Retail Math Formulas by Category
The category cut of retail math groups every formula by the part of the business the number describes, rather than by the job title that runs it. It is the cut to use when you are diagnosing a problem instead of doing a task: a season that is missing margin sends you to the margin formulas, whoever owns them.
5 categories, 40 formulas. Each formula page carries the equation, a live calculator, and a worked apparel example. The same formulas are also available in the role cut, which groups them by the job that owns the decision.
How To Read The Category Cut
Each formula sits in exactly one category — the thing it measures, not the thing it influences. Markdown percent is a margin formula even though it moves sell-through, and weeks of supply is an inventory formula even though it is read off sales. One formula, one category, several roles.
That single assignment is what makes the categories useful as a diagnostic path. When a symptom shows up in one category, the formulas next to it are the ones that explain it: a turn problem lives beside the sell-through and plan-variance math, not beside the cost negotiation.
The top line read at the level decisions are made — category mix, achieved retail and unit cost, units and dollars per transaction, returns, and the gross-to-net bridge underneath reported sales.
How hard each inventory dollar works between receipt and sell-through: return on the margin those dollars earn, turn speed, and how far the plan has drifted from actual.
Period-against-period comparison — comparable store sales, which separates real expansion from calendar shifts and door-count changes.
What to buy, when receipts land, and how much cover sits behind the plan: open-to-buy, stock-to-sales, weeks of supply, receipt flow, BOP and EOP, safety stock and fill rate.
The profitability of the season from first cost to final markdown — initial and maintained markup, markdown, allowances, cost of goods, and target costing.
Diagnose the season, not the spreadsheet.
RetailNorthstar calculates and tracks this math inside a connected apparel planning workflow, so a margin question is answered in the plan rather than rebuilt in a new tab.
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Connected merchandise planning — live in weeks, not quarters.