Shipping with USPS: Online Merchants’ Holy Grail

If there’s one thing savvy online businesses swear by, it’s shipping with USPS. The U.S. Postal Service is convenient, with service to over 157 million addresses in every state, city, and town in the United States. If small businesses are the backbone of America, then the USPS is the heartbeat, helping online merchants continue to access efficient, reliable shipping at a reasonable cost.

While you’re no doubt familiar with basic USPS services, let’s dive into the full benefits of using USPS for your business’s shipping needs. A few topics we’ll address directly in this article include:

  • The variety of service options and speeds when shipping with USPS
  • The potential cost benefits of shipping with USPS (which is often the cheapest option for shipping within the U.S.)
  • How the ubiquitous nature of USPS makes it a good choice for reaching locations around the country
  • The number of free supplies and services available from USPS
  • How USPS shipping software (including Shippo) can be leveraged to simplify USPS shipping and save businesses money

We’ll also explore the rich American history and legacy of USPS to gain a better understanding of how it got to where it is today. Let’s dive in.

USPS Small Business Offerings

When it comes to shipping, there’s no lack of choices for independent businesses. While each carrier has its own benefits, USPS shipping for small business has been and continues to be a great option for five main reasons:

  • The USPS is often the most cost-effective. In terms of affordability, USPS tends to be the best option for sellers shipping lightweight packages. As an example, an 8-ounce parcel measuring 5 inches in length, by 5 inches in width, by 2 inches in height, being shipped from Manhattan (zip code 10021) to Los Angeles (zip code 90007) would cost just under $4 to ship, using Shippo’s discounted First Class Package Service shipping rates. (Estimate pricing for yourself using our USPS postage calculator.)
  • The USPS is reliable. During the 2022 Peak Season, 93.2 percent of First-Class Mail was delivered on time against the USPS service standard. For more recent reliability data – including the percentage of packages delayed by service level – take a look at Shippo’s Time-in-Transit reporting.
  • The USPS offers delivery six days a week (with no extras fees on Saturdays). Unlike private carriers that charge extra fees for delivering on Saturday, USPS has been delivering Monday through Saturday since 1863—and it doesn’t charge extra for it.
  • The USPS provides free package pickup and supplies. The USPS will pick up your packages straight from your home or business for free. What’s more, if you use Shippo to purchase and print your labels, you can schedule a USPS pickup directly within our web app for free – that’s in addition to accessing the best-possible USPS discounted rates.

USPS Priority Mail Flat Rate Boxes

USPS also offers free shipping supplies for some of its services, including:

    • Priority Mail boxes and envelopes
    • Priority Mail Flat Rate boxes and envelopes
    • Priority Mail Express boxes and envelopes

You can find a full list of free shipping supplies here.

  • The USPS is convenient. Buying USPS postage through Shippo is the ultimate in convenience. Not only can you purchase postage online – taking advantage of better rates than you’ll be able to access at local branches – USPS carriers can pick up and drop off packages directly at your home, office, warehouse, or other location. But if you absolutely must visit an in-person branch, you can visit one of the 31,300+ retail Post Office locations found throughout the U.S. – even in small, rural locations.

USPS Shipping Rates and Service Levels

As with most carriers operating today, USPS offers a wide array of shipping options to meet different needs. Take a look at the USPS shipping rates and delivery times by service level in the table below to identify the offerings that are best for your business.

Tips for Shipping With USPS Domestically
USPS service level USPS shipping rates start at… Delivery times When do I use this option? Packaging tips to get the best USPS shipping rate.
First Class Package Service $3.59+ 1-3 business days For packages weighing less than 1 pound Use your own box, envelope, or poly mailer. Try to find the lightest package possible to keep the price low.
Priority Mail (weight-based) $7.41+ 1-3 business days For packages bigger than a shoebox weighing 1 pound or more Box size does not matter, but weight does. Try to find a lightweight box that’s sturdy enough for the contents.*
Priority Mail Flat Rate $7.60+ 1-3 business days Depends on the Flat Rate option. Generally, use this when your item is heavy (up to 20 lbs.) and traveling farther distances. See our packaging page for specifics. Order USPS Flat Rate boxes and envelopes from the USPS supplies store for free. You must use them to ship this service level.
Priority Mail Cubic $7.11+ 1-3 business days For packages weighing 1-20 pounds that are roughly the size of a shoebox Size matters! Try to find the smallest box or poly mailers possible to get the best rate on shipping.
Priority Mail Express $23.00+ Overnight-2 business days For urgent packages Box size does not matter, but weight does. Try to find a lightweight box that’s sturdy enough for the contents.*

*Just make sure your box weighs under 70 pounds and is smaller than 108 inches in combined length and girth. 

