Start with revenue and the period
Choose a clear period for the review, such as a calendar month, and use revenue and expenses from that same period. Be consistent about whether revenue includes shipping charged to customers, discounts, refunds or taxes collected on behalf of authorities. The correct accounting presentation depends on your business and applicable rules. For an operational estimate, write down the definition you are using so that comparisons between months remain consistent.
Track product and inventory costs
Record the cost of the goods sold during the period, not simply every purchase made during the month. Inventory purchased may remain unsold at the end of the period, so cash paid to suppliers and cost of goods sold are not always the same measure. For manufactured products, consider materials and production costs under a consistent method. For imported products, landed cost can provide a more complete unit-cost basis than the supplier price alone.
Include fulfillment and shipping
Fulfillment costs may include packaging, pick-and-pack, warehouse services, shipping labels, delivery charges paid by the business and other order-handling expenses. Separate shipping collected from customers from shipping paid to carriers. If a store offers free shipping, the business may still be paying a carrier cost for every order. Review actual invoices and average cost per order rather than using an outdated estimate.
Account for payment and marketplace fees
Payment processors and online marketplaces may charge percentage fees, fixed transaction amounts, listing fees or other service charges. The fee base can differ between providers and may include shipping or tax amounts. Use current statements or provider schedules to estimate the cost accurately. If the calculator input combines payment and marketplace fees into one amount, keep a separate record of the underlying components so that you can identify changes and avoid counting the same fee twice.
Measure advertising costs carefully
Advertising spend should be reviewed alongside the orders and revenue attributed to the same campaign and time window. Dividing ad spend by attributed orders can provide an estimated advertising cost per order. Attribution is imperfect, and platform reporting may differ across channels or overlap. Avoid assuming every order would disappear without an advertisement, and consider repeat purchases or organic demand when interpreting campaign results. Use consistent definitions when comparing campaigns.
Include refunds, returns and overhead
Refunds and returns can reduce realized revenue and may add shipping, handling, restocking or damaged-stock costs. Record them consistently and avoid subtracting the same refund in more than one place. Monthly overhead may include software, rent, salaries, subscriptions and other recurring expenses. Decide whether the review is measuring contribution before overhead or estimated profit after overhead. The distinction should be visible in the report and consistent across periods.
Understand profit per order and net margin
Estimated profit for a period can be divided by the number of orders to calculate average profit per order. This average does not mean every order earns the same amount; product mix, discounts, shipping destinations and return rates can vary. Net margin expresses the profit measure divided by revenue, multiplied by 100. Make sure the costs included in the numerator match the label. A product-level estimate is not automatically the same as a company's formal net profit margin.
What break-even ROAS tells you
Return on ad spend compares revenue attributed to advertising with advertising cost. Break-even ROAS estimates the revenue-to-ad-spend ratio needed for advertising to cover its cost after the other modeled costs are considered. It is not a complete measure of business profitability. A campaign can show a strong ROAS while the store loses money if product costs, fulfillment, refunds or overhead are high. Use contribution and margin alongside ROAS when assessing campaigns.
Build a useful monthly review
Compare the current period with previous months and investigate changes in average order value, order volume, product cost, fulfillment cost, fee rate, refund rate and advertising efficiency. A shift in product mix can change margin even when revenue increases. Use the Ecommerce Profit Calculator to organize the main inputs, then check the result against accounting records. Pair it with the Selling Price Calculator for product-level pricing and the Break-even Calculator for fixed-cost planning.
Limitations and next steps
A simple calculator cannot automatically account for every tax, inventory accounting adjustment, salary allocation, financing cost, depreciation or one-off event. Its result depends on the numbers entered and the definitions chosen. Keep source records, review unusual items separately and consult a qualified accountant for formal reporting or tax decisions. Use estimates to identify questions and compare scenarios, not as a guarantee of future profit or a substitute for a complete set of accounts.