The divisor determines dimensional weight. Lower numbers = higher costs.
Average cost per lb based on distance.
Volumetric (DIM) Weight:–
Actual Weight:–
Billable Weight:–
Base Shipping Cost:–
Handling Fee:–
Total Estimated Shipping Rate:–
function calculateShipping() {
// Get Inputs
var length = parseFloat(document.getElementById('pkgLength').value);
var width = parseFloat(document.getElementById('pkgWidth').value);
var height = parseFloat(document.getElementById('pkgHeight').value);
var weight = parseFloat(document.getElementById('actWeight').value);
var divisor = parseFloat(document.getElementById('dimDivisor').value);
var baseRate = parseFloat(document.getElementById('baseRate').value);
var handling = parseFloat(document.getElementById('handlingFee').value);
// Validation
if (isNaN(length) || isNaN(width) || isNaN(height) || isNaN(weight) || isNaN(baseRate)) {
alert("Please enter valid numbers for dimensions, weight, and base rate.");
return;
}
if (isNaN(handling)) {
handling = 0;
}
// 1. Calculate Dimensional Weight
var dimWeightRaw = (length * width * height) / divisor;
var dimWeight = Math.ceil(dimWeightRaw); // Carriers usually round up to next lb
// 2. Determine Billable Weight (Higher of Actual vs DIM)
var actualWeightCeil = Math.ceil(weight); // Carriers round up actual weight too
var billableWeight = Math.max(actualWeightCeil, dimWeight);
// 3. Calculate Costs
var shippingCost = billableWeight * baseRate;
var totalCost = shippingCost + handling;
// Display Results
document.getElementById('resDimWeight').innerHTML = dimWeight + " lbs";
document.getElementById('resActWeight').innerHTML = actualWeightCeil + " lbs";
document.getElementById('resBillableWeight').innerHTML = "" + billableWeight + " lbs";
document.getElementById('resBaseCost').innerHTML = "$" + shippingCost.toFixed(2);
document.getElementById('resHandling').innerHTML = "$" + handling.toFixed(2);
document.getElementById('resTotal').innerHTML = "$" + totalCost.toFixed(2);
document.getElementById('results').style.display = 'block';
}
What Are Shopify Carrier Calculated Shipping Rates?
For e-commerce merchants, shipping is often the most complex variable in the profitability equation. Carrier Calculated Shipping (CCS) is a feature in Shopify that allows your checkout to connect directly with shipping carriers like UPS, FedEx, USPS, and DHL in real-time. Instead of charging a flat rate (e.g., $10 per order), the system calculates the exact cost to ship a specific package weight and size to the customer's specific address.
This calculator simulates the logic used by major carriers to determine these rates, helping you understand how package dimensions and "billable weight" impact the final price your customers see at checkout.
The Math Behind the Rates: Dimensional vs. Actual Weight
One of the biggest sources of confusion for new merchants using Shopify Carrier Calculated Shipping is why a light but large package costs so much to ship. The answer lies in Dimensional (DIM) Weight.
Carriers don't just charge based on how heavy an item is; they also charge based on how much space it takes up in their truck or plane. The formula generally used is:
(Length × Width × Height) ÷ Divisor = DIM Weight
The Divisor varies by carrier:
139: Common for UPS and FedEx daily rates.
166: Often used for retail rates.
194: Sometimes applied for USPS domestic zones.
The carrier compares the Actual Weight of the package against the DIM Weight. Whichever number is higher becomes the Billable Weight.
Example Scenario
You are shipping a pillow. It weighs only 2 lbs, but the box is 18″ x 12″ x 12″.
Actual Weight: 2 lbs
DIM Weight Calculation: (18 x 12 x 12) / 139 = 18.6 lbs (Round up to 19 lbs)
Even though the pillow is light, the carrier will charge you for a 19 lb package. If you don't account for this in your Shopify shipping settings, you might undercharge your customer significantly.
How to Enable Carrier Calculated Shipping on Shopify
This feature is not automatically enabled on all Shopify plans. To get real-time rates at checkout, you typically need one of the following:
Advanced Shopify Plan: Included by default.
Carrier Service API Add-on: Available for an extra monthly fee on lower plans.
Annual Billing: Many merchants on the "Basic" or "Shopify" plan can get this feature added for free if they switch from monthly to annual billing. Contact Shopify support to request this.
Strategies to Reduce Shipping Costs
Once you understand the math behind the rates, you can optimize your packaging:
Reduce Empty Space: Use the smallest box possible. Cutting just 2 inches off a box height can save significant money in DIM weight fees.
Poly Mailers: For non-fragile items (like clothing), poly mailers add almost no dimensions or weight, often resulting in the cheapest actual weight rates.
Accurate Product Weights: Ensure every product in your Shopify admin has an accurate weight entered. If you leave it at 0, the carrier calculation will fail or return a default error rate.
Frequently Asked Questions
Why are my Shopify shipping rates not showing up?
Ensure you have "Carrier Calculated Shipping" enabled on your plan. Also, check that you have defined shipping zones for the destination address and that your products have weights assigned to them in the product editor.
Can I add a markup to the calculated rates?
Yes. In your Shopify Shipping settings, you can add a percentage markup or a flat fee handling charge on top of the carrier rate. This helps cover the cost of boxes, tape, and labor.
Does Shopify include box dimensions in the calculation?
Shopify's default setting calculates rates based on the total weight of the cart and a single "default package" size. For more accurate calculations involving multiple box sizes or complex dimensional logic, you may need third-party apps like Boxify or Intuitive Shipping.