Main site

Built-in Modules > FedEx Class

FedEx Class

Important: This plugin relies on third-party resources. The resources might change or be discontinued without notice. Ensure you test the plugin extensively before production use, implement error handling with a try-catch block, have a backup shipping rate ready, and reach out to our support with detailed descriptions of any unexpected issues.


The FedEx class is specially designed for obtaining real-time shipping rates from FedEx.

Class Definition

class FedEx {
  constructor(origin, destination, currency, order_processing_days) {
    // Class constructor

  async getRates(parcels) {
    // Method to fetch rates


  • origin (Object): Represents the "origin" information from the DATA JSON object used in the calculateShippingRates function.
  • destination (Object): Represents the "destination" information in the same DATA JSON object.
  • currency (String): The desired currency ISO code for calculating shipping rates.
  • order_processing_days (Number): The number of days until the parcels will be ready for pickup.

Usage Example

import { FedEx } from "./modules.js"
const fedex = new FedEx(DATA.origin, DATA.destination, DATA.currency, 3);
const parcels = [
  { length: 15, width: 10, height: 5, metricUnit: "CM", weight: 10, weightUnit: "KG", quantity: 2 },
  // ... additional parcels
const rates = await fedex.getRates(parcels);

This example shows the instantiation of the FedEx class with origin, destination, currency, and order processing days. The getRates method calculates shipping rates for a series of parcels, each defined by their dimensions (in cm or inches), weight (in kg or lbs), and quantity.


  • For metric system, the values for metricUnit and weightUnit should be 'CM' and 'KG', respectively.
  • For imperial system, the values should be 'IN' and 'LB', respectively.

The format of the returned rates is aligned with Shopify's shipping rates.

The rates are based on the information on FedEx website. Check the FedEx delivery service is available for the origin and destination region; unavailable service throws null shipping price.

Sample AI Prompt

I'd like a shipping rate calculator that uses the FedEx rates.
The parcels will be ready for pick up in 3 days.
The dimensions and weight of the parcels are contained in the items metafield namespace object called "parcel". Get the first 15 values in the namespace.
It uses the metric unit system.

Sample AI Output

import { enrichItemDetails, FedEx } from './modules.js';

export async function calculateShippingRates(DATA, env) {
    try {
        // Enriching DATA with additional parcel information
        DATA = await enrichItemDetails(DATA, [{ namespace: "parcel", size: 15 }]);

        // Extracting parcels information from enriched DATA
        const parcels = => ({
            length: item.metafields.parcel.length,
            width: item.metafields.parcel.width,
            height: item.metafields.parcel.height,
            metricUnit: "CM",  // Using metric units
            weight: item.metafields.parcel.weight,
            weightUnit: "KG",  // Weight in kilograms
            quantity: item.quantity

        // Setting up FedEx module with necessary arguments
        const fedex = new FedEx(DATA.origin, DATA.destination, DATA.currency, 3);

        // Fetching rates from FedEx
        const rates = await fedex.getRates(parcels);

        // Returning rates in the expected Shopify format
        return { rates };
    } catch (error) {
        // In case of any error, return a rate with price equals to null and other fields set to empty string
        return {
            rates: [{
                service_name: "",
                service_code: "",
                total_price: null,
                description: "",
                currency: "",
                min_delivery_date: "",
                max_delivery_date: ""