A practical guide to the numbers behind the store.
Short guides for choosing and using ecommerce profitability, advertising, pricing, and inventory calculators.
Use these guides as a short checklist for choosing the right calculator and interpreting the result. Each guide links to the working tool rather than asking you to read a long article first.
Start with unit economics
Before spending more on traffic, know what one order contributes after product cost, fulfillment, platform fees, and advertising. The profit margin calculator is the best starting point.
Include inbound freight, duties, and packaging in the product cost. A supplier quote alone usually understates the real cost.
Include both marketplace commission and payment processing. Fixed fees matter more on low-priced orders.
If you do not know the cost per order yet, test a pessimistic case before scaling spend.
Set an advertising floor
A target ROAS should be tied to contribution margin, not just revenue. Use the break-even ROAS calculator to find the minimum return required before an order contributes to overhead.
Price by margin, not instinct
A markup is applied to cost; a margin is a share of selling price. The product pricing calculator and markup versus margin calculator keep those two numbers separate.
Check inventory before the stockout
Reorder timing should include supplier lead time and a buffer for demand variation. Use the reorder point calculator for a simple trigger and the turnover calculator to review how much cash is tied up in stock.
Review the downside before the upside
Run a discount, ad spend, or pricing change through the calculator before approving it. A result is not a guarantee, but it makes the assumptions visible enough to challenge.