Inventory how-to

How to forecast demand for a new variant of an existing product

A new variant has no sales history, so you cannot forecast it from its own data.

Short answer: A new variant has no sales history, so you cannot forecast it from its own data. Instead, borrow the demand pattern from a similar existing variant or the product's overall average, then adjust once real sales start coming in.

Start with a proxy, not a guess

Pick the closest existing variant as your proxy. If you are launching a new color or size of a shirt, use the average daily sales of the other colors or sizes as your starting point. If the new variant is a genuinely new flavor or style with no close match, use the product's total sales divided by the number of variants you plan to stock, then weight it based on what you know about demand (a core size like Medium usually outsells an XS or XXL).

Adjust for known differences

If you have reason to think the new variant will sell faster or slower than the proxy, apply a simple multiplier. For example, if past launches of a new color typically do about 70% of the volume of the best-selling color, multiply that color's daily sales by 0.7. Write down your assumption so you can check it against real results later.

Order light and re-check early

Because this first number is a guess dressed up as a forecast, order a smaller first batch than the formula suggests, or lean toward the supplier's minimum order quantity rather than a large buffer. Set a reminder to look at actual sales after two to three weeks. As soon as you have a few weeks of real sales, switch from the proxy estimate to the variant's own numbers.

Rebuild the forecast once real data exists

Step by step

  1. List the variants most similar to the new one and pull their recent daily sales.
  2. Calculate an average daily sales figure from that proxy group.
  3. Apply a multiplier if you expect the new variant to under- or over-perform the proxy.
  4. Use that adjusted daily sales number in your normal reorder point and order quantity formulas.
  5. Order close to the supplier's minimum or case pack size rather than a large first run.
  6. Track actual sales from day one and compare them to your proxy estimate weekly.
  7. Once you have a real sales history for the variant, drop the proxy and forecast from its own numbers.

Worked example

Say you sell a hoodie in Black, Grey and Navy, each averaging 2.0 units/day, and you are adding a new Olive variant. You estimate Olive will sell at about 70% of an average color, so 2.0 x 0.7 = 1.4 units/day. Lead time is 20 days and you want 10 days of safety stock, so reorder point = 1.4 x (20 + 10) = 42 units. For the first order you decide to cover 30 days instead of the usual 40, with zero on hand or on order: order qty = 1.4 x (20 + 30) - 0 = 70 units, which you round to the supplier's case pack of 72.

How SteadyShelf helps

SteadyShelf forecasts from a variant's own 28-day sales window, so a brand-new variant with zero history will not get a meaningful suggested quantity at first. You need to set the first order manually using a proxy variant as described above; once the new variant has several weeks of real sales in Shopify, SteadyShelf will pick it up and forecast it like any other SKU.

$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 if the new variant is part of a completely new product line with nothing similar to compare it to?

Use your gut estimate based on market knowledge, order the smallest quantity your supplier allows, and treat the first few weeks purely as data collection. Resist ordering a large batch until you have real sales to confirm demand.

How long should I wait before trusting the variant's own sales data instead of the proxy?

Four to six weeks of steady sales is usually enough to replace a proxy estimate, though if the product sells very slowly you may need longer to get a reliable daily average.

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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