> For the complete documentation index, see [llms.txt](https://docs.pakk.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pakk.io/account-setup/shipping-methods/shipping-calculations.md). # Shipping Calculations Understand the various algorithms available for calculation of shipping charges The simplest possible option is a `fixed` shipping charge - for example, 5 EURO. Whilst this **is** available in Pakk, it's not that useful normally. In most cases, we'll want to vary the charge based on some element of the cart/order. Pakk allows you to calculate shipping based on: * Total order weight * Number of items in order * Number of units in order * Order subtotal before tax * Order subtotal after tax Once you've decided on what axis you want to base this shipping method, you need to decide exactly how to perform the calculation. #### Per-Item Delivery Surcharges **Per-item delivery surcharges** are set at product level. If a product has a delivery surcharge of £5 set, then an extra £5 (per unit) will be factored into the total shipping cost, irrespective of the Shipping Method chosen. However, if, for a particular Shipping Method, you would like to NOT include per-item charges (for example, for a 'Collection'-type Shipping Method), you can `exclude per-item charges`. #### Free Shipping Irrespective of which calculation type you choose, you can set a threshold for free shipping. This threshold will be activated as soon as the order value (including discounts, not including payment method surcharges) is **equal to or over the threshold**. By default, the threshold is the **inc. VAT** total, which is normally the right setting for retail sites. Trade sites might want to use the **ex. VAT** order total as the threshold, which can be achieved by setting `free over is ex` to `true`. If you decide to offer free shipping, you'll also need to decide whether to `free includes per item charges`. If you set this option to `true`, then all item delivery surcharges will also be waived once the condition for free delivery is met. If this is set to `false`, then once the condition for free delivery is met, the main delivery charge will be free, but individual item surcharges will still stand. #### Linear The amount charged will either go up or down depending on the value of the axis (weight/order value etc). There are quite a few sub-options: * `base amount`, can be thought of the starting amount from where the rest of the calculation takes over. * `over` is the threshold for the linear calculation to kick in (grams, cents or units). * `unit amount`, how much **extra** to charge per increment of the axis once past the `over` threshold. If you set this to a negative value, then the charge will *go down* as the increment *goes up* * `step size`, the size of the increment you want to charge for (grams, cents or units); e.g. every additional 100 grams. **Example 1** We want to set up a shipping method which will cost 5 GBP for orders up to 20kg. After 20Kg we want to charge 0.20 GBP per Kg. *Note that we specify weights here in grams*: * axis = total order weight * `base amount` = 5.00 * `over` = 20,000 (20Kg => 20,000 grams) * `unit amount` = 0.20 * `step size` = 1000 (1000 grams => 1 Kg) **Example 2** We want to charge a basic rate of 10 GBP, but we want this to start going down once a customer spends over 200 GBP including VAT. In fact, we'd like it to decrease by 1 GBP for every 100 GBP spent. At 1000 GBP we want shipping to be free: * axis = order subtotal after tax * `base amount` = 10.00 * `over` = 1000 (10 GBP => 1000 pence) * `unit amount` = -1.00 * `step size` = 10,000 (10,000 pence => 100 GBP) * `free over` = 100.00 * `free over is ex` = `false` (to use the \*\*inc VAT cart value) #### Band-based The amount charged will be determined by a list of band thresholds and a list of band amounts. * `band limits` is a list of where the cutoff for each band falls, specified in units/cents/grams (depending on whether you are using units, price or weight as the axis) * `band amounts` is a list of costs associated with each corresponding band threshold **Example 1** Charge in bands of 1 kg. Each band is obviously more expensive, but the difference gets smaller as the weight increases: * `band limits`: \[ 1000, 2000, 3000, 4000, 5000] * `band amounts`: \[ 10, 19, 27, 35, 40] --- # Agent Instructions This documentation is published with GitBook. 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