SaaS LTV:CAC Calculator

The two numbers most cited in SaaS fundraising and planning: the LTV:CAC ratio and the CAC payback period. This calculator derives both from the underlying drivers so you can see which lever moves them.

Inputs

ARPU / month

Gross margin

Monthly churn

CAC

Results

LTV:CAC ratio

4.57×

CAC payback: 8.8 months
Margin-adjusted LTV: $2,970.00

Ratio ≥ 3 with payback under 12 months is the classic healthy zone. Payback matters most when cash is constrained; ratio matters most for long-run efficiency.

Formula

LTV:CAC = (ARPU × Margin ÷ Churn) ÷ CAC · Payback = CAC ÷ (ARPU × Margin)

FAQ

Which lever is easiest to improve?

Usually churn — it raises LTV without any extra spend. CAC improvements depend on channel headroom; pricing raises both ARPU and often LTV at once.

Do these metrics work for annual plans?

Convert to monthly equivalents first (annual contract value ÷ 12). Consistency of units is what keeps the ratio meaningful.