Inventory how-to

How to switch suppliers without running out

Overlap the old and new supplier for at least one full lead-time cycle of the new supplier.

Short answer: Overlap the old and new supplier for at least one full lead-time cycle of the new supplier. Keep ordering from the old supplier on your normal schedule until the new supplier has a proven lead time and the first shipment is confirmed on hand.

Why switching is risky

A new supplier is an unknown quantity until you have real data. Their quoted lead time may not match reality the first few times. If you cut off the old supplier too early and the new one is late, you run out.

Build a buffer before you cut over

Add extra safety days to the new supplier's lead time for the first one or two orders. Treat the quoted lead time as unproven and pad it. Once you have two or three completed orders with real delivery dates, you can trust the average and tighten the safety days back down.

Keep the old supplier alive longer than feels necessary

Place one last order with the old supplier sized to cover you through the new supplier's first delivery plus your normal safety stock. Do not cancel the old supplier relationship until the new supplier's first shipment is received and counted into stock.

Watch the SKUs with the longest lead times first

If the new supplier ships from a different location or country, lead times can be longer than the old one. Recalculate reorder points per SKU using the new lead time, not the old one, as soon as you know it.

Step by step

  1. List every SKU sourced from the supplier you are leaving.
  2. Get a real quoted lead time and minimum order quantity from the new supplier in writing.
  3. Place a final, slightly larger order with the old supplier to cover the transition window.
  4. Place a first trial order with the new supplier and track the actual delivery date against the quote.
  5. Update each SKU's lead time and safety days to match the new supplier once confirmed.
  6. Do not remove the old supplier as an option in your system until the new supplier's stock is received and counted.
  7. Recheck reorder points after the first two or three orders from the new supplier.

Worked example

A store sells a candle at 6 units a day. The old supplier has a 10-day lead time and 4 safety days, so reorder point was 6 x 14 = 84 units. The new supplier quotes 18 days but it is unproven, so safety days are padded to 10 for the first order, giving a reorder point of 6 x 28 = 168 units. The store places a final order with the old supplier sized to last 28 days, and only drops the old supplier once the new one delivers on time twice.

How SteadyShelf helps

SteadyShelf lets you update a SKU's supplier, lead time and safety days at any point, and it recalculates the order-by date and suggested quantity from the new numbers right away. It does not manage the supplier relationship or negotiate terms for you, and it will not know the new supplier's real lead time until you enter it or until a few orders complete.

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

SteadyShelf is launching on the Shopify App Store. Join early access to get the install link first.

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FAQ

Should I switch all SKUs to the new supplier at once?

No. Switch a small batch of lower-risk SKUs first to confirm the new supplier's lead time and quality, then move the rest once you trust the numbers.

What if the new supplier has a higher minimum order quantity?

Recalculate your order quantity against the new minimum and case pack size. If the minimum is much higher than your usual order, check it against your days of cover so you are not left holding excess stock.

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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