Estimating the number of parcels
The number of parcels can affect which carriers are selectable. For example, some carriers will not allow more than 30 parcels to be placed on a single order. However, the number of parcels can also have a direct cost to the retailer. Therefore it could be important to calculate an estimate of the number of parcels that will be needed to ship the order.
It will be dependent on the items, of course. If you know the rough sizes of the items, and you know the sizes of the parcels that the retailer uses, you can estimate the number of parcels. Even with the precise dimensions of both, it is only ever an estimate at this stage. To keep things simple, it’s probably worthwhile using an “average number of items per parcel” as a basis.
Total weight of consignment
Similar to the number of parcels, the total weight can also affect the retailer’s costs and the available carriers. In the rare event that you actually know the weights of the items, you can work out the total weight. However, it is also just an estimate – packing materials (such as padding) and the boxes themselves) also affect the total shipping weight.
Where the weights are completely unknown, you can supply the “average total consignment weight” to all orders. If you are aware of particularly large products (such as a washing machine) you can add suitably large numbers to it.
Can’t estimate anything
Sometimes, it’s just not possible to estimate weights, dimensions or the number of parcels. In this case, reverting to the defaults is about as good as you can do. The actual costs to the retailer will be wrong, as might be the actual carrier selection. However, as you’ve not estimated the postcode, the availability of the classes of service (or “service groups”, such as “Next day”, “Evening” etc.) will usually be accurate enough.
The charges associated with services are obtained from MetaPack’s Delivery Manager. They are configured by the retailer and can change from time to time. Often, they will be based more on the class of service, rather than the actual cost the carrier charges the retailer. For example, the retailer may choose to offer free delivery for economy services, and a flat rate for Saturday services.
Which shipping location?
With larger retailers, orders might be fulfilled from multiple shipping locations. You can either split the order into different parts (one part for each shipping location), or choose one of them. Another alternative is to have an entirely different, logical shipping location configured that is only used by the delivery options system.
Which delivery address?
If you’re presenting options before the customer has entered their required delivery address, you can use a default postcode. It’s best to choose a typically small-town postcode, rather than one in a large city or in the middle of the countryside. At this point, it’s only an estimate after all.
If you provide both "lat/long" and "postcode" for recipient, "lat/long" will take precedence to find delivery options.