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EngineeringProduct·May 2, 2026· 6 min read

How we decide which supplier ships which item

A quick read on the cart-split optimizer — what it considers, what it ignores, and why a single-supplier order isn’t always cheaper.

By Eng @ shopdental

When you check out, your cart almost never goes out as one order. We split it across the cheapest combination of suppliers — but “cheapest” takes more than the per-line price into account.

What the optimizer balances

  • Per-line offer price across every supplier that stocks the item
  • Supplier-specific shipping thresholds (free over $X, flat $Y under)
  • Carrier ETA — we won’t move a stat-needed item to a slower supplier just to save 80 cents
  • In-stock vs. backordered status at the moment of checkout

Why splitting often beats single-supplier

When two of three items in your cart are cheapest at supplier A but the third is significantly cheaper at supplier B and would push A’s sub-cart below the free-shipping threshold anyway, splitting wins. The optimizer surfaces the savings on the cart screen so you can sanity-check the call.

Override is one click

If you’d rather keep an order with one supplier — for invoicing, or because of a contract — toggle “Single supplier” on the cart and we’ll re-route everything through your preferred vendor.