Inventory how-to

How to manage multiple suppliers for the same product

Pick a primary supplier for each SKU and keep secondary suppliers as backup records with their own lead time and cost.

Short answer: Pick a primary supplier for each SKU and keep secondary suppliers as backup records with their own lead time and cost. Split purchase orders by supplier, not by product, and let each supplier's lead time drive its own order-by date.

Why this gets messy

When one SKU has two or three suppliers, the usual problem is that lead times and minimums differ, so the "right" time to order is not the same for each one. If you treat them as interchangeable, you end up ordering too early from the slow supplier or too late from the fast one.

Set a primary and a backup

For each SKU, decide which supplier is primary. This is the one you reorder from by default. Keep the backup supplier's lead time, case pack size, and minimum order quantity on file so you can switch fast if the primary is out of stock or delayed, without having to chase that information down mid-crisis.

Split stock and orders by supplier, not by product

If you are actively buying the same SKU from two suppliers at once, treat them as two separate supply lines. Track what is on order with each one separately, because lead time and safety days are a property of the supplier relationship, not just the product. A purchase order should only ever go to one supplier at a time.

When to switch or dual-source

Dual-source only when it solves a real problem, such as one supplier being unreliable or a minimum order quantity being too high for your volume. Dual-sourcing adds admin work, so do not do it for SKUs that sell slowly or have no supply risk.

Step by step

  1. List every SKU that has more than one supplier and mark one as primary.
  2. Record lead time, safety days, case pack, and minimum order quantity for each supplier separately.
  3. Reorder from the primary supplier by default using its own order-by date.
  4. If the primary is delayed or out of stock, switch the SKU's active supplier and recalculate the order-by date using the backup's lead time.
  5. Keep purchase orders supplier-specific, never mix two suppliers on one order.
  6. Review every few months whether dual-sourcing is still worth the extra admin for each SKU.

Worked example

Say you sell a candle that you can buy from Supplier A (14-day lead time, case pack of 24, minimum 48 units) or Supplier B (30-day lead time, case pack of 12, minimum 24 units) as backup. You sell 4 candles a day and use 5 safety days. With Supplier A, reorder point is 4 x (14 + 5) = 76 units. If Supplier A has a delay and you switch to Supplier B, reorder point becomes 4 x (30 + 5) = 140 units, so you need to order much earlier and in a bigger batch to cover the longer lead time.

How SteadyShelf helps

SteadyShelf assigns one supplier with its own lead time and safety days per SKU, and calculates the order-by date and quantity from that. It does not manage two active suppliers for the same SKU at once, so if you dual-source, you need to manually update which supplier is assigned to the SKU when you switch, and the quantity suggestion will use whichever supplier is currently set.

$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

Can SteadyShelf split one purchase order across two suppliers for the same SKU?

No. Each purchase order in SteadyShelf is drafted for one supplier. If you want to buy a SKU from two suppliers at the same time, you need to create two separate orders and track them separately.

What happens to the order-by date if I change a SKU's assigned supplier?

SteadyShelf recalculates the order-by date using the new supplier's lead time and safety days as soon as you update the assignment, so switching suppliers for a SKU will shift its suggested order timing and quantity accordingly.

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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