Calculating USPS Shipping Costs

When shipping with USPS, there are several different factors that determine shipping costs.

Delivery Zone

First, we have the distance traveled. In logistics speak, that’s zone. There are nine USPS shipping zones. The zone is based on the distance between the origin and destination addresses. A zone value of 1, for example, would be a very short delivery distance, likely within the same city. If your package is traveling cross country, it will have a much higher zone value, likely Zone 8 or 9. Here’s an example of the shipping zones (and their respective rates) for packages weighing up to one pound.

USPS Zone Example: 

1 pound package via USPS Priority Mail (weight-based)

Weight (pound) Zone 0,1,2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Zone 8 Zone 9
1 $7.41 $7.71 $7.92 $8.63 $9.09 $9.27 $9.55 $15.00

Package Weight

Next, we have weight. Typically, the heavier an item is, the more it costs to mail. Easy enough.

Take heed for this common misconception: when the postage price is calculated based on weight, the size of the box does not matter. Seriously. Get as big of a box as you want, as long as you don’t run into oversized package limits, which would be 108 inches in combined length and girth, with a 70 lb. weight limit.

However, there’s one service level that does not follow weight-based pricing, and it’s a beaut.

USPS Priority Mail Cubic (the one where size matters)

USPS Priority Mail Cubic pricing is the cheapest option by far for anyone shipping items roughly the size of a shoebox that’s more than 1 pound and up to 20 pounds. Historically, it’s only been available to sellers mailing more than 50K small packages a year, but services like Shippo aggregate their volume to grant smaller retailers access to Cubic Pricing.

Overall, the easiest way to figure out the cost of shipping with USPS and to ensure labels are printed accurately is through shipping calculators, like this one that’s built into Shippo and will display the absolute lowest USPS rates available. Just enter the following information to receive an estimate:

USPS Priority Mail Cubic shipping discount example

  • The ZIP code you’re shipping from
  • The ZIP code you’re shipping to
  • Your package type (e.g. custom package, USPS flat rate box, soft pack envelope)
  • Your package’s dimensions
  • Your package’s weight

USPS International Shipping

Fortunately for online merchants, USPS offers robust international shipping, with services to Canada, Mexico, Puerto Rico, and over 190 different countries.

The process of shipping internationally through USPS is quite straightforward:

  1. Choose the service level you want (more on this in just a second)
  2. Order free shipping supplies (or use your own packaging)
  3. Complete any customs forms required by the country you’re shipping to

You can effortlessly ship internationally using Shippo’s web app or API. Visit our International Shipments page to learn more, or follow the steps described in our support documentation to set up international shipments through the Shippo API.

USPS International Shipping Rates

International shippers can choose from the following USPS service levels:

Tips for Shipping With USPS Internationally
USPS service level USPS shipping rates start at… Delivery times When do I use this option? Helpful packaging tips to get the best USPS shipping rate.
First Class Package International Service $7.32+ Varies by destination For packages weighing up to 4 pounds traveling to more than 180 countries. Use your own box, envelope, or poly mailer. Try to find the lightest package possible to keep the price low.
Priority Mail International (weight-based) $34.53+ 6-10 business days For packages more than 4 pounds traveling to more than 190 countries. Box size does not matter, but weight does. Try to find a lightweight box that’s sturdy enough for the contents.*
Priority Mail International Flat Rate $27.10+ 6-10 business days For packages weighing up to 4 pounds traveling to more than 190 countries. Order USPS Flat Rate boxes and envelopes from the USPS supplies store for free. You must use them to ship this service level.
Priority Mail Express International $42.85+ 3-5 business days For urgent packages. Box size does not matter, but weight does. Try to find a lightweight box that’s sturdy enough for the contents.*

*Just make sure your box weighs under 70 pounds and is smaller than 108 inches in combined length and girth.

International Shipping Guidelines

Perhaps unsurprisingly, USPS has certain regulations that sellers must take into consideration when shipping internationally. You must, for instance, ensure you follow both U.S. laws, as well as the laws of the country you’re shipping to.

Review USPS Publication 52, Hazardous, Restricted, & Perishable Mail to ensure that your item is mailable. For example, items like alcoholic beverages, fresh fruits and vegetables, and perfumes containing alcohol may not be sent from the U.S. to any country. It’s also a good idea to review the Individual Country Listing page to check if your destination country permits you to send the item in the first place.

