Frequently Asked Questions

PackOS is two products. PackOS Checkout calculates accurate shipping rates at your Shopify checkout (WooCommerce and other platforms coming soon). PackOS Labels is a label platform for any store — buy labels, manage orders, and see what each shipment cost. Run either alone, or both, in which case the order carries the checkout rate and the label cost together and PackOS calculates the margin.

PackOS uses a bin-packing algorithm to determine the optimal box configuration for each order based on item dimensions. It then fetches real-time rates from USPS, UPS, and FedEx via EasyPost and returns them to the Shopify checkout.Learn more about the shipping rate calculator →

Shipping margin is the difference between what a customer paid for shipping and what the label actually cost. PackOS Checkout records the first figure and PackOS Labels records the second, and because both write to the same order the difference is calculated for you. A tool that only buys labels was never present at the checkout, so it has no record of what the customer paid.

PackOS Checkout is the Shopify app that provides accurate shipping rates at checkout. PackOS Labels is the label platform for any store — buy labels, manage orders, and see margin per shipment. They work alone or together.

PackOS Checkout rate-shops USPS, UPS, and FedEx at checkout. PackOS Labels buys labels from USPS, UPS, FedEx, DHL Express, DHL eCommerce, and Canada Post.

The PackOS wallet is a prepaid service credit balance. Merchants add funds by card from the dashboard. When a label is purchased, the cost is deducted from the balance. Credits are non-transferable and redeemable only for shipping labels.Learn more about label purchasing →

PackOS is present at checkout as well as at the label, so both figures land on the same order. Check ShipStation’s own documentation for what it covers.

PackOS is two products in one platform: PackOS Checkout quotes the rate at your Shopify checkout after picking the real box, and PackOS Labels buys the label, so both figures land on the same order. Shippo publishes what it covers on its own site. PackOS provides both checkout rate calculation and label purchasing in one platform, so the checkout price and the label cost land on the same order.

Bin packing is an algorithm that determines the optimal arrangement of items into boxes. For shipping, it calculates which box sizes minimize wasted space and dimensional weight, producing accurate weight and size inputs for carrier rate calculations.

PackOS Checkout has a 14-day free trial, and it applies to the plan you choose. PackOS Labels needs no trial: it is free, always.See all pricing plans →

Search for PackOS in the Shopify App Store and click Add App. The installation process takes approximately five minutes. PackOS automatically registers as a carrier service and begins providing rates at your next checkout.

PackOS Labels imports WooCommerce orders via webhook so you can buy labels for them. PackOS Checkout rates for WooCommerce and other platforms are coming soon.