Retail Math Formulas for Apparel Brands
The retail math every apparel planner, buyer, allocator, merchandiser, and executive uses — with live calculators, benchmark ranges by channel, and worked apparel examples.
Plan → Buy → Allocate → Measure — the formulas, connected.
Each stage's math feeds the next. OTB sizes the buy; the buy populates the allocation; allocation drives sell-through; sell-through calibrates the next OTB. Click any formula to see its live calculator and channel benchmarks.
The loop closes. Measurement formulas (sell-through, WOS, markdown) feed back into the next period's plan — calibrating OTB, receipt timing, and buy depth. A connected system runs this loop weekly; a spreadsheet runs it once a season.
Take the formulas with you.
Frequently asked
What are the most important retail math formulas for apparel brands?
Open-to-buy (OTB), initial markup (IMU), maintained markup (MMU), sell-through rate, GMROI, weeks of supply (WOS), inventory turns, fill rate, and markdown percent are the core formulas every apparel planning team uses. They govern how much to buy, at what cost, how fast inventory moves, and how much margin survives.
How are apparel retail math formulas different from general retail formulas?
The formulas are the same. The benchmark ranges are not. Apparel sell-through is split between full-price and total, size curves create depth-by-size complexity spreadsheet-based retail cannot model, and seasonal IMU targets run higher because markdown exposure is heavier. Every formula on this page includes apparel-specific benchmark ranges.
Why do apparel brands need a calculator on every formula?
Static equations are a reference. Live calculators turn the reference into a decision tool — plug in your plan numbers and see the result against the apparel benchmark range for your channel.
Turn the math into action.
RetailNorthstar calculates, tracks, and flags these metrics inside a connected apparel planning workflow — so teams act on them instead of rebuilding them in spreadsheets.