Customs and Paperwork

Additionally, you’ll want to familiarize yourself with international rules, including shipping prohibitions and restrictions, which can be found here. You’ll also likely need to fill out a customs form for any package weighing 16 oz. or more. This can either be done online or at a post office location (or, services like Shippo can handle this for you automatically).

As a note, be aware that handwritten declarations are no longer acceptable and will be returned to the sender. Rather, customers should review the guidance provided by PS Form 2976-R, USPS Customs Declaration and Dispatch Note.

USPS Shipping Software

In order to streamline shipping with USPS and access discounted rates, many sellers use a shipping software such as Shippo. Here’s how it works.

First, you can connect your store so that all of your sales channels are synced into one convenient place. Then, you can start creating discounted shipping labels from USPS. Shippo allows you to easily sync orders, track information, and automate label creation to save time.

When you schedule a pickup with USPS, Shippo will track your shipments, providing your business and your customers total transparency until the moment the package is delivered. As for returns, with Shippo you can automatically create scan-based return labels for inclusion in the package to make the process even smoother (you’ll only be charged if the label is actually used).

Shippo Web App vs. API

There are two ways businesses can connect with Shippo: through our web app or API. The main difference boils down to customization; the API gives you more options for personalization, while the web app provides a straightforward, and easy-to-set-up option. In fact, normal setup can be completed in a matter of minutes.

Curious which option is right for you? We made a handy chart to help you get started.

Sipping Web App vs. API

And, here’s a side-by-side comparison of the web app vs. API for reference.

Cost Savings

Not only can Shippo help you streamline your shipping operations, it can help you save money as well. Shippo offers USPS discounts of up to 90 percent off retail pricing.

Easy Label Creation

Creating shipping labels, especially in large volumes, can be time-consuming. But Shippo makes the process easy, allowing you to set up automations and preferences to speed up the process. You can even choose from different types of packing slips and label formats to support your company’s customer experience.

Ultimately, you’ll spend less time printing labels and more time focusing on your company’s core business activities.

Shipping Supplies

There are two primary types of shipping supplies you need when shipping with USPS — labels and printers.


Labels are a key component in shipping and logistics, and are scanned throughout the shipping process from start to finish. Information found in shipping labels may include:

  • The names and addresses of both mailers and recipients
  • Mailing dates
  • Tracking numbers
  • Package weight
  • Package dimensions

In the case of international shipments, labels may also state the contents of the package. Shipping labels also include information on the specific shipping service level being used, such as First Class Package Service, Priority Mail Express International, etc. Labels cannot be reused, and a new one must be printed for each new delivery.

There are two commonly used types of labels: paper and thermal. Paper is the more traditional option, and is placed on a package using adhesive. Thermal labels use a newer type of technology where heat is used to create an image that is then printed on a sticky-backed shipping label.


Shipping printers have evolved a lot in recent years. E-commerce sellers now use three main types of printer:


Thermal printers are quick and efficient, easy to maintain, and tend to have lower costs in the long run. However, they often require a higher initial investment than other printer options, and generally come with a limited color selection (typically just black).


Inkjet printers are by far the most inexpensive option and cost considerably less than thermal and laser printers. They’re also simple to use and are perfect for creating vivid, color-rich labels. The cons of inkjets printers are that their print speeds tend to be slower and that their ink cartridges have to be replaced frequently, which can add up over time.


Laser printers are another high-speed option, making them a good choice for printing a high volume of shipping labels. Their toner cartridges tend to last longer and have a lower cost per page than other options. The main drawback is they are more costly than inkjet printers, which means higher upfront costs.

Printer Supplies

Additional supplies shippers need to keep on hand include paper, ink, and/or thermal labels for thermal printers. For more details, check out our deep dive on e-commerce printing.

The Rich History of USPS

Though USPS is a mainstay of our modern lives, shippers may be surprised to learn that its history dates all the way back to 1775, when Benjamin Franklin became the first Postmaster General. Still to this day, it remains one of the most reliable, affordable, and convenient shipping options for SMBs and e-commerce sellers.

Now equipped with a basic understanding of USPS shipping rates, how those rates are calculated, international shipping, shipping software, supplies, and the free products and services that are offered by USPS, it should be clear how USPS benefits merchants of all sizes and helps you get business done.

For more on how to save money and time on your USPS business shipping, check out Shippo and sign up for free today.

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