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Module 08 / Lesson 48 · Read, apply, check
Calculate acquisition economics with consistent denominators and distinguish revenue return from profit.
Average cost per click is advertising spend divided by clicks. Click-to-conversion rate is conversions divided by clicks when that is the chosen funnel. Cost per conversion is spend divided by conversions. Label the event and period: a lead, a purchase and a new customer are different denominators. Mixing them can make a weak campaign appear efficient.
Customer acquisition cost should state which costs and customers are included. Media-only cost per new customer excludes creative, agency, sales and other acquisition expenses. A fully loaded estimate may include relevant costs across channels. Use comparable definitions across periods and distinguish new customers from returning purchasers before making an allocation or reporting improvement.
Return on ad spend is attributed revenue divided by ad spend. It is a revenue ratio, not a profit calculation. Products, fulfillment, refunds, discounts and other variable costs affect contribution. A high revenue return can still be uneconomic. State whether revenue is gross or net and whether the observed purchases are likely to be incremental.
Change one assumption at a time to see how economics respond. Higher click costs or a lower qualified conversion rate can reverse a promising result. Lifetime value needs a credible retention and margin model, not an optimistic revenue guess. Plan cash needs and a stopping condition before increasing spend, especially when customer payback takes months.
Change spend, clicks and purchases in the calculator below. Values are hypothetical.
Spend ÷ clicks; purchases ÷ clicks × 100.
Revenue ÷ spend; revenue less supply costs and media spend.
Purchases are not necessarily new or incremental customers. Other acquisition costs remain excluded.
Hypothetical example: a campaign spends $2,000 for 1,000 clicks. Fifty purchases produce $6,000 in net revenue, and forty buyers are new customers. Average CPC is $2; purchase conversion rate is 5%; cost per purchase is $40; media-only cost per new customer is $50; revenue ROAS is 3.0. If product and fulfillment costs total $3,600, contribution before advertising is $2,400. Subtracting the $2,000 media spend leaves $400 before creative, management and other costs. This calculation still uses attributed sales, so it does not prove that all forty new customers were caused by the campaign. The director records these definitions and tests a lower conversion-rate scenario before deciding whether the small remaining contribution can support more spending.
A report labels $6,000 revenue minus $2,000 advertising as $4,000 profit. It omits the cost of supplying the orders and mixes returning purchasers with new customers. The arithmetic is simple but the meaning is wrong. A useful review separates revenue, contribution and acquisition expenses, labels each denominator and explains the attribution limitation before presenting the result as evidence for a larger budget.
Misconception: a 3x ROAS always means a profitable campaign. Correction: the break-even revenue return depends on contribution margin and other costs. Revenue ratios cannot replace a model of what the business retains from each additional sale.
Small samples, delayed refunds and long sales cycles make early economics provisional. Use consistent cohorts and observation windows, update immature estimates and avoid presenting lifetime value as a settled fact before retention evidence exists.
Do this today · 25 minutes
Build a five-line model using spend, clicks, completed purchases, new customers and net revenue. Add variable fulfillment costs, calculate the ratios and write exactly which costs are still excluded from the resulting contribution.
Use an authorized page or campaign relevant to this lesson, or work entirely from the illustrative sample below. Record proposed changes as drafts until they are approved and implemented.
Spend is 1,000; clicks 500; purchases 20; new customers 10; revenue 4,000; variable fulfillment cost 2,800.
Before: “4.0 ROAS means fourfold profit.”
After: 4.0 revenue/spend ratio; 200 remains after the specified media and fulfillment costs.
Notes stay in this browser. Download a copy to keep them.
Replace illustrative figures with consistent business definitions and reconcile them with the finance owner before decisions.
Before you move on
A campaign spends $2,000, records 1,000 clicks and 50 purchases, and attributes $6,000 net revenue to those purchases. Product and fulfillment costs are $3,600. Which statement correctly describes the result before other costs and any incrementality adjustment?
Next lesson →Lesson edition 2 · References reviewed 14 October 2026 · Practical exercise reviewed 15 October 2026. Examples are illustrative teaching scenarios.
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