Combine Shipping Rates

If there are multiple vendors with their own shipping rates, Garnet Marketplace will display at most two rates:

1. the sum of the cheapest rate,
2. the sum of the fastest rate.

Here is the combined rate of a flat rate from the first vendor and the live rates from the second vendor.

Unfortunately, Shopify does not allow the customer to select one shipping per items (link) so we have to aggregate the rates.

Combine rates ETA is computed by taking the maximum of both rates. If the first rate has a delivery window of 1 to 3 days, and the second one 2 to 5 days, then the combine rate will be 3 to 5 days.

Local Pickup in combined rates

When some vendors offer Local Pickup, it is handled separately from regular shipping rates. Local Pickup is never mixed into the cheapest/fastest calculation — instead, it generates its own set of combined rates.

Example: Vendors A (Standard, Express, Local Pickup) and B (Standard, Express):

Rate shown at checkout	Composition
Standard (x2)	cheapest(A) + cheapest(B)
Express (x2)	fastest(A) + fastest(B)
Local Pickup + Standard	A Local Pickup + cheapest(B)
Local Pickup + Express	A Local Pickup + fastest(B)

If all vendors offer Local Pickup, a single Local Pickup (xN) row is shown instead of hybrid rates.

Local Pickup rates always appear last in the list, so standard shipping remains the default option.

Testing

Use the shipping rate tester to verify how rates from multiple vendors are combined at checkout.