs: ARPA (monthly) = 200, Gross margin (%) = 80, Monthly churn (%) = 3

Break-even CAC (payback target)
$1,440.00
Estimated LTV
$5,333.33
LTV:CAC (using break-even CAC)
3.703704

Inputs explained

Input Default Notes
Currency USD Adjust to match your product assumptions.
ARPA (monthly) 200 Adjust to match your product assumptions.
Gross margin (%) 80 Adjust to match your product assumptions.
Monthly churn (%) 3 Adjust to match your product assumptions.
Target payback (months) 9 Adjust to match your product assumptions.

Outputs explained

Output What it means
Break-even CAC (payback target) A money value based on your selected currency.
Estimated LTV A money value based on your selected currency.
LTV:CAC (using break-even CAC) A numeric value derived from the inputs.

How it works

  • Gross profit per month = ARPA x gross margin.
  • Break-even CAC (payback) = gross profit per month x target payback months.
  • We also compute a simple churn-based LTV for context.

Modeling tips

  • Use a target payback window that matches your cash flow constraints.
  • ARPA should be monthly recurring revenue after discounts.
  • Use contribution margin if fulfillment costs are significant.
  • Use a realistic monthly churn rate for the segment you are acquiring.
  • Compare break-even CAC to actual CAC to see if acquisition is sustainable.
  • Use net churn only if expansion is predictable and stable.

Validation checks

  • Break-even CAC should equal gross profit per month x target payback months.
  • LTV should equal gross profit per month x implied lifetime.
  • LTV:CAC should be greater than 1 for a healthy model.
  • Break-even CAC should not exceed LTV for long-term viability.

Common mistakes

  • Confusing break-even CAC with maximum CAC based on full LTV.
  • Using gross churn when net churn is more appropriate for the segment.
  • Setting a payback window that does not match cash flow reality.
  • Assuming ARPA is steady despite usage ramp or seasonality.

Interpretation

  • Use break-even CAC as a hard ceiling for paid acquisition.
  • If break-even CAC is below actual CAC, fix retention or pricing first.
  • Use the LTV:CAC ratio to compare segments consistently.
  • Shorten payback targets when cash is tight.

Use cases

Spend limits
Set maximum CAC targets for each segment before scaling spend.
Pricing justification
Validate whether a price increase raises your CAC ceiling.

Mini walkthroughs

Break-even CAC
  1. Enter ARPA, gross margin, churn, and payback target.
  2. Review break-even CAC and LTV outputs.
  3. Use the result as a CAC ceiling.
Tighten payback
  1. Shorten the payback target by a few months.
  2. Compare the reduced CAC ceiling.
  3. Adjust acquisition spend accordingly.

Scenarios

SMB acquisition
ARPA 120 with 4% churn and 8-month payback to find a safe CAC ceiling.
Mid-market acquisition
Higher ARPA with lower churn to see how CAC capacity expands.
Ramp-up impact
Increase payback months to reflect longer onboarding or adoption.
High churn segment
Higher churn to show how CAC capacity shrinks when retention is weak.

Edge cases

  • If target payback is 0, break-even CAC will be 0; set a realistic window.
  • If churn is 0, LTV becomes unbounded; use a churn floor.
  • If gross margin is low, break-even CAC will be low.
  • If churn is high, LTV can fall below break-even CAC quickly.

FAQ

Why show LTV:CAC?
It is a common SaaS sanity-check metric. This tool estimates it using break-even CAC and simple LTV.
What does break-even CAC mean here?
It's the CAC you can afford to recover within your target payback window based on gross profit per month.
How should I pick target payback months?
Shorter payback is safer for cash flow. Many teams choose 6-12 months depending on sales cycle length, expansion, and capital constraints.
Should I use segment-specific CAC?
Yes. CAC varies widely by channel and segment, so break-even CAC should be calculated per segment.
How do I use this with LTV targets?
Compare break-even CAC to your actual CAC and ensure LTV:CAC exceeds your internal target (often 3x).
What if LTV:CAC is below 1?
It means your acquisition is not paying back within a reasonable lifetime. Revisit pricing, retention, or CAC efficiency.