CAC/LTV debates are rarely about the math. They’re about trust.
When CAC/LTV becomes a weekly argument, it usually means:
- different teams use different definitions
- attribution assumptions aren’t stable
- blended averages hide weak channels
- the metric exists without a decision attached
The goal: decision-grade, not perfect
A model can be sophisticated and still useless.
Decision-grade metrics are simpler, stable, and actionable.
Save this: Decision-Grade Unit Economics Standard (v1)
1) One CAC definition (what’s in/out)
2) Payback by channel (not blended)
3) Trend (8–12 weeks)
4) One decision per metric (what this drives)
5) Cadence (weekly/biweekly)
6) Exceptions list (what moved, why)
Why payback is the founder metric
Payback forces the right conversation:
Are we buying growth—or burning runway?
Payback is harder to “storytell” and easier to act on.
Common failure modes (Seed–Series B)
- Blended CAC hides channel decay
- LTV uses assumptions no one can defend
- Discounting shifts payback but isn’t tracked consistently
- Sales cycle length changes but the model doesn’t
- Expansion and churn are discussed qualitatively, not measured consistently
Founder diagnostic
If payback worsens 20% next month, will you notice **early**—or after the quarter ends?
If late, cadence is your first fix.
What to do next (lightweight)
Create a weekly unit economics snapshot:
- CAC (one definition)
- payback by channel
- trendline
- “what changed” notes
- one decision
Fit-check
If you’re VC-backed Seed–Series B and finance feels heavy, reply with:
stage + (cash / close / reporting)
I’ll respond fit/no-fit and what to stabilize first.
Or book:
