i'm only sort of joking when i say that your cac charts should go down and to the right whileyour ltv charts should go up and to the right.
some of the a16z team recently posted about 16 metrics -- #5 and #8 (pasted below) will be of particular interest to you.
#5 LTV (Life Time Value)
Lifetime value is the present value of the future net profit from the customer over the duration of the relationship. It helps determine the long-term value of the customer and how much net value you generate per customer after accounting for customer acquisition costs (CAC).
A common mistake is to estimate the LTV as a present value of revenue or even gross margin of the customer instead of calculating it as net profit of the customer over the life of the relationship.
Reminder, here’s a way to calculate LTV:
Revenue per customer (per month) = average order value multiplied by the number of orders.
Contribution margin per customer (per month) = revenue from customer minus variable costs associated with a customer. Variable costs include selling, administrative and any operational costs associated with serving the customer.
Avg. life span of customer (in months) = 1 / by your monthly churn.
LTV = Contribution margin from customer multiplied by the average lifespan of customer.
Note, if you have only few months of data, the conservative way to measure LTV is to look at historical value to date. Rather than predicting average life span and estimating how the retention curves might look, we prefer to measure 12 month and 24 month LTV.
Another important calculation here is LTV as it contributes to margin. This is important because a revenue or gross margin LTV suggests a higher upper limit on what you can spend on customer acquisition. Contribution Margin LTV to CAC ratio is also a good measure to determine CAC payback and manage your advertising and marketing spend accordingly.
See also Bill Gurley on the “dangerous seductions” of the lifetime value formula.
#8 CAC (Customer Acquisition Cost) ... Blended vs. Paid, Organic vs. Inorganic
Customer acquisition cost or CACshould be thefullcost of acquiring users, stated on a per user basis.Unfortunately, CAC metrics come in all shapes and sizes.
One common problem with CAC metrics is failing to include all the costs incurred in user acquisition such as referral fees, credits, or discounts. Another common problem is to calculate CAC as a "blended" cost (including users acquired organically) rather than isolating users acquired through "paid" marketing. Whileblended CAC[total acquisition cost / total new customers acquired across all channels] isn't wrong, it doesn't inform how well your paid campaigns are working and whether they're profitable.
This is why investors considerpaid CAC[total acquisition cost/ new customers acquired through paid marketing] to be more important than blended CAC in evaluating the viability of a business -- it informs whether a company can scale up itsuser acquisition budget profitably. While an argument can be made in some casesthat paid acquisition contributes to organic acquisition, one would need to demonstrate proof of that effect to put weight on blended CAC.
Many investors do like seeing both, however: the blended number as well as the CAC, broken out by paid/unpaid. We also like seeing the breakdown by dollars of paid customer acquisition channels: for example, how much does a paying customer cost if they were acquired via Facebook?
Counterintuitively, it turns out that costs typically goupas you try and reach a larger audience. So it might cost you $1 to acquire your first 1,000 users, $2 to acquire your next 10,000, and $5 to $10 to acquire your next 100,000. That's why you can't afford to ignore the metrics about volume of users acquired via each channel.