A new product has no sales history, so the usual formulas have nothing to work with. Order too much and you fund a pile of unsold stock. Order too little and you sell out just as interest builds. This guide shows how to estimate a first order, limit the risk, and switch to real data quickly.
Estimate demand without history
You need a starting figure for daily sales. Build it from more than one source, then use the cautious end of the range.
- A similar product: The early weeks of a comparable item in your own store
- Your traffic: Expected visits to the page × your store's usual conversion rate
- Pre-orders or a waitlist: Real signals of intent before you commit
- Your launch plan: Email list size, ad budget and any promotion
Treat each one as a rough estimate. Where two sources agree, you can lean on them more.
The first-order formula
Decide how many days of sales the first order should cover, then add the time it takes to restock. That way you can reorder once you see real sales, and the next shipment arrives before you run out.
- Expected daily sales: Your estimate from above
- Review period: Days of selling before you decide on a reorder
- Lead time: Days from reorder to stock on the shelf
- First order: Expected daily sales × (review period + lead time), plus a buffer
Work it through
You expect to sell 5 units a day. You want 14 days of sales before deciding on a reorder, and your supplier's lead time is 21 days.
| Step | Result |
|---|---|
| 5 a day × (14 + 21) days | 175 units |
| Add a 20% buffer | 210 units |
The buffer here is an example. Use a larger one if your estimate is shaky or the supplier is new to you.
Check it against the constraints
The formula gives you a target. Your supplier and your bank balance decide what is possible.
- Minimum order quantity: If the minimum is far above your target, negotiate or reconsider
- Price breaks: A lower unit cost is no saving if the extra units do not sell
- Cash: Work out how long the order ties up money before it pays back
- Shelf life: Perishable or dated products need a smaller first order
- Variants: Split the quantity by size or color using a similar product's mix, and go light on the extremes
Switch to real data
Once the product has been selling for a couple of weeks, replace the estimate with actual sales velocity. Then set a proper reorder point and safety stock, and keep checking as the launch spike settles.
- Week one: Often inflated by launch promotion
- After that: A truer daily rate
- Next: Calculate a reorder point and safety stock
Doing this at scale
Once a product has orders behind it, StockSense forecasts per-SKU demand from your order history using velocity, trend, seasonality and lead-time-aware safety stock. It recommends a reorder point, quantity and date, and drafts purchase orders grouped by supplier. See StockSense.