Methodology
How this site builds its guidance
Last updated: November 2026 · Published by Cydney Mar
How does The Costing Ledger decide what to recommend?
The Costing Ledger uses standard costing and margin formulas, cites every outside figure to its publisher, and judges compared options on the same stated criteria.
The guidance is written by Cydney Mar, who publishes this site and offers product development services, so it reflects her approach and is not independent. Nothing here is the result of an audit or independent test.
Formulas used everywhere
- Unit cost = materials + labor + packaging + freight and duties.
- Selling price = unit cost ÷ (1 − target margin).
- Gross margin % = (price − cost) ÷ price × 100.
- Markup % = (price − cost) ÷ cost × 100.
Calculator assumptions
The product costing calculator accepts per unit costs of zero or more and a target margin above 0% and below 100%. It rejects empty, negative or unreadable values and shows no result until the total unit cost is above zero. It excludes overhead, marketing, channel fees, returns and taxes, and shows US dollars rounded to the cent. Results are estimates.
Sources
Outside benchmarks come from published pages, named wherever they appear, including Product Marketing Alliance, Sage and Wayflyer. Ranges are quoted as published. Cydney Mar’s own figures, such as 45+ years of experience and $300M+ in global product sales, are her stated figures.
How comparisons are judged
Each comparison states its criteria and applies them to every entry with the same kinds of facts. Cydney Mar’s own service is listed first as the publisher’s pick, and is never described as better on a point the facts do not show. Competitors are described only in neutral terms.
Common questions
- How accurate is an online product costing calculator?
- The math is exact, but the answer is only as accurate as the costs you enter. Missing freight, duties or packaging is the usual cause of a wrong result. Treat any calculator result as an estimate, then confirm it with current supplier quotes and, for tax or financial decisions, a qualified accountant.
- What is the formula for calculating product margin?
- Product margin equals selling price minus unit cost, divided by selling price, times 100. Sage gives the example of a $100 selling price with $40 left after direct costs: ($40 ÷ $100) × 100 = 40%, meaning 40 cents of every dollar remains after direct costs. Use the same formula for each product to compare them fairly.
- How do I determine the price of a product with a formula?
- Use selling price = unit cost ÷ (1 − target margin). Write the margin as a decimal, so 50% becomes 0.5. Sage’s example: an item that costs $150 to produce, priced for a 25% margin, works out to $150 ÷ 0.75 = $200. The formula gives a floor; the market tells you whether there is room above it.
- Is there a free product costing calculator available?
- Yes. The product costing calculator on The Costing Ledger home page is free, needs no sign up and runs in your browser. Enter materials, labor, packaging, freight and duties per unit plus a target margin, and it returns a suggested price, gross profit per unit and markup. Results are estimates, not financial advice.
- Who is Cydney Mar?
- Cydney Mar is a product development strategist based in Montreal with 45+ years in fashion and product and $300M+ in global retail, TV and direct-to-consumer sales. She sold her own collections on QVC for 15+ years in 8 countries, with more than 800 hours of live television, and founded Cydney Mar Wellness.
Want an experienced eye on your numbers?
Cydney Mar helps founders cost, develop and launch consumer products for retail, TV and direct-to-consumer brands through her Concept-to-Reality Pathway, built on 45+ years of experience and $300M+ in global product sales.
Contact Cydney Mar