The United States Postal Service, known as USPS, is a
popular carrier used by e-retailers of all sizes. As an
agency of the United States government, it’s a bit unique
compared to other shipping carriers, offering a diverse
selection of shipping services that are both cost-effective
USPS offers plenty of shipping methods for delivering orders of
all shapes, sizes, and weights.
First Class Mail
USPS’ First Class Mail is legendary for its cost-effectiveness —
but only if your shipment is lightweight. First Class deals
exclusively with orders weighing less than 15.99 ounces,
delivering them within 1 - 3 days at low rates.
When it comes to First Class, the packaging is in your hands.
USPS doesn't offer supplies (like they do with other methods),
and they have dimensional requirements on such shipments:
Once your shipment surpasses 15.99 ounces and weighs a pound,
it’s time to use USPS’ Priority Mail. With a weight limit of 70
pounds, Priority Mail offers plenty of options for shipping, all
in the form of boxes.
Unlike First Class, USPS provides the packaging for Priority
Mail shipping, and — best part is — the supplies are all free of
charge. If it fits in the box, it ships within one to three
Because Priority Mail is a catch-all for all shipments weighing
a pound or more, there are a few box choices to choose from.
Priority Mail Flat Rate
The words “Flat Rate” are exactly as they sound. Flat rate
essentially means if you ship an order via a USPS Flat Rate box,
you get charged a single rate, regardless of where it's going.
The smaller the box, the cheaper the rate, and as long as the
order fits in the box and weighs less than 70 pounds for boxes
and 4 pounds for envelopes, you’re good to go.
PRIORITY MAIL FLAT RATE BOXES
Flat Rate Envelope
12.5" x 9.5"
Legal Flat Rate Envelope*
9.5" x 15"
Padded Flat Rate Envelope**
12.5" x 9.5"
Small Flat Rate
8.6875" x 5.4375" x 1.75"
Medium Flat Rate (Top Loading)
11.25" x 8.75" x 6"
Medium Flat Rate (Side Loading)
14" x 12" x 3.5"
Large Flat Rate (Side Loading)
12.25" x 12.25" x 6"
APO/FPO Large Box***
12.25" x 12.25" x 6"
*A legal envelope is a slightly larger envelope that’s usually
used to transport legal documents.
**Padded envelopes are exactly as they sound — envelopes lined
with bubble padding that adds an extra layer of protection for
more fragile orders.
***APO and FPO options refer to military locations, with the
former indicating an Army Post Office and the latter a Fleet
Priority Mail Flat Rate also has a hastier option, dubbed
Priority Mail Express, that delivers shipments within a day at a
flat rate. Packaging dimensions are the same, but only Flat Rate
Envelopes, Legal Flat Rate Envelopes, and Padded Flat Rate
Envelopes are usable.
Priority Mail Regional Box
Coming in two forms, Box A and Box B, Priority Mail Regional Box
is a shipping method available only online. How much you pay for
Regional Rate boxes varies based on the distance they’re to be
delivered. But like Flat Rate, weight plays a diminished role —
the distance, or zone (which we’ll get to later), is what
The only difference between Regional Rate Box A and B is size
and weight limit:
REGIONAL RATE A
11.0625" x 2.5" x 13.0625"
10.125" x 7.125" x 5"
REGIONAL RATE B
14.5" x 3" x 16.25"
12.75" x 10.5" x 5.5"
USPS Retail Ground
Formerly known as Standard Post, USPS Retail is a way of
shipping orders weighing up to 70 pounds within 2 to 8 days.
Because of that larger window, Retail Ground is cost-effective,
but unpredictable. It’s also restricted to retail rates only, so
it’s only available over the counter at one of USPS’ facilities.
Like Retail Ground, USPS Mail Media ships orders within 2 to 8
days — but they only ship educational materials. And that can
include a range of things:
Physical records like CDs, DVDs, or cassettes
Printed educational materials
16 millimeter or narrower film
You get the idea — if it’s media-related, it may qualify. But
USPS is picky about what orders are eligible for mail media. No
video games, digital drives, or any advertisements are allowed.
Like most carriers, USPS offers international options.
Priority Mail Express International
Delivering in three to five business days,
Priority Mail Express International is a global
version of your domestic Priority Mail Express.
