What a good forecast for a Shopify store needs
- Demand, not just sales. A product that sold out for ten days didn’t have low demand for those ten days. Counting sold-out days as zero makes your best sellers look weaker and leads to ordering too little of exactly what sells.
- The variant level. Forecasting a style as a whole hides the sizes or colours that run out first. The order you place is per variant, so the forecast should be too.
- Each location separately. Shops and the online store sell differently. One forecast for all of them sends stock to the wrong place.
- Returns. Units that come back weren’t really sold.
- The calendar. Seasons, holidays and drops change demand, and your supplier’s lead time decides when the order must leave.
How Sizo forecasts
- It trains a model on your shop. Sizo reads your order history, line items by variant, stock levels by location and returns, read-only through Shopify’s official API.
- It forecasts demand per variant and location, counting only the days each one was actually in stock.
- It recommends the order: how much in total, the split by size or variant, and where each unit should go. You get a conservative, regular and aggressive option, checked against your supplier’s minimum order and lead time.
- It explains itself. Every recommendation comes with the reasoning behind it, and you can ask about your shop in plain English.
- You stay in control. Sizo drafts the order; you review it and send it yourself.
Shopify’s built-in reports vs. a forecasting model
| Shopify reports | Sizo | |
|---|---|---|
| Units sold per variant | Yes | Yes |
| Sold-out days removed from demand | No | Yes |
| Forecast of future demand | No | Yes, per variant and location |
| Recommended order quantity and size split | No | Yes, three options |
| Where each unit should go | No | Yes |
| Reasoning you can read | — | Yes |
Comparing tools?
See Sizo vs Prediko, Sizo vs Inventory Planner by Sage, or, if you used Stocky, what to do now that it has retired.
Want to see the size side of this by hand first? The size curve calculator shows how sold-out days change an order, and which sizes really sell best walks through it step by step.