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

# Setting Up Order-Based Rates

> Walk through the 3-step setup wizard to calculate order-based rates for your Shopify store

## Before You Start

Make sure you have:

* A **connected Shopify store** ([Connect Shopify](/getting-started/shopify))
* **Products imported** from your store (products import automatically once Shopify is connected)
* **Product weights set in Shopify** for every product (required for rate calculations)

Navigate to the **Shipping Setup** page from your dashboard. If this is your first time, click **Start Setup** to begin.

***

## Step 1: Add Parcel Sizes

Enter every box size you use to ship orders. For each parcel, provide:

* **Name** - a recognizable label (e.g., "Small Box", "12x9x4 Mailer")
* **Dimensions** - Length x Width x Height in inches

<Tip>
  Measure the **exterior** dimensions of your boxes. Carriers rate based on outside measurements.
</Tip>

Click **Next** to continue. SimpliSent will automatically create [shipping categories](/compliance/shipping-terms#shipping-category) from your parcels.

***

## Step 2: Categorize Products

Use the **drag-and-drop** interface to assign your Shopify products to parcel categories.

* **Left panel** - unassigned products (from Shopify), grouped by weight
* **Right panel** - drop zones for each parcel category

Drag each product into the smallest parcel it can ship in.

### Combo-Only Parcels

If a parcel size is only used when shipping multiple items together (never for a single product), check the **[Combo only](/compliance/shipping-terms#combo-only-parcel)** box on that category.

<Warning>
  Every product must be assigned to a category. Unassigned products won't have accurate rates at checkout.
</Warning>

***

## Step 3: Set Category Limits

For each category, set the **Max Items** - the maximum number of products that fit in that parcel size. This controls bin-packing at checkout when a customer orders multiple items.

| Category     | Parcel        | Max Items |
| ------------ | ------------- | --------- |
| Small Items  | 6x4x3 Box     | 3         |
| Medium Items | 12x9x4 Mailer | 2         |
| Large Items  | 18x14x8 Box   | 1         |

***

## Calculate Rates

After completing all three steps, click **Calculate Rates**. SimpliSent will:

1. Discover USPS zones for every US destination from your origin ZIP
2. Calculate the exact USPS cost for every parcel-zone-weight combination
3. Save all calculated rates for syncing to Shopify

You'll see a progress screen with an estimated time remaining. Calculation typically takes a few minutes depending on how many parcel sizes you've defined.

***

## What's Next

Once complete, review your rates and sync them to Shopify.

<Card title="Add Rates to Shopify" icon="store" href="/shipping-rates/adding-rates-to-shopify">
  Push your calculated rates to your Shopify checkout.
</Card>