How our calculators work

Use these tools to explore pricing and advertising decisions under your own assumptions. They estimate unit economics, not your company's full accounts or tax position.

Last substantive update: 2026-10-01.

Use consistent inputs

• Use one currency throughout a scenario. The currency selector changes display symbols only; it does not convert exchange rates.
• Use revenue excluding VAT or sales tax, and keep costs on a comparable basis. Reconcile any taxes or shipping revenue included in platform conversion values before comparing ROAS.
• For campaign performance, use ad spend and attributed revenue for the same period and attribution basis. Platforms may claim overlapping conversions; reported revenue is not necessarily incremental revenue.
• For TACoS, use total sales including ad-attributed and other sales on the same basis. Total sales must not be below ad sales.
• Enter your own payment and marketplace fees. Default values illustrate a scenario; SellerUtils does not retrieve current platform rates.

Formulas and profit definitions

In the formulas below, P is price or average order value, C is the sum of entered per-order costs, m = (P − C) ÷ P, and t is your target margin. Enter percentages such as 40 in the form; formulas use the decimal 0.40.

Gross margin, contribution margin and net margin answer different questions. A positive contribution after ads can still leave a business unprofitable after rent, salaries, subscriptions and other overhead. Include a suitable allowance in your planning; the tools do not automatically calculate those expenses.

Refunds, repeat orders and other limits

Refunds: the cost model deducts P × the share of revenue refunded. This is not the percentage of orders returned. It retains the original product, shipping and fee costs, and does not separately model recovered inventory, refunded processing fees or return shipping. Adjust your cost inputs consistently and avoid double counting refunded revenue.

Repeat orders: the CPA tool estimates an ad-only acquisition limit as contribution per order × average lifetime orders per customer. It assumes identical contribution on repeat orders, no extra acquisition or retention spend and no discounting of future cash flows. Later profit cannot pay today's bills immediately.

CPA versus CAC: CPA is cost per conversion; CAC is cost per new customer. They coincide only when the conversion is a new customer's first order and the cost basis matches. Fully loaded CAC can include sales and marketing overhead, which our ad-only scenario does not measure.

TACoS: if spend is unchanged and TACoS falls, total sales have increased. Organic growth cannot be inferred without examining ad-attributed sales and attribution consistency.

Input boundaries: ad spend, selling price and product cost in the gross-margin tool must be positive. Percentage inputs must be below 100%; a target margin can be zero. Undefined ratios and unreachable targets are shown as explanations rather than usable targets.

The ACoS tool calculates from ad spend and sales. Its conversion table is a reference, not a separate direct-entry ACoS/ROAS converter. Target ROAS is a planning threshold, not a guarantee that an ad platform will achieve it.

A reproducible cost example

For a $50 order, with $15 product cost, $5 shipping, $1 other cost, a 2.9% payment fee and a $0.30 fixed payment fee, entered costs total $22.75. Contribution before ads is $27.25, or 54.5%. The break-even ROAS is 1 ÷ 0.545 ≈ 1.83.

Keeping a 20% contribution margin after ads requires 1 ÷ (0.545 − 0.20) ≈ 2.90 ROAS. A zero target margin returns the same 1.83 break-even value. These are examples, not recommended fee rates or advertising targets.

Formula tests check worked examples and boundary cases. Display values are rounded; calculations use unrounded values. Material formula, assumption and content changes update the page date and sitemap together.

Try the break-even ROAS example or choose another calculator.

Your inputs, shared links and usage data

Calculations run in your browser. Input values are reflected in the address bar so a scenario can be reopened. A copied link includes those values; anyone with the link can read them. Browser history and hosting access logs may also contain the requested URL. Do not share figures you want to keep private.

Copied links omit campaign parameters. Address-bar updates preserve incoming campaign parameters so they remain available for attribution. A local tab session stores a broad source category and which tools you viewed or used; it expires after 30 minutes without a measured interaction. It contains no calculation amounts.

Usage events contain only a page identifier, entry page, broad source category and event name. When a measurement receiver is configured, these events can be sent to it without input values, full URLs or referrer strings. The receiver can still observe normal connection information such as an IP address. No measurement request is sent when no receiver is configured.

Opening a default example or shared scenario does not count as a completed calculation. We count effective use after a person changes a numeric input and a valid main result remains for a short pause, once per tool per tab session. Currency changes and resets alone do not count.

Platform definitions and further reading

Platform documentation explains reported metrics and bidding behavior. Our contribution model and its assumptions are described above; these links do not imply affiliation or endorsement.

• Amazon Ads: advertising cost of sales
• Google Ads: Target ROAS bidding
• Google Ads: conversion values

Sources checked October 1, 2026. Results are estimates for planning and are not financial advice.