Retail Math Formulas for Apparel Brands
The retail math apparel planners, buyers, allocators and executives work from — with live calculators, illustrative channel ranges, and worked examples.
Standalone pages, one per cut. The grid further down filters the same formulas in place.
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 worked example.
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 of apparel planning. 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 reading is 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 has to carry heavier markdown exposure. Sixteen of the formulas here also carry illustrative channel ranges — reference points, not a published benchmark.
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 get an interpretation of the result to check against your own targets.
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.
No credit card. No commitments.
Connected merchandise planning — live in weeks, not quarters.