Why investors compute gmLTV, not LTV, and what the missing G costs you

There is a version of lifetime value that makes almost any company look fundable, and there is the version an investor actually uses. The difference is a single letter. LTV is built on revenue. gmLTV is built on gross margin. Founders quote the first. The other side of the table quietly recomputes the second before they say a word about your CAC.

The gap between the two is not a rounding error. On a healthy software business it is a quarter of your headline number. On a lot of others it is closer to half.

The dollar that was never a dollar

Lifetime value is meant to answer one question: how much is a customer worth over the time they stay? The common formula takes average revenue per account and divides by the churn rate. A customer paying $1,000 a month who churns at 2% a month has a lifetime of fifty months and a revenue LTV of $50,000.

But you never got to keep $50,000. Serving that customer costs something every month: hosting, support, payment processing, the third-party APIs your product calls, the portion of your infrastructure that scales with usage. If your gross margin is 70%, only $700 of each $1,000 was ever value. The other $300 was always going back out the door.

Revenue LTV counts the whole thousand. That is why it flatters. It treats top line as if it were contribution, and it is not.

What the missing G does to the ratio

Fold gross margin back in and the arithmetic is unforgiving. gmLTV is average revenue times gross margin percent, divided by churn. Take the same customer against a CAC of $10,000.

At the revenue line, LTV over CAC is $50,000 over $10,000, a clean 5.0. Put it on 70% gross margin and gmLTV is $35,000, so the ratio is 3.5. Put it on 60% margin, common for anything with real infrastructure cost or a services component, and it is 3.0. Nothing about the business changed. The number moved because you stopped counting money you never kept.

The scaling is exact: revenue LTV over CAC overstates the real ratio by the inverse of your gross margin. At 80% margin you are inflating by 25%. At 50% you are doubling it. A deck that leads with a 6x built on revenue is describing a 3x business if half of every dollar goes to COGS, and the reader knows how to do that division in their head.

Whose gross margin, exactly

Here is where it stops being arithmetic and becomes diligence. gmLTV is only as honest as the margin you feed it, and gross margin is one of the easier numbers to quietly improve.

The lever is what you put in cost of goods sold. Leave hosting in operating expense instead of COGS and margin climbs. Book customer support as G&A rather than cost of revenue and it climbs again. Keep the cost of a bundled onboarding or a professional-services team out of the line entirely and the software looks purer than it is. Each choice lifts gross margin, and every point of margin flows straight into gmLTV.

So an underwriter does not take your gross margin as given. They ask what is inside COGS, whether it holds the full cost of delivering the product, and whether the margin is stable or drifting as you scale. A gmLTV built on an inflated margin is the same overstatement as revenue LTV, just one layer harder to see.

What this changes at the table

The practical consequence is simple. When you present LTV over CAC, assume it will be rebuilt on gross-margin lifetime value, using a COGS definition that includes everything you might have left out. If your story survives that translation, you walk in with the stronger number already on the page and nothing to defend. If it does not, you want to be the one who found the gap.

The companies that handle this well are not the ones with the highest ratio. They are the ones whose ratio means the same thing on both sides of the table.

Levian rebuilds lifetime value from your transaction file the way an investor would, on gross margin rather than revenue, with a single period-wide margin applied to every cohort so the ratio holds steady across vintages. You see your gmLTV by cohort, and the CAC it sits against, before anyone across the table computes it for you.