You will build a spreadsheet that calculates acquisition cost, first-year value and payback by channel from your own data.
Farah worked out her acquisition cost, customer value and payback in lessons 8.1 to 8.3 on the back of an envelope, then on a notes app, then in a spreadsheet tab called "Sheet3". When her business partner asked to see the working a month later, she could not find half of it, and the figures she did find no longer matched the latest orders.
This exercise turns that scattered working into one sheet you can update every month in a few minutes. It calculates acquisition cost, first-year value and payback for each channel, with every input and estimate visible. The worked example uses Farah's figures for one quarter, all of them example numbers.
Before you open a spreadsheet, collect the raw numbers for one period, such as last quarter.
Spend comes from the ad platforms' billing pages and from invoices: ad spend per platform, tools, freelancers, agency fees. Customers come from your source of truth: your shop platform, CRM or booking system, counting first-time customers only. Order values and orders per customer also come from your shop or booking records. Gross margin comes from your accounts or supplier invoices, and if you only have a rough figure, that is fine as long as you label it.
For per-channel customer counts, use your best attribution view from module 5, usually GA4 or your shop platform's own source report. Also pull the answers to your self-reported source question from lesson 5.3, counted by channel for the same customers.
Create a spreadsheet with two tabs: Inputs and Calculations. Keeping them apart means you only ever type into one place, and the formulas on the other tab stay untouched.
On the Inputs tab, give each channel a row and give the columns these headings: channel, ad spend, share of other costs, new customers (tracked), new customers (self-reported), average order value, orders per year and gross margin. Add a column called "source and notes" at the end, and use it.
Farah's two rows for the quarter:
Google search: ad spend S$1,440, share of other costs S$480, 40 new customers tracked, 32 self-reported, average order S$100, 2.4 orders a year, gross margin 40 percent.
Meta ads: ad spend S$1,800, share of other costs S$600, 60 new customers tracked, 45 self-reported, average order S$75, 2.0 orders a year, gross margin 40 percent.
The "share of other costs" is her tools, a freelance designer and an estimate of her own time, split between the two channels in proportion to ad spend. It is the softest number on the sheet, so its cell is shaded yellow with a note: "estimate, split by ad spend". Gross margin gets the same treatment, with "owner's estimate from supplier invoices".
Below the channel rows, add one line for the whole business: total marketing and sales costs for the quarter and total new customers. For Farah, S$5,500 and 160, including customers from email, search results and referrals that no ad paid for.
On the Calculations tab, each channel gets a row that reads from the Inputs tab. Use formulas that point at the input cells, so a change on Inputs flows through.
Acquisition cost is ad spend plus share of other costs, divided by new customers. For Google search: S$1,440 plus S$480 is S$1,920, divided by 40, which is S$48. For Meta: S$1,800 plus S$600 is S$2,400, divided by 60, which is S$40.
First-year value is average order value times orders per year times gross margin. Google: S$100 times 2.4 times 40 percent is S$96. Meta: S$75 times 2.0 times 40 percent is S$60.
Monthly margin is first-year value divided by 12: S$8 for Google, S$5 for Meta. Payback is acquisition cost divided by monthly margin: 6 months for Google, 8 for Meta.
Add a blended row at the top, using the whole-business line: S$5,500 divided by 160 new customers is about S$34 per customer. It is lower than either channel because it includes customers who cost no ad money, and it is the anchor figure from lesson 8.1.
Now add a second set of columns that repeats acquisition cost and payback using the self-reported customer counts instead of the tracked ones. This is the second view of channels from module 5.
For Google, S$1,920 divided by 32 self-reported customers is S$60, and payback becomes S$60 divided by S$8, or 7.5 months. For Meta, S$2,400 divided by 45 is about S$53, with payback of about 10.7 months.
The two views will rarely agree. Where they point the same way, as here, with Google paying back faster in both, Farah can act with more confidence. Where they disagree sharply, the sheet records the disagreement rather than hiding it.
A finished sheet has an Inputs tab with every number traced to a source, estimates shaded and explained, and a Calculations tab with acquisition cost, first-year value and payback by channel, a blended row, and a self-reported column alongside. Updating it next month means typing the new month's inputs and nothing else.
Farah's business partner read it in five minutes and asked one question, about the yellow cells. That is the right question. With your own sheet built the same way, the soft numbers are the first thing a reader sees.
Build a unit economics sheet with acquisition cost, first-year value and payback period for at least two channels, with inputs and estimates labelled.
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