Free retail planning calculators
Vendor-neutral retail math, free and no sign-up — open-to-buy, sell-through, GMROI, and lead-time / on-time-delivery. Each shows the formula and how to use it.
Size the opportunity and pressure-test the buy before you commit.
ROI / Margin Opportunity Calculator →
Size the margin recovered from fewer markdowns and the working capital freed by faster turns — your targets.
- Best for
- Owners and finance leads
- Use when
- You want to size the margin and working capital a connected plan could free up.
Open-to-Buy (OTB) Calculator →
Retail dollars you can still receive this period — and whether you are overbought.
- Best for
- Buyers and planners
- Use when
- You need to understand how much inventory you can still buy for a period.
WSSI Calculator →
Weekly Sales, Stock & Intake — project closing stock and weeks of cover.
- Best for
- Merchandisers and planners
- Use when
- You need to project closing stock and weeks of cover for a period.
Lead-Time / On-Time-Delivery Calculator →
Project an order’s arrival against the in-store date and see the slip risk.
- Best for
- Sourcing and production teams
- Use when
- You need to check whether an order will land before its in-store date.
Check how the inventory you already own is performing against plan.
Sell-Through Rate Calculator →
The share of received units that have sold — reorder or markdown signal.
- Best for
- Buyers and planners
- Use when
- You want a reorder-or-markdown read on how a style is selling through.
GMROI Calculator →
Gross-margin dollars earned per dollar of inventory at cost.
- Best for
- Planners and finance leads
- Use when
- You want to measure the margin return on each dollar of inventory held.
Initial Markup (IMU) Calculator →
The first markup on a style — and the margin that survives your markdowns.
- Best for
- Buyers, planners, and finance leads
- Use when
- You are setting a price and want to leave room for markdowns and still hit margin.
Inventory Turnover Calculator →
How many times inventory sells through and is replaced over a period.
- Best for
- Planners and finance leads
- Use when
- You want to see how quickly inventory cycles relative to plan.
Weeks of Supply Calculator →
How many weeks current stock will last at the recent sales rate.
- Best for
- Merchandisers and planners
- Use when
- You need to know how long current stock will cover demand.
Stock-to-Sales Ratio Calculator →
BOM stock per unit of period sales — the multiplier behind BOM stock targets.
- Best for
- Merchandisers and planners
- Use when
- You are setting BOM stock targets or reading cover against demand.
The apparel-specific math behind a size-aware, margin-aware buy.
Size Curve Calculator →
Turn sales history into the size distribution to buy by.
- Best for
- Buyers and allocators
- Use when
- You need to split a buy across sizes based on demand.
Markdown Calculator →
The markdown percentage, sale price, and margin impact of a price cut.
- Best for
- Buyers and planners
- Use when
- You need to work out the price and margin impact of a markdown.
Sell-In & Bookings Calculator →
Wholesale booking attainment (booked vs. plan) and fill rate (shipped vs. booked).
- Best for
- Wholesale and sales teams
- Use when
- You need to track booking attainment and fill rate against plan.
Landed Cost & Margin Calculator →
True landed cost from FOB + freight + duty, and the gross margin at a target retail price.
- Best for
- Sourcing and finance leads
- Use when
- You need true landed cost and the margin at a target retail price.
These do the math one figure at a time. RetailNorthstar runs it across every style, channel, and season — connected to one plan.
Book a Demo →