Combine Shipping Rates
If there are multiple vendors with their own shipping rates, Garnet Marketplace adds up one rate per vendor. Which rates it offers depends on whether the rates come with a delivery date.
Rates with a delivery date
Live rates come with a delivery date, and so do flat rates when the vendor sets a delivery time. As soon as one rate in the cart has a delivery date, Garnet Marketplace displays at most two rates:
- the sum of the cheapest rate,
- 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. When one of the rates has no delivery date, the combined rate shows none either.
A rate without a delivery date counts as the slowest when picking the fastest rate.
Rates without a delivery date
When no rate in the cart has a delivery date, for instance flat rates without a delivery time, there is no fastest rate to pick. Instead, Garnet Marketplace combines the rates that share a name: when every vendor in the cart offers Express shipping, the customer sees Express shipping (x2), the sum of each vendor's Express rate. Names match regardless of capital letters.
Example: Vendor A offers Standard shipping ($10) and Express shipping ($15), vendor B offers Standard shipping ($11) and Express shipping ($15):
| Rate shown at checkout | Composition |
|---|---|
| Standard shipping (x2) | $10 + $11 = $21 |
| Express shipping (x2) | $15 + $15 = $30 |
A rate name that one of the vendors does not offer is left out. The sum of the cheapest rates is still shown when it is cheaper than every shared name, so the customer always has the cheapest option.
To make sure vendors' rates combine, restrict shipping method names so every vendor picks from the same list.
Rates coming from the same warehouse
Some marketplaces operate a warehouse where several vendors keep their stock. When the products in an order leave from that same warehouse address, Garnet asks the carrier for one rate covering every package, rather than a separate rate per vendor. The customer then pays what the shipment actually costs.
One parcel goes out, holding the items of several vendors.
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.