Inventory how-to

How to forecast demand for slow moving products

For slow movers, use a longer sales window and round numbers, not daily averages.

Short answer: For slow movers, use a longer sales window and round numbers, not daily averages. Look at units sold over 90 to 180 days instead of 28 days, then divide to get a weekly or monthly rate, because a short window often shows zero or one sale and gives you a false signal.

Why short windows fail for slow movers

A product that sells 10 units a day gives you a solid signal in 28 days. A product that sells 10 units a year gives you almost nothing in 28 days, you might see zero sales or one random spike. Short windows turn slow movers into guesswork.

Use a longer lookback period

Pull sales for the last 6 to 12 months for each slow SKU. Add up total units sold and divide by the number of days in that period to get a daily rate, then multiply by 7 or 30 for a weekly or monthly rate. This smooths out random gaps and spikes.

Treat zero sales periods as data, not noise

If a SKU had zero sales for 60 days then sold 5 units in a week, do not treat that week as the new normal. Keep the longer average unless you have a real reason for the change, like a price drop, a new listing placement, or a seasonal pattern repeating year over year.

Set safety stock by cost and lead time, not by formula alone

For slow, cheap items, it is often fine to hold a bit of extra stock since carrying cost is low and stockouts annoy customers. For slow, expensive items, lean toward ordering smaller quantities more often even if the per-order cost is higher, so you are not tying up cash in stock that moves once every few months.

Step by step

  1. List all SKUs with low sales volume over the past 90 days.
  2. Pull 6 to 12 months of sales history for each one.
  3. Calculate a daily rate: total units sold divided by number of days in the period.
  4. Convert to weekly or monthly rate if that is easier to work with.
  5. Check for seasonal patterns by comparing the same months in prior years, if you have that history.
  6. Set reorder points using the longer-term rate, not the last 28 days.
  7. Review these SKUs less often than fast movers, monthly is usually enough.

Worked example

A store sells a niche accessory and moved 18 units in the last 180 days, with 0 units in some months and 6 in one month due to a gift season. Daily rate is 18 divided by 180, which is 0.1 units per day, or about 3 units per month. Lead time is 30 days and safety days are 15 days, so reorder point is 0.1 x (30 + 15) = 4.5, round up to 5 units. If on hand is 6 and nothing is on order, the store does not reorder yet since 6 is above the reorder point of 5.

How SteadyShelf helps

SteadyShelf's default forecast window is 28 days, which works well for regular movers but is too short for genuinely slow SKUs. Once a SKU has about 13 months of history, SteadyShelf can factor in seasonality, which helps slow movers with yearly patterns, but for very low volume items you may still want to sanity check the suggested order quantity against a longer manual average before approving the purchase order.

$29/month flat, unlimited products and suppliers, 30-day free trial. Run the numbers now with the free reorder point calculator.

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FAQ

What counts as a slow moving product

There is no fixed line, but a common practical marker is a SKU that sells less than one unit a week on average, or one that frequently shows zero sales in a 28-day window. If your standard forecast window keeps showing no clear trend, treat it as slow moving and switch to a longer lookback period.

Should I stop stocking slow movers altogether

Not necessarily. Some slow movers are important for customers even if they rarely sell, like spare parts or niche variants. Decide based on margin and whether customers expect the item to be available, then order small quantities infrequently rather than dropping the SKU outright.

Let SteadyShelf do this math for every SKU

Order-by dates per supplier, seasonal forecasts and draft POs for your Shopify store. $29/month after a 30-day free trial.

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