The LTV number most operators get wrong
Most LTV calculators on the internet ask you for "average customer lifetime in months" and multiply by ARPU. That input is a guess and inflates the answer by 2-3x. Real customers churn every month, not on calendar-year anniversaries. The correct formula uses monthly churn rate as the denominator, which compounds geometrically and produces the number you can defend to a CFO, a board, or an investor.
Why gross margin matters more than people think
A clinic with £200/month memberships and 75% gross margin generates £150/month in contribution per customer. The other 25% is consumables, treatment time, card fees, and overhead. If you compute LTV on ARPU alone you double the number that actually accrues to the bottom line. For UK SMB service businesses the realistic gross margin range is 60-85%. Pure SaaS sits at 75-90%. Restaurant or beauty product retail can be 30-50%.
The LTV : CAC ratio that matters
The single most useful unit-economic check: divide net LTV by customer acquisition cost. Under 1x and you are paying more to acquire customers than they will ever generate. Between 1x and 3x and you are funding growth out of margin (workable only if you have cash reserves). Above 3x is healthy. Above 5x and you should usually be spending more on acquisition because you are under-investing relative to the return.
The payback period that signals trouble
CAC payback measures the months until a customer has repaid their acquisition cost in gross profit. Healthy SMB SaaS sits at 6-12 months. Anything longer than 18 months and your runway needs to cover the gap. Anything over 24 months and you are essentially a private-equity-backed growth business funding the gap out of investor cash.
Where NuvenarHub fits
Two ways NuvenarHub moves the LTV number. First, the AI WhatsApp agent and automated retention sequences reduce monthly churn (most clinic operators on NuvenarHub see monthly churn drop 1-2 percentage points within 90 days). Second, the ROAS attribution surface means you can spot which ad campaigns produce lower-LTV customers and reallocate spend. Both effects compound over 12-24 months.