Why weekly margin review matters more than weekly revenue review
Revenue is an output. Margin is a decision. Seeing that revenue was 120,000 euros this week tells you that customers bought from you. Seeing that your contribution margin was 34 percent this week tells you whether you made money doing it. Revenue without margin context is noise.
Weekly margin review catches problems early. A contribution margin that drops from 38 percent to 31 percent over three weeks is a signal. It might mean rising COGS from a freight rate increase. It might mean a promotional campaign with higher discounts than planned. It might mean a channel mix shift toward higher-CAC channels. All three require different responses and all three are visible in weekly margin data before they appear in quarterly P&L reviews.
The five metrics and how to read them
Customer Acquisition Cost by channel, updated weekly using Shopify order data and actual ad spend. Compare week over week and against a rolling 8-week average. A spike above the 8-week average by more than 20 percent is worth investigating immediately.
Contribution margin per order, not blended but broken out by channel. A declining trend in any single channel signals either rising CAC, rising return rates, or product mix shift toward lower-margin SKUs.
New versus returning customer revenue split. If returning customer revenue is growing faster than new customer revenue, your business is building on a healthier foundation. If new customer revenue is growing faster, you are increasingly dependent on acquisition to maintain revenue.
Email list net growth (subscribers added minus subscribers lost). List decay faster than list growth means your most profitable channel is shrinking. This is a leading indicator of revenue problems 3 to 6 months forward.
Average order value trend by channel, not blended. AOV is affected by promotions, product mix, and upsell performance. A declining AOV on a high-margin channel might mean your upsell strategy is weakening. A rising AOV on a low-margin channel might be masking contribution margin problems.
Building the weekly review habit
The weekly review should take 30 minutes maximum. Build a simple dashboard that pulls these five metrics automatically from Shopify, your ad platforms, and your email ESP. The goal is not deep analysis. The goal is pattern recognition: what changed this week compared to last week and the 8-week average?
Set thresholds for each metric that trigger a closer look. CAC up 25 percent week over week triggers a channel audit. Contribution margin down 3 percentage points triggers a COGS and discount review. Declining these reviews to monthly guarantees you will miss problems that a weekly look would catch in time to fix.
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