The owner of a small skin care label showed me a single sticky note taped to her laptop: “Is this working?” Last month she spent on ads, sponsored a podcast, sent samples to a few creators and saw a bump in orders. But the bump was messy. Some buyers were returning customers. Some were friends-of-friends. The question behind the note was simple: what did it cost to get a new customer, and what was each customer worth over time?
You do not need a data team to answer that. You need a consistent way to count money out, customers in and the margin you keep. The methods below are intentionally plain. They trade precision for speed and repeatability, which is what you need to make decisions.
The cleanest path to CAC
Customer acquisition cost is the average marketing and sales spend required to win one new customer over a defined period.
Fast version
Use this when you need a number today.
CAC = total acquisition spend in period / number of new customers in same period
What to include in spend: paid ads, creator fees, referral payouts, agency fees, sponsorships and any discounts that are clearly acquisition incentives. Keep the window tight, like a single month or quarter, and be consistent.
What to count as new customers: first ever purchasers in that window. If your platform shows “first-time customers,” use that. For a service business, count first signed clients.
Grounded version
Improve the fast version without making it complicated.
- Make two CACs. Media-only CAC (just ad and promo spend) and fully loaded CAC (media plus salaries for acquisition roles, software used for acquisition, creative production). The first tells you channel efficiency. The second tells you true cost to scale.
- Match timing. Use the same date window for spend and new customers. If your ads take a week to convert, use a rolling window or accept the lag and keep it consistent each month.
- Exclude retention and admin. Email to existing customers, support, printing, general overhead and rent sit outside acquisition.
- Net out taxes and refunds. Track spend and sales net of GST and account for returns so you are not flattering the numbers.
LTV without a complex model
Lifetime value is the gross profit you expect from a typical customer over the life of their relationship with you. The key is to stay on profit, not revenue.
Fast version
If your business sells repeat purchases but you do not have granular data yet:
LTV = average order value x gross margin % x orders per customer per year x average customer lifespan (years)
Estimate orders per year and lifespan from your own history. If you are too new for that, use conservative assumptions, then tighten them each month.
For a subscription, keep it even simpler:
LTV = average monthly gross profit per active customer x average tenure in months
Build it from your sales history
When you have a few months of orders, build LTV from actual behaviour.
- Average order value (AOV). Take total revenue from customers’ first 12 months, divided by number of orders. Exclude GST and shipping charged to customers.
- Gross margin. Revenue minus cost of goods sold, as a percentage. Include packaging and fulfilment costs you pay.
- Order frequency. For customers acquired in a given month, count how many orders they placed over the next 12 months, on average.
- Retention horizon. If most customers fade after about 18 months, use 1.5 years. If you do not know, start with one year and expand as you collect more months of data.
Combine them using the same formula. The important part is consistency. If you measure over 12 months, compare CAC taken in the month of acquisition to LTV expected over that 12-month horizon.
Make the two numbers talk
CAC tells you the cost to win a customer. LTV tells you the profit that customer is likely to generate. The gap between them is the room you have to operate. You want LTV comfortably higher than CAC so you can pay the bills, invest in growth and handle the surprises that always show up.
Two quick checks:
- Payback period. How many months of gross profit does it take to earn back CAC? Faster payback lowers cash strain. If it takes a year to recover, make sure you can fund the gap.
- Channel comparison. Calculate CAC by channel. If search ads deliver a lower CAC than social, shift budget and recheck next month.
Common traps to avoid
- Counting returning customers as new. Use first purchase date to define new customers. Everyone else belongs in retention analysis, not acquisition.
- Forgetting discounts. If you offer 20 percent off to first buyers, that discount reduces gross profit on the first order. Capture it in LTV, not CAC.
- Attribution stretch. Do not claim every sale touched by an ad as acquired by that ad. Keep your window honest and compare like with like each month.
- Margin blindness. Revenue growth is nice. Only margin pays CAC back. Always multiply by gross margin before calling something value.
A short worked example
Imagine a Pilates studio runs a month-long push: digital ads, local flyers and a new-student offer.
- Acquisition spend: ads 6,000, flyers 800, intro offer gift cards 1,200. Total 8,000.
- New customers signed in the month: 200.
Media-only CAC might be 6,800 divided by 200 equals 34. Fully loaded CAC adds staff hours and design help, say another 1,200, so 8,000 divided by 200 equals 40.
Now LTV. The studio’s new-student cohort over the next year shows:
- Average class pack sale after trial: 90.
- Gross margin after instructor pay and rent allocation: 60 percent.
- Average orders in first year: 3.
- Beyond 12 months, most switch to casual visits. The studio uses a 1.5-year horizon for new students.
LTV equals 90 x 0.6 x 3 x 1.5. That is 243 in gross profit over 18 months. With a fully loaded CAC of 40, there is room for overhead, cash timing and some error. Payback period is roughly the first two orders.
Keep it simple, keep it consistent and keep it current. Accuracy comes from repetition, not complexity.
Keep it current
Update CAC and LTV monthly. Use the same spreadsheet, the same inputs and the same definitions. Add one modest improvement at a time. You might start by splitting CAC by channel. Next month, tighten LTV by using actual repeat rates for cohorts acquired three months ago. The month after, add refunds and returns. Small steps maintain comparability and will make your decisions sharper.
What to write in your sheet
- Inputs: ad spend, promo spend, agency fees, acquisition salaries, creative costs, number of new customers, revenue, cost of goods sold, refunds, taxes collected, orders per customer, active months.
- Outputs: media-only CAC, fully loaded CAC, LTV over your chosen horizon, payback period, LTV to CAC comparison, CAC by channel.
When the sticky note asks again, you will have an answer you trust. Not perfect. Just reliable enough to move budget with confidence, pause a channel that is not paying back or lean into what clearly is.





