Start with the sale
List the costs that change with each order: product cost, packaging, delivery subsidies, transaction fees, and a realistic returns allowance. Keep fixed costs separate. A product priced at 100 with cost 60 and 3% fees contributes 37 before fixed costs.
Then test advertising headroom
That 37% contribution margin implies a break-even ROAS before fixed costs of 1 ÷ 0.37, or about 2.70×. This threshold changes if discounts, shipping, returns, or fee rates change. Fixed costs require additional headroom. Use actual costs rather than a generic industry target.
Keep attribution consistent
Write down the reporting window, attribution model, and treatment of refunds before comparing results. A campaign platform and your accounting records may measure different things. Revenue attributed by two platforms can overlap; adding both totals can overstate sales.
Name a campaign once
Use a source such as newsletter, a medium such as email, and one campaign name such as winter_launch. Share this convention with anyone making links. Keep personal and confidential information out of URLs. Use the URL builder to preserve existing parameters and replace old UTM labels.
Decide what to improve
If contribution is negative, revisit pricing or cost before buying more traffic. If contribution is positive but campaign profit is negative, examine acquisition cost, attribution quality, and fixed costs. Recalculate with a downside scenario for lower revenue or higher returns. These tools perform arithmetic on your assumptions; they do not forecast demand.