You ordered too many L's again.
Sizo is building a model trained on your shop — not the industry average. The right size ratio, the right opening order, the right total quantity. Engineered for your customers, your fit, your sell-through.
A minute to connect.
A whole season of intelligence.
Connect your store
1-click Shopify install. Read-only. No dev work, no exports. Done in under a minute.
Sizo reads your data
Order history by size, stockout filtering, demand curves — calculated automatically.
Brief your supplier
Review the recommended ratio, export PDF or CSV, send straight to your factory.
Every restock is a bet.
Most brands are losing it.
Brands forfeit up to 20% of monthly profits to poor size distribution.
Fashion produced 2.5–5B excess items in 2023, valued at $70–$140B in unsold inventory.
76% of shoppers say stockouts damage brand perception. 55% won't come back after it happens twice.
Spreadsheet + gut feeling
- · Default to a 1-2-2-1 ratio, every time
- · Stockouts skew the data, you can't see it
- · Trends move, your ratios don't
- · Hours rebuilding the PO sheet by hand
Demand curve + 98% confidence
Your actual ratio, calculated from real sales Stockout periods filtered out automatically 30/60/90-day trend shifts surfaced Export PDF or CSV in one click
Restock intelligence.
The right ratio, every time.
After a product launches, Sizo tracks every sale and return by size. It calculates your real demand curve — say, XS:S:M:L:XL = 1:3:2:1:0.5 — and tells you exactly what to order next. Based on data, not instinct.
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Real demand by size
Stockout periods are filtered out so your ratio reflects what customers wanted, not what was on the shelf.
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Confidence scoring
If a size only moved 12 units, Sizo flags it. You'll know when to trust the number and when to apply judgment.
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Trend shifts over time
30, 60, and 90-day movement, so your restock reflects this season's customer — not last year's.
Three pillars.
One smarter purchase order.
Restock today. Launch and Quantity next. The full picture of what to buy, how much, and in what split.
Don't guess the opening order.
For products that have never sold, Sizo finds comparable items in your catalog — same cut, category, customer — and synthesizes a recommended opening ratio from their real demand curves.
Not just which sizes — how many, total.
Sales velocity, lead time, and sell-through combine into a recommended total quantity. Set a budget or unit target and see which sizes will stock out first, when, and by how much.
We were buying on instinct — same ratio every drop. Sizo showed us our actual curve was nothing like what we assumed. The next order sold through cleaner than anything we've shipped.
A model trained on your shop.
Most tools average across the industry. Sizo learns from the customers actually buying from you — their fit, their size, their patterns. Here's what that looks like in practice.
We don't count what you couldn't sell.
When a size is out of stock, customers can't buy it — but most tools still treat that as "low demand." Sizo finds those gaps in your inventory history and removes them, so your ratio reflects what people actually wanted.
We tell you when we're not sure.
A new product with 30 sales doesn't get the same recommendation as a hero SKU with 3,000. Sizo shows confidence on every number — so you know when to trust it, and when to wait for more data.
We notice when your customers change.
Maybe your audience is shifting toward larger sizes. Maybe a new fit is pulling in a different body type. Sizo compares your last 30/60/90 days to your full history and surfaces the shift — before it shows up as aged stock.
Things founders ask us.
What data does Sizo read?
Order history, line items by SKU and size, inventory snapshots, and returns. All read-only through the official Shopify API. Nothing about your customers personally — we only need the size of what was bought.
How long until I see a recommendation?
Connection takes under a minute. Sizo backfills your full sales history and surfaces ratios for any product with enough volume to score. For most brands that's the same day.
Why invite-only?
We're already working hands-on with a small group of design partners — onboarding them, validating recommendations against real next POs, and tightening the math against their category. Once that loop is consistent, we open the door more broadly.
Shopify only?
Out of the box, yes — Shopify covers the brands we're built for. Our Enterprise plan connects to other systems too: ERPs, custom data warehouses, and direct integrations on request.
What if a product is brand new — no sales history?
That's a known gap. Today, Sizo focuses on restocks where we can measure real demand. Opening orders for new drops is something we're actively working on.
Stop guessing.
Start selling through.
Tell us about your shop. We'll add you to the waitlist.