Retail Planby RetailNorthstar

How-to guides

Practical, step-by-step guides for apparel and retail planning — free, vendor-neutral, and paired with the tools and templates you can use to apply them.

How to set open-to-buy (step by step)

The open-to-buy formula, a worked apparel example, what negative OTB means, and how to keep it aligned to receipts and POs.

How to build a T&A calendar

Map every production milestone backward from the in-store date, with an owner and lead time on each step, so a slip surfaces the moment it happens.

What is a WSSI?

What the weekly sales, stock & intake plan is, the three lines it tracks, and the identity behind it: closing stock = opening stock + intake − sales.

How to read a WSSI, week by week

An operational walkthrough on a worked 12-week grid — the cover line, finding the stock-out and overstock weeks, phasing intake, and when the grid is lying to you.

OTB vs WSSI: what’s the difference?

How the open-to-buy budget and the weekly trading view differ, when to reach for each, and why most planning teams end up needing both.

How to build a buy plan

Turn OTB, assortment decisions, and demand assumptions into a line-by-line buy — with costs, margin, channels, and delivery timing attached.

How to calculate size curves

How to build size ratios from history and translate total style/colour demand into size-level buying quantities that match how a style actually sells.

Line plan vs assortment plan

What each plan decides — the range you will offer versus where it goes and in what depth — and how the two connect to buying and production.

Retail math formulas

A practical formula library covering OTB, sell-through, GMROI, inventory turnover, markdown, margin, and weeks of supply, each with a worked example.

Looking for analysis and best practices? See Insights.