Shopify inventory forecasting: demand basics for small stores

Checked against the live sources below on 27 October 2026.

Inventory forecasting means estimating how many units you will sell before your next delivery lands. For most small Shopify stores, recent sales per day multiplied by your supplier’s lead time is enough to start. Check how fast your stock turns with the free inventory turnover calculator.

The simplest forecast that works

1. Average daily sales. Total units sold over the last 30 to 60 days, divided by the days. Leave out days the product was out of stock, since sales stop when stock does.
2. Days of stock. Units on hand divided by daily sales.
3. Reorder-by date. Today plus days of stock, minus your supplier’s lead time, minus a safety buffer.

With made-up numbers: 400 units on hand and 12 sold a day is about 33 days of stock. With a 14-day lead time and a 5-day buffer, order in roughly two weeks.

Two adjustments make this more honest. Strip out one-off spikes, such as a launch week or a big promotion, so they do not inflate the rate. And when a product was unavailable for part of the window, use only the days it could be bought, or you will understate demand and run out again.

Why recent history beats a long average

A year-long average hides launches, seasons and promotions. A short window reacts faster, but a single viral day can distort it. A common compromise is to look at a recent window, then compare it to the same period last year if you have it, and adjust for anything you know is coming.

Turnover is a check, not a forecast

Shopify defines inventory turnover as cost of goods sold divided by average inventory, and cites a retail benchmark of 10.86 turns, while noting that a good ratio depends on what you sell and to whom. Use the inventory turnover calculator to see where you stand. A low ratio means cash is sitting on shelves; a very high one can mean you run out too often.

With invented numbers: if the cost of the goods you sold in a year is $60,000 and your average inventory is $10,000, you turned stock 6 times, or about every 61 days (365 divided by 6). Compare that with your own history first, and with category averages only if you can find one for what you sell.

Where Restockly fits

Restockly is a free app that does the first three steps for you. Per its listing, it reads your sales history and current stock, sorts every product into one of four tiles (Order now, Order soon, Stocked, No sales) from a live 60-day sales scan, and shows days of stock and a reorder-by date on every row. Its reorder list is grouped by vendor, with suggested quantities you can edit and copy into an email or spreadsheet.

Frequently asked questions

How this page was researched

Read on 27 October 2026. The method is general practice with illustrative numbers; the turnover definition and benchmark come from Shopify’s article; Restockly’s features come from its live listing.

• Shopify: Inventory Turnover Ratio — turnover = cost of goods sold divided by average inventory; Shopify cites a retail benchmark of 10.86 and says a good ratio depends on what you sell and to whom
• Restockly on the Shopify App Store — free; reads your sales history and current stock; four tiles (Order now, Order soon, Stocked, No sales); a live 60-day sales scan with days-of-stock and a reorder-by date on every row; a vendor-grouped reorder list with editable suggested quantities you can copy into an email or spreadsheet
• Wikipedia: Safety stock — the reorder point is the inventory level that triggers an order; lead time is the delay before renewed availability; a higher service level needs more safety stock

Related: Restockly · How much to reorder · Inventory turnover calculator