Margin, Markup & Break-even Calculator

Pricing becomes confusing when several correct percentages describe the same sale. A product that costs 60 and sells for 100 earns 40 of gross profit. Its margin is 40% because profit is measured against the 100 of revenue. Its markup is 66.67% because the same profit is measured against the 60 of cost. Neither number is wrong, but substituting one for the other can quietly erase the profit a business expected.

The Margin, Markup & Break-even Calculator keeps those bases explicit. Its first mode gives gross profit, margin, and markup from cost and selling price. Target-price mode reverses the formulas, so a seller can start with a required 40% margin and discover that a 60 cost needs a 100 selling price. Choosing a 40% markup instead produces 84, a materially different answer. The tool can also solve the allowable cost from a known selling price and desired percentage, which is useful during sourcing and supplier negotiation.

Break-even mode adds the operating context that a per-unit margin alone cannot supply. Contribution per unit is selling price minus variable cost. Dividing fixed costs by contribution shows the exact theoretical break-even volume, while the operational answer rounds up to a whole unit. The contribution margin ratio also converts fixed costs into break-even revenue. This helps founders, retailers, consultants, and creators connect individual sales to rent, salaries, software, equipment, and other costs that exist even when nothing is sold.

Real transactions rarely stop at cost and list price, so the advanced mode follows the money through a discount, marketplace percentage, payment-processing percentage, fixed transaction fee, shipping, packaging, and tax. It separates the amount a customer pays, tax collected, fees, revenue before cost, total unit costs, and final profit. For tax included in price, the tax portion is backed out before revenue. For tax added on top, the customer payment rises while tax remains separate from business revenue. Marketplace and payment percentages are applied to the customer payment, an assumption stated beside the form because actual platforms may use a different base.

Saved products make the calculator useful as a lightweight pricing notebook without creating an account. Rows are stored only in browser local storage and can be loaded for editing, duplicated for variants, deleted individually, cleared with confirmation, or exported to CSV. Sensitivity analysis then answers the next question: what happens if price, cost, fee rate, or volume moves? Five scenarios around the baseline show profit per unit, margin, total profit after fixed costs, and break-even units. The baseline is highlighted, and the table scrolls horizontally on small screens instead of compressing figures into unreadable cells.

All calculation functions are client-side, reusable, and tested independently of the interface. Results are rounded consistently for display while formulas retain enough precision to avoid obvious floating-point artifacts. The calculator is currency-neutral: the selector formats numbers but never fetches exchange rates or changes an amount. It is a planning aid, not a substitute for a platform statement, accountant, tax adviser, or jurisdiction-specific rules.

Core formulas

Gross profit is selling price − cost. Margin uses selling price as the denominator: profit ÷ selling price × 100. Markup uses cost: profit ÷ cost × 100. To reach a target margin, selling price is cost ÷ (1 − margin). To reach a target markup, it is cost × (1 + markup). Percentages are converted to decimals inside these formulas.

Break-even formulas

Contribution per unit is selling price − variable cost. Break-even units are fixed costs ÷ contribution per unit. The calculator shows the exact quotient and rounds the practical unit count upward. Contribution margin ratio is contribution ÷ selling price, and break-even revenue is fixed costs ÷ contribution ratio.

Discount, tax, and fee order

The advanced mode first applies the discount. Added tax increases the customer payment; included tax is extracted by dividing the tax-inclusive price by 1 + tax rate. Percentage fees use the customer payment as their base, then fixed fees are added. Net revenue is revenue before tax minus fees. Profit is net revenue minus product cost, shipping, and packaging. Margin after fees uses net revenue as its base; markup uses total unit costs.

The calculator models one product or scenario at a time and assumes the entered values stay constant within that calculation. It does not model tiered marketplace fees, refunds, chargebacks, inventory carrying cost, income tax, multi-product sales mix, currency conversion, exchange-rate risk, or time value of money. Sensitivity analysis changes one selected input around a baseline; it is not a probability forecast. Tax and fee rules vary, so reconcile important decisions with current contracts, platform statements, and professional advice.

All modes call pure functions in a standalone ES module. Inputs are converted to finite numbers, checked against mode-specific bounds, and guarded against zero or negative denominators. Intermediate results are normalized to ten decimal places; currency output is locale formatted to two decimals. Break-even whole units use Math.ceil on the normalized exact result. CSV escaping follows RFC-style quoting for commas, quotes, and line breaks and adds a UTF-8 byte-order mark during browser download for spreadsheet compatibility. Saved-product JSON is parsed defensively and capped at 200 valid rows.

Margin answers “what percentage of revenue remains as profit?” Markup answers “what percentage was added to cost?” Contribution margin answers “how much of each sale remains to cover fixed costs and profit?” Net margin after fees in this tool uses revenue remaining after tax and transaction fees, then compares final unit profit with that net revenue. Choose the measure that matches the decision instead of comparing percentages with different denominators.

Independent sellers, marketplace merchants, retailers, wholesalers, makers, consultants, creators, small-business owners, product managers, and students who need transparent pricing math. It is especially useful when a simple margin calculator is too narrow because discounts, processor fees, shipping, packaging, taxes, fixed overhead, and scenario comparisons affect the real decision.