# How We Calculate: Sources and Method | RevenueWorks > Sources, formulas, price date and update schedule of our free calculators for website cost, ROAS, Shopify fees and margin. Source: https://revenueworks.ai/methodology Language: en --- [RevenueWorks](https://revenueworks.ai/)/[Tools and calculators](https://revenueworks.ai/tools)/Methodology # How we calculate **In short:** Shopify prices and fees come from shopify.com/de/preise (as of 7 Nov 2026). The website guide values are our own market estimate, not a study. ROAS, margin and break-even follow open formulas shown on each calculator page. We review the values at least once per quarter. Last updated: 2026-11-07 ## Principles - Every figure has a date and a source or is marked as an estimate. - Formulas are shown openly on the respective calculator page. - All prices are net unless the page says otherwise. - We do not give legal, tax or investment advice and no guarantee of results. ## Sources per calculator ### Shopify cost calculator and Shopify fees calculator Plans, card fees and surcharges come from [shopify.com/de/preise](https://www.shopify.com/de/preise), as of 7 Nov 2026. PayPal’s fees are a check value (2.99% plus €0.39) that you can change in the calculator. The Starter plan is no longer listed on the Shopify pricing page, so its values are not verified. ### Website cost calculator The ranges are our own estimate for the German-speaking market (net), split by type of website and provider. They are based on experience, not on a survey. The ranges and the factor for add-ons are visible in the page source. ### ROAS and break-even calculator Contribution margin per order = (1 − return rate) × (basket − cost of goods) − shipping and fees − return rate × cost per return. Break-even ROAS = basket ÷ contribution margin. Break-even CPA = contribution margin. ### Margin and profit calculator Net = gross ÷ (1 + VAT). Profit = net − cost of goods − shipping − payment fee − advertising − return loss. Margin = profit ÷ net. Markup = (net − cost of goods) ÷ cost of goods. ## Updates We review the values at least once per quarter and whenever a price change becomes known. The “Last updated” date is shown at the top of each page and in the schema (dateModified). ## Report an error Spotted a wrong figure? Write to hello@revenueworks.ai. We check and correct it in writing. ## Frequently asked questions Where do the Shopify prices come from? From shopify.com/de/preise (https://www.shopify.com/de/preise), prices in euros for Germany, as of 7 Nov 2026. How current are the values? We review them at least once per quarter and whenever a price change becomes known. The date is shown with each answer. Are the website guide values a study? No. They are typical market ranges that we estimate from experience. They are not representative and do not replace a quote. Do you store my inputs? No. The calculators run entirely in your browser. 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