Your Ad Platform Knows You'll Never Check the Maths

Meta said one campaign made £47,000 last month.

Total bank revenue from all sources was £31,000.

How Meta and Google double-count Shopify conversions

Someone is lying. And it isn't your bank.

This isn't a rounding error. This is platform attribution doing exactly what it was designed to do — making the platform look as effective as possible so you keep spending.

Here's how the maths breaks. Meta counts a sale if someone saw your ad and bought within 7 days, or clicked and bought within 28 days. Google does the same. TikTok does the same. If a customer saw a Meta ad on Monday, clicked a Google ad on Wednesday, and bought on Friday, all three platforms claim that sale. Your total "attributed revenue" across platforms is routinely 40–60% higher than your actual revenue.

Why last-click attribution overstates channel ROAS

You know this intellectually. You've heard it before. But you're still making budget decisions based on platform-reported ROAS because it's the number that's easiest to see.

The real number — your blended ROAS across all channels measured against bank-cleared revenue — is almost always lower. Sometimes dramatically lower. A brand seeing 4.2× ROAS in Meta might be running at 2.1× blended. That's the difference between a profitable acquisition channel and an expensive one.

The platforms aren't going to fix this. Attribution inflation isn't a bug. It's the business model. The more effective Meta looks, the more you spend on Meta. The incentive structure is working exactly as intended — just not in your favour.

First-party attribution for Shopify DTC brands

The fix is measuring what actually happened. Total ad spend across all channels. Total bank-cleared revenue. That gives you your true blended ROAS. Then layer in COGS, returns, fulfilment, and payment processing to get contribution margin per channel. That's the number that tells you whether your ad spend is actually generating profit — or just generating dashboard metrics that make you feel good about losing money.