> ## Documentation Index
> Fetch the complete documentation index at: https://docs.launchmystore.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Rate Engine

> Advanced shipping rates — rules, conditions, box packing and rate blending

# Rate Engine

Rules-based shipping rates for stores whose shipping is more than "one price
per country". Comparable to ShipperHQ / Intuitive Shipping / Calcurates.

## For merchants

* **Rule builder** (Settings → Shipping → Rate Engine): ordered rules, each
  with conditions and one or more rates. Conditions cover destination country,
  state/province, postcode prefix / range / list, PO-Box detection, cart total,
  item count, weight, product tags, vendors and SKUs, and customer tags.
* **Rate types**: flat, per-weight bands, per-price bands, per-item, and
  free-shipping thresholds; surcharges (handling, oversize, fragile) and
  discounts; rename / hide / reorder the store's native zones.
* **Packing**: define your box catalogue (inner dimensions, max weight, cost);
  the engine packs the cart (first-fit decreasing) and prices per box, with
  volumetric weight where the carrier bills that way.
* **Blending**: when several rules match, take the cheapest, the most
  expensive, the first match, or show all.
* **Live preview**: test any cart + destination against your rules before
  shoppers see them.

## For developers

| Contract | Used for |
| - | - |
| [`shipping_rate` function](https://docs.launchmystore.io/functions/shipping-rate) | Emits the computed rates; receives line weights/dimensions, destination, origin and cart attributes |
| [`delivery_customization` function](https://docs.launchmystore.io/functions/delivery-customization) | Hides, renames and reorders both native zones and the app's own rates |
| [Admin block](https://docs.launchmystore.io/extensions/admin-blocks.md) at `admin.shipping-settings.block.render` | The rule builder and box catalogue |
| [Metafields](https://docs.launchmystore.io/api-reference/metafields/list.md) (`shop`) | Stores the rules and boxes |

Rates are returned in **minor units** (cents / paise). Every function call is
signed by the platform with the installation's access token — verify it before
pricing anything (see [Functions overview](https://docs.launchmystore.io/functions/overview.md)).


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