Ratio = CLTV ÷ lifetime retention cost
Where acquisition has CLTV to CAC, retention has this. It asks how much customer value each dollar of retention spend is protecting.
Both terms over the same life
The common error is dividing lifetime value by one period of retention cost, which mixes a multi-year numerator with an annual denominator and produces a number several times too flattering.
Use lifetime retention cost: annual CRC multiplied by the same capped horizon used in the CLTV. If CLTV is capped at five years, so is the cost.
The trend is the signal
The level is hard to benchmark because retention cost definitions vary so much between companies. The direction is not.
A falling ratio with stable churn is the important pattern: you are holding retention, and holding it costs more every quarter. Retention metrics will look fine throughout, because they are.
The usual cause is upstream. Accounts acquired outside the ICP need more help to stay, so acquisition volume is paid for twice, once at CAC and again forever at CRC. That is the same finding described in CLTV to CLP, approached from the cost side.
A worked example
Capped five-year CLTV of $29,900. Annual CRC of $1,875, so $9,375 over the same five years.
Ratio = 29,900 ÷ 9,375 = 3.2
A year later, same CLTV, CRC risen to $2,400 a year:
Ratio = 29,900 ÷ 12,000 = 2.5
Churn did not move. Price did not move. Holding the same customers now returns 22% less per dollar spent, and nothing in a standard retention dashboard would have said so.
The traps
- Annual retention cost against lifetime value.
- Different horizons in the two terms.
- Benchmarking the level rather than watching the trend.
- Attributing shared customer success cost without a stated rule.
Where this sits
Measurement in the Tenbound Pipeline Architecture Standard, and among the earliest financial warnings of a Market problem available. It moves before churn does.