If you only have one open to buy budget and you have to choose, go deep on sizes within fewer brands. A boutique that can put a 30G and a 44DDD on a body in the same afternoon owns a market that nobody else in a thirty mile radius is serving. A boutique carrying nine brands in 34B through 38D is competing with every department store and every website on earth, and losing on price.
That is the answer, but it is not the whole answer, because depth has a real cost and brand breadth has real advantages in cash flow and vendor leverage. The right question is not which strategy is better in the abstract. It is which one your specific open to buy dollars, your fitting room conversion, and your reorder speed can actually support.
Here is how to run the math on your own numbers rather than on someone else's philosophy.
What a deep size range costs in units and dollars
Depth is expensive because size ranges expand multiplicatively. Take one style in one colorway. If you carry bands 30 to 44 and cups A through K, the full grid is enormous, and nobody buys the full grid. But even a serious working range costs real money.
Assume a wholesale cost of $34 per bra and a keystone-plus retail of $78. Assume you carry bands 30 to 40 in even sizes only (six bands) and cups D through H (five cups) for one core style in black and one in nude. That is 6 x 5 x 2 = 60 units, at one unit per size, for a single style.
| Buy | Units | Wholesale cost | Retail value |
|---|---|---|---|
| One core style, 2 colors, 30 sizes each | 60 | $2,040 | $4,680 |
| Same style, doubled in the 8 fastest sizes | 76 | $2,584 | $5,928 |
| Three core styles at that depth | 228 | $7,752 | $17,784 |
Those are illustrative assumptions, not survey figures, so substitute your actual cost and margin. The shape of the result holds regardless: three genuinely deep core styles will absorb the better part of eight thousand wholesale dollars, and a great deal of that inventory sits in edge sizes that turn once or twice a year.
The counterweight is that edge sizes rarely get discounted. A 32H in a good core style sells at full retail in month eleven, because the woman who wears it has nowhere else to go. Depth is slow inventory at full margin. Breadth is faster inventory at markdown risk.
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What a wide brand roster costs in minimums and terms
Brand breadth costs you in a different currency: opening orders, minimums, and the administrative weight of running many vendor relationships.
Most bra vendors selling into independents set an opening order minimum, often in the $1,000 to $2,500 wholesale range, with lower reorder minimums after that. Add nine brands and you have committed nine opening orders before you have sold a single garment. You also inherit nine sets of terms, nine ship windows, nine size charts that do not agree with each other, and nine EDI or portal logins.
The hidden cost is on the sales floor. Every brand you add is a brand your fitters must learn: which one runs a full cup narrow, which one's 34D is closer to a 32DD, which one's straps are set wide. A fitter who knows four brands cold outperforms a fitter who half knows nine.
Breadth does buy you something real. It hedges vendor risk when a brand discontinues your best seller or gets bought, it gives you price tiers so you can serve a $52 customer and a $110 customer, and it gives you newness to photograph without new money in depth.
Fitting room conversion under each model
This is where the argument gets settled, and you can measure it in your own store in a month.
Track two numbers per fitting: did you have her size in at least three garments, and did she buy. Under a deep model, the failure mode is "we had her size but not in a cut she liked." Under a broad model, the failure mode is "we had nine brands and not one of them in a 32G."
The second failure is worse, and not by a small margin. A customer who tries three cuts and buys none will usually come back for the next drop. A customer who is told you do not carry her size at all does not come back, tells other women in her size, and is the exact customer who would have been loyal for a decade.
A rough model with assumed inputs: if a deep range converts 6 of every 10 fittings at an average ticket of $140, that is $840 per ten fittings. If a broad range converts 4 of every 10 at $110 because more of the assortment is entry-price, that is $440. Plug your own conversion and ticket in. If your fitting room log shows the size-out failure happening more than once or twice a week, depth is where your next dollar goes.
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Reorder lead times and how they differ by vendor
Depth only works if you can refill. Before you commit to a core size range, get the reorder lead time in writing from each vendor and put it on one sheet.
- Domestic warehouse, in stock program: often ships in a few business days. This is the vendor you build core depth on.
- Domestic warehouse, seasonal only: once the season sells through, it is gone. Never build a core size range on a seasonal program.
- Import or made to order: lead times measured in months. Fine for fashion, fatal for the 30F you promised a customer on Tuesday.
The practical rule: your core styles, the ones you go deep in, must come from vendors with a genuine in stock program and a fast domestic ship. Everything else is fashion, and fashion gets breadth, not depth.
Also ask whether the vendor will drop ship a single unit to your customer under your store's name. A vendor who will do that lets you say yes to an out of stock size without carrying it, which is depth without the cash.
Which model survives a slow quarter
In a soft quarter, breadth eats you. You are carrying nine vendors' worth of aging fashion in the middle sizes that every competitor also has, and the only lever you have is markdown, which is the one lever that does not fix the problem.
Depth survives better for three reasons. Edge sizes hold full price. Your customer base is specific rather than general, so a woman who needs a 34J does not defer the purchase because the economy softened, she needs a functioning bra. And your cash is tied up in styles that do not date, because a well cut nude full cup is not a seasonal item.
The risk in depth is concentration. If your one core vendor discontinues your bestselling style, you have a hole across thirty sizes at once. Mitigate that by holding depth in two vendors rather than one, and by watching for discontinuation notices in every line sheet.
See how FitRoomLog handles this for lingerie and bra fitting boutiques
How to test one against the other in a single season
You do not have to guess. Run a controlled test over one buying season.
- Pick your split. Take your open to buy for the season and allocate roughly 70 percent to depth in two to three core styles from your fastest reordering vendor, and 30 percent to breadth: two or three new brands at their minimum opening order, in a narrow size band.
- Log every fitting. Record the customer's size, the cuts tried, whether her size was available, and whether she bought. This is the whole experiment. Without it you are guessing at the end.
- Tag the size-out. Every time you cannot serve a size, write down the exact band and cup. Twelve weeks of that list is your next buy, written by your customers.
- Measure at 90 days. Compare sell through percentage, gross margin dollars after markdown, and fitting room conversion for the deep bucket versus the broad bucket.
- Reallocate. Move the next season's dollars toward whichever bucket produced more full price margin per dollar invested, not more revenue.
The reason most boutiques never run this test is that the fitting data lives in fitters' heads and on scrap paper, so at 90 days there is nothing to measure. That is a solvable problem, and it is the cheapest part of the whole exercise.
The decision, and the record that makes it
Depth wins on margin, loyalty and recession resistance. Breadth wins on cash flow, newness and vendor risk. Most healthy independents land near a 70/30 split weighted to depth, but the correct number for your store is written in your own size-out list.
FitRoomLog exists to keep that list: every customer's true size and preferred cut, every fitting where you could not serve her, and a restock alert that tells you the moment her size lands so you can reach out before she has bought elsewhere. Buy from your fitting room record, not from the line sheet.
