--- title: "Flat rate shipping boxes for fast delivery" url: "https://www.shipstation.com/en-gb/fulfillment/shipping/flat-rate-shipping-boxes/" type: "page" modified: "2026-07-13T08:11:56-05:00" --- Flat Rate shipping/boxes that stay predictable at every order volume ==================================================================== When you’re choosing shipping and boxes, you want a clear winner fast. In ShipStation, you can manage orders from all your sales channels in one end-to-end platform, compare USPS Flat Rate® packaging against 200+ carrier rates, and print labels in batches—all from one screen. Bring your own carrier accounts or use our discounted options, track every package, and keep your workflow moving with you. [ Start a Free Trial ](https://www.shipstation.com/start-a-free-trial/) [ Contact Us ](https://www.shipstation.com/contact-us/) ![](https://www.shipstation.com/wp-content/uploads/2026/06/flat-rate-shippingboxes-that-stay-predictable-at-every-order-volume-260612-0742.webp) Predictable cost, faster choices, and fewer manual steps for your business -------------------------------------------------------------------------- Flat pricing feels simple. Real shipping decisions aren’t. We help you weigh Flat Rate boxes against weight-based rates, carrier options, and delivery speed, then move straight from order import to label and tracking. ![](https://www.shipstation.com/wp-content/uploads/2026/02/icon-bbd4cfaccc8a.png) ### Know your cost before you pack based on weight and box choice Flat Rate shipping can be the clean answer when weight climbs or destinations are farther away. You choose the Flat Rate box or envelope, and the cost stays tied to that package type. That makes quoting easier, even when orders vary day to day. You can still enter package details to avoid surprises and keep rate results accurate. ![](https://www.shipstation.com/wp-content/uploads/2026/06/icon-ddc9b585ec9a.png) ### Get commercial pricing without doing extra math Retail counter pricing at the post office can differ from commercial pricing. Our platform shows available rates inside your workflow, so you can compare what you’ll actually pay before you print. Connect your existing carrier accounts to keep your negotiated rates, then rate-shop next to other options. Many teams also use discounted USPS rates, with no separate Stamps.com® account required. ![](https://www.shipstation.com/wp-content/uploads/2026/02/icon-5ae890648f70.png) ### Pick the best shipping services automatically, not manually Flat Rate boxes are one option. They’re not always the best. With automation rules, you can guide ShipStation to choose Flat Rate shipping when it fits your items, and switch to other services when it doesn’t. That means less tab-switching, fewer overrides, and faster label creation when order volume spikes. Rated #1 by Industry Leaders ---------------------------- We’ve helped 130,000+ businesses manage their shipping smarter. Let us save your team time and money, too. ![](https://www.shipstation.com/wp-content/uploads/2026/03/Shipping_EasiestSetup_Mid-Market_EaseOfSetup.svg) ![](https://www.shipstation.com/wp-content/uploads/2025/07/SoftwareAdvice2025.png) ![](https://www.shipstation.com/wp-content/uploads/2026/04/Shipping_BestEstimatedROI_Mid-Market_Roi.svg) ![](https://www.shipstation.com/wp-content/uploads/2025/07/CapterraShortlist2025.png) ![](https://www.shipstation.com/wp-content/uploads/2026/03/Shipping_MomentumLeader_Leader.svg) ![](https://www.shipstation.com/wp-content/uploads/2025/09/g2-fall-2025-users-love-us.svg) Google 4.9 rating 67 reviews Capterra 4.6 rating 897 reviews G2 4.3 rating 531 reviews Flat Rate shipping options you can set once and run every day ------------------------------------------------------------- Use USPS flat rate packaging when it makes sense, then compare it against other rates and services in the same workflow. Turn rules into repeatable decisions, print in batches, and keep tracking tied to every order. ### USPS Flat Rate packaging quick reference: Flat Rate box, Flat Rate envelope Flat Rate packaging only shows when you select USPS Priority Mail as your service, so your team doesn’t waste time hunting for the right menu. Once enabled, your package drop-down can include common flat rate boxes and envelopes, like: - Small Flat Rate Box, Medium Flat Rate Box, Large Flat Rate Box - Flat Rate Envelope, Legal Flat Rate Envelope, Padded Flat Rate Envelope That “pick a package type, get a predictable rate” flow is the whole point of USPS Flat Rate, and we keep it right inside the label screen. [Explore USPS Priority Mail Shipping](/fulfillment/shipping/usps-priority-mail/) ![](https://www.shipstation.com/wp-content/uploads/2026/06/usps-flat-rate-packaging-quick-reference-flat-rate-box-flat-rate-envelope-260612-0742.webp) ### Automation rules that pick Flat Rate shipping when it's the best option Flat Rate works great for some shipments and is a bad deal for others, so instead of guessing, you can build automation rules that steer each order toward the best option based on weight, destination, SKU patterns, or order tags. Dense items can default to a medium Flat Rate box, light orders can rate-shop against USPS Ground Advantage®, and far destinations can compare Priority Mail Flat Rate against other carriers. You set the logic once—ShipStation handles the sorting from there. [Add Order Fulfillment Automation](/fulfillment/automation/) ![](https://www.shipstation.com/wp-content/uploads/2026/06/automation-rules-that-pick-flat-rate-shipping-when-its-the-best-option-260612-0742.webp) ### Mail Flat Rate labels fast with Priority Mail Flat Rate batch workflows Flat Rate only saves time if your shipping floor moves. We help you go from paid order to printed label without extra clicks. Batch printing keeps your day tight, even when you’re shipping across multiple channels. Run common tasks in the same flow: - Print labels in bulk, then print packing slips - Generate an end-of-day form when it fits your carrier workflow - Schedule pickups for UPS® or USPS from inside ShipStation Pair that with ShipStation Connect, and your pack station can print to a 4×6 thermal label printer with no driver setup. [Try Automated Label Printing](/fulfillment/shipping/print-labels/) ![](https://www.shipstation.com/wp-content/uploads/2026/06/mail-flat-rate-labels-fast-with-priority-mail-flat-rate-batch-workflows-260612-0742.webp) ### Compare