Build the contribution margin waterfall one order at a time, from average order value down to CM3 after acquisition cost. Then see the marketing cost of sale your margin can actually carry.
Excluding VAT and excluding any shipping fee the customer pays.
AOV must be above zero.
Enter at least one new customer order.
Retention, CRM and any retargeting aimed at your existing base. Stripped out before CAC.
Existing customer spend cannot exceed total marketing cost.
New customer revenue as a share of total revenue, new plus existing.
Leave at zero to calculate it from the numbers above.