Methodology
How our tools and figures are built
Published by Cydney Mar Last updated: November 2026
Every tool on The Cost Sheet uses standard per unit cost and margin formulas, and every outside number is credited to the page that published it.
The Cost Sheet is written and published by Cydney Mar. Its calculators use cost plus margin pricing on a variable, per unit cost. Its checklists group the costs and terms that change a product's price by channel. Nothing on the site is an audit, an independent study or a guarantee of results.
Which formulas do the calculators use?
Both calculators measure margin on the selling price and markup on cost. These are the only formulas in use across the product costing calculator, the margin calculator and the cost sheet template.
| Output | Formula |
|---|---|
| Unit cost | Sum of all per unit cost lines |
| Selling price | Unit cost / (1 minus target margin) |
| Gross profit per unit | Selling price minus unit cost |
| Gross margin | Gross profit / selling price |
| Markup on cost | Gross profit / unit cost |
| Markup to margin | Markup / (1 + markup) |
| Margin to markup | Margin / (1 minus margin) |
Input rules and sources
How inputs are checked
- Commas, a dollar sign and surrounding spaces are accepted.
- Empty, unreadable or negative figures are rejected with a message next to the field.
- Price and unit cost in the margin calculator must be above zero.
- A target margin must be at least 0% and below 100%.
- No result is shown until every required figure is valid.
- Results are estimates for planning, not financial, tax or legal advice.
Where outside numbers come from
Benchmarks such as published margin ranges come from named, linked pages, including Product Marketing Alliance, Sage, Zendesk, Wayflyer, Online Labels, Founderpath and Calculator Soup. Each is quoted with its full range and conditions and is never presented as Cydney Mar's own figure. Facts about Cydney Mar, such as 45+ years of experience and $300M+ in global product sales, are as stated on cydneymar.com.
How we chose what to include
Cost lines and checklist items were chosen for how directly they change the price a consumer product must carry, and how often they are left out when founders price from a factory quote alone. Channel content is compared on the same points for retail, TV shopping and direct to consumer, using general industry practice rather than any one partner's terms.
Everything here was written by Cydney Mar, who publishes this site and offers product development services. The site does not rank or review other businesses. Pages are reviewed when published figures or formulas change, and each page shows the month it was last updated.
Common questions
See all 48 questions in the FAQHow accurate is the calculator?
The arithmetic is exact, but the result is only as accurate as the costs you enter. It is an estimate for planning, not a financial, legal or tax decision. Use real supplier quotes, include freight and duties, and confirm final numbers with your accountant or a product development professional before committing to a price.
Which currency does the calculator use?
The calculator works in any currency as long as every figure you enter uses the same one. Results are shown with a dollar sign for readability. If a supplier quotes in a different currency, convert each quote at a realistic rate first, and consider adding a small allowance for exchange rate movement.
Who is The Cost Sheet for?
The Cost Sheet is for founders building consumer products for retail, TV shopping and direct to consumer channels who want to price with real numbers. It is published by Cydney Mar, a product development strategist with 45+ years of experience and $300M+ in global product sales across retail, TV and DTC.
What if my price comes out too high for the market?
If the calculated price is too high, change the cost, not the margin math. Options include simplifying materials or construction, changing packaging, ordering larger quantities, choosing a different channel, or repositioning the product for a buyer who values it more. A product development strategist can help find the change that protects both quality and margin.
Should I price with markup or margin?
Price with margin when you sell through retailers, TV partners or to investors who think in margin, and use markup only as a quick shortcut. Margin keeps your planning tied to the selling price, which is where discounts, partner shares and returns are calculated. The Cost Sheet tools show both, so you can speak to buyers in either language.
Want an expert on your numbers before you commit?
Cost and Margins is one stage of Cydney Mar's Concept-to-Reality Pathway, which takes founders from product clarity to prototypes, suppliers, production readiness and launch in retail, TV or DTC.