flat pricing options across carriers, including simple rate USPS Flat Rate is one path to predictable cost. Other carriers also offer flat pricing programs, like UPS Simple Rate, along with their own packaging and rules. In ShipStation, you can rate-shop across services without treating Flat Rate like a separate project. You’ll see rates side-by-side, then choose what matches the order: - Fast delivery when the customer paid for speed - Lower shipping costs when margin is tight - A package option that fits the items without wasted space One screen. Clear choices. Less second-guessing. [Try Shipping Cost Calculator](/fulfillment/shipping/shipping-rates-calculator/) ![](https://www.shipstation.com/wp-content/uploads/2026/06/compare-flat-pricing-options-across-carriers-including-simple-rate-260612-0742.webp) ### International shipping with Flat Rate packaging, customs, and tracking data International Flat Rate can work well for certain shipments, but cross-border adds paperwork and compliance. ShipStation handles key label details in the same workflow where you pick your service, including electronic customs declarations when the carrier supports it. As of September 1, 2025, USPS requires a six-digit HS code on customs declarations for each item on international commercial shipments. You can also access services like GlobalPost™, where duties and taxes may be paid by the recipient (DDU) or by you (DDP) for select destinations. Tracking availability varies by service, but labels include a tracking number when the carrier provides one. [Explore International Shipping Software](/fulfillment/shipping/international/) ![](https://www.shipstation.com/wp-content/uploads/2026/06/international-shipping-with-flat-rate-packaging-customs-and-tracking-data-260612-0742.webp) ### Pull orders from ecommerce businesses across Shopify, Amazon, and more Flat rate decisions get messy when orders live in different dashboards. We pull them into one queue so your rules can apply consistently, even when you sell everywhere. Connect Shopify, Amazon, eBay, Etsy, Walmart, WooCommerce, and BigCommerce, then keep fulfillment in one place. That matters for real operations: - Multi-channel businesses that need one packing workflow - Amazon FBA and Amazon FBM sellers who want orders tagged and split by rule - Teams that want tracking pushed back automatically after label purchase You ship faster when your orders aren’t scattered. [Browse Integrations](/partners/) ![](https://www.shipstation.com/wp-content/uploads/2026/06/pull-orders-from-ecommerce-businesses-across-shopify-amazon-and-more-260612-0742.webp) ### Branded tracking that reduces delivery questions The label isn’t the end of the job. Tracking is where customers judge you. We let you replace carrier-branded tracking with your own branded tracking page and proactive notifications, so fewer people ask where their package is. Use it for: - “Shipped” and “delivered” updates that match your brand - One tracking link your support team can trust - Clear status for every order, even when you mix flat rate boxes with other shipping services [See Ecommerce Branded Tracking](/fulfillment/shipping/tracking/) ![](https://www.shipstation.com/wp-content/uploads/2026/06/branded-tracking-that-reduces-delivery-questions-260612-0742.webp) USPS flat rate boxes and flat rate shipping FAQs ------------------------------------------------ ##### How much is a USPS Flat Rate box? Pricing depends on the specific flat rate box or envelope you choose, plus whether you’re viewing retail or commercial pricing. In ShipStation, you can see the rate when you select USPS Priority and a flat rate package type. You can also compare that cost against other rates before you print. ##### What is the weight limit for Flat Rate shipping? USPS sets limits and restrictions for Priority Mail flat rate packaging, and those rules can change. In ShipStation, enter the correct package weight and choose the matching flat rate package type so rating stays accurate. If you’re unsure, review current USPS guidelines before shipping. ##### When is Flat Rate cheaper than standard Priority Mail or Ground Advantage™? Flat rate often works best for heavy, dense items, especially when the shipment travels farther. It can cost more for light items or compact orders going nearby. The fastest way to know is to rate-shop: compare flat rate shipping against weight-based Priority Mail, USPS Ground Advantage, and other carrier options right on the order. ##### How do I order USPS Flat Rate boxes from the post office? Many merchants pick up flat rate boxes at the post office, and many also order supplies online through USPS.com. Either way, you’ll still want your shipping software ready to match the right flat rate box to the label. Once you’ve got packaging on hand, your team can ship without last-minute supply runs. ##### Does Flat Rate shipping include tracking and insurance? When the carrier supports it, labels you create include a tracking number you can use for tracking updates. Coverage and included protection vary by service, and tracking may not be available for every shipping service. You can also add insurance options in ShipStation, and additional fees may apply depending on what you select. ##### Can I use Flat Rate boxes with UPS or FedEx? Flat rate boxes are a USPS packaging type tied to USPS flat rate services. If you’re shipping with UPS or FedEx, use packaging and rules that match that carrier’s service requirements. In ShipStation, you can still compare USPS flat rate against other carriers’ flat pricing options so you’re choosing based on the shipment, not habit. ##### How do I turn on USPS Priority Mail flat rate boxes and envelopes in ShipStation? Enable the flat rate package types in your settings first, then select them on an order. In ShipStation, go to Account Settings, then Shipping, then Packages, and choose USPS under Manage package types. Turn on the flat rate boxes and envelopes you want, save, then select USPS Priority as your service and pick the flat rate package type from the Package menu. For the exact steps, see the help article on our help center at https://help.shipstation.com/hc/en-us/articles/4418051154843-How-do-I-use-USPS-Priority-Flat-Rate