Assortment Planning Calculator
Options against depth, for a fixed budget.
Work out how many options a budget supports at a given depth, or how deep you can go across a fixed number of options.
Units per option
100
2000 units in total
Options × depth × unit cost is the budget, so fixing any two settles the third. Newness argues for breadth and shallow depth so a miss costs little; predictable repeat lines argue for depth. Keeping some budget uncommitted for in-season reorders is usually worth more than spending all of it up front.
How the Assortment Planning Calculator works
Options times depth times unit cost is the budget, so fixing any two settles the third. That makes assortment planning a single explicit trade: more choice with less of each, or fewer choices bought deep enough to actually stay in stock. Buyers argue about it constantly and rarely write the arithmetic down.
Also known as: range plan calculator · breadth vs depth calculator
Breadth against depth, on a fixed budget
Options times depth times unit cost equals the budget. Fix any two and the third follows, which makes assortment planning an explicit trade rather than a matter of taste.
Breadth is choice: more options, each bought shallow. It spreads fashion risk, because any single miss costs little, and it suits categories where demand is hard to predict. Depth is availability: fewer options bought deep enough to stay in stock in every size for the whole season.
The failure mode of too much breadth is a range that looks picked-over within a week, because three units of each option is out of stock in the middle sizes almost immediately.
A worked example
A 50,000 budget at a 25 average cost buys 2,000 units. Across 20 options that is 100 units each — enough for a five-size curve to hold up for a season. Across 60 options it is 33 units each, which is six or seven per size and out of stock in medium within days.
Turning it round: if you need 100 units per option for availability, the budget supports 20 options. Wanting 30 options at that depth needs 75,000, and knowing that before the range is designed is more useful than discovering it during the buy.
Where the answer misleads
Averages hide the shape. A range with a few deep core lines and many shallow fashion options can have the same average depth as one that is uniformly mediocre, and behave completely differently. Plan the core and the fashion separately.
The model also assumes the whole budget is committed up front. Holding a portion back for in-season reorders on what actually sells is usually worth more than any improvement in the initial split, because it replaces a guess with information.
Finally, unit cost is not independent of quantity. Deeper buys often unlock better pricing, which shifts the arithmetic in favour of depth in a way a fixed cost per unit cannot show.
Not financial advice. Marketplace fees change, and they vary by country, plan and seller status. Every rate here is an editable default, not a quoted price, check the platform's current fee schedule before you price a product against it. This is not tax or business advice.
Frequently asked questions
What is breadth versus depth?
Breadth is the number of different options — styles and colourways — and depth is how many units of each. A fixed budget buys one at the expense of the other, and the right balance depends on how predictable your demand is.
How many options should I buy?
Enough that the range looks considered, few enough that each has real depth. A rail of forty options at three units each is out of stock in every size within a week and looks picked-over immediately.
When does going deeper make sense?
When demand is predictable and the item is a repeat or a core line. Newness and fashion risk argue for breadth and shallow depth so the losses on any single miss are small.
Does this include reorders?
No — this plans the initial buy. Keeping a portion of the budget uncommitted for in-season reorders on what actually sells is usually worth more than committing all of it up front.