It offers both flat-rate pricing — if it fits in
the box, it ships — and the usual pricing based
on weight or destination.
Global Express Guaranteed
Their quickest and most expensive international
option, Global Express Guaranteed ensures global
delivery in one to three days.
Priority Mail International
This method is pretty much the spitting image of
Express International, but it’s a longer
delivery timeframe of six to eight days at a
The total cost to ship will be determined by a few factors —
actual weight or dimensional weight of a shipment, the shipping
method you’ve selected, the zone it’s headed to, and any
additional charges. Let’s dig into each.
It’s straightforward: how heavy an order is will impact your
shipping rate, and the heavier it is, the higher your rate will
go. Not much can be done to reduce the weight of your product,
how it’s packaged will matter.
And that’s not just because of heaviness — it’s also because
USPS may apply dimensional weighting instead of using an order’s
Actual weight is simple; it’s the weight of your order in
ounces, pounds, grams, or kilograms. But in some circumstances,
USPS will charge your rate based on dimensional weight, a way of
finding cubic weight based on dimensions. How it all works:
Dimensional weight calculation = (Length x Width x Height)
That last number — 166 — is known as a volumetric divisor, a
number USPS chooses to determine rates. Compared to some of the
carriers, USPS doesn’t use dimensional weight too frequently.
They only apply it to Priority Mail parcels larger than one
cubic foot that are headed to zones 5 - 9, a pretty lengthy
For instance, let’s say you’re shipping through Priority Mail’s
Regional Rate Box A (side loading) and your order weighs 3
pounds. Your dimensions will be 11.0625" × 2.5" × 13.0625".
Multiply them together, divide by the divisor, and that’s 361
cubic inches, making dimensional weight 2.17, or 2 rounded down.
When the order is shipped out to zones 5 - 9, your rate will not
be determined by dimensional weight. Instead it’ll be based on
the actual weight: 3 pounds. Why? Because USPS — and other
carriers — will charge you based on which of the two is higher.
For all services other than Flat-Rate, distance is determined by
the area where an order’s destination is located, called a
Get to know what zones are, as nearly all shipping carriers use
the term! They’re essentially ranges of distance that echo out
from the location an order is shipped from. Whatever zone your
destination ends up falling in will be the zone that determines
your rate, and the greater the zone, the higher the cost.
For a look at how zones map out around your ship-from location,
enter your zipcode into this
provided by USPS.
Compared to other carriers, USPS is lax when it comes to fees.
But they do offer several additional services to complement
their shipping methods. Of course, many will come at additional
cost, and some are free of charge depending on shipping method.
With the exception of Priority Mail Express and
Priority Mail shipments (free of charge, they
include $100 and $50 respectively), you’ll have to
pay for shipping insurance. Based on the declared
value (the amount you want insured), it’s $2.10 per
Hold For Pickup
For valuable shipments, a pickup can be arranged
where customers head to a designated post office to
retrieve their packages. It’s completely free.
All packages include tracking, which allows you and
the customer to keep tabs on an order as it makes
its way to its destination.
For fragile items, USPS will handle it with extra
care, so long as you’re willing to pay $10.25 per
Certificate of Mailing
In the event that there’s a dispute, it’s up to the
shipper, not USPS, to offer up evidence that an item
was sent. It will cost $1.35 to get a Certificate of
Mailing that does exactly that by recording the date
USPS received your shipment.
Collect on Delivery (COD)
At $7.15, you can choose to let the customer pay for
their purchase and cost to ship at the moment of
Take delivery security a step further and receive a
receipt as proof that a delivery was attempted or
made to the order’s address. If a Return Receipt is
purchased (costs $1.45 per delivery), you can also
require a signature confirmation from the customer.
To absolutely ensure delivery, you can pay $2.45 per
package to require a more specific signature:
Only allow a specified person to receive a
shipment. This service is only available to
those who purchase Certified Mail, Collect
on Delivery, Registered Mail, or Signature
Confirmation, at a cost of $8.30, $4.95,
$4.95, and $7.40 respectively.
Adult Signature Restricted
Only allow the release of a shipment if an
adult 21 years of age or older signs. Costs
$5.90 per shipment.
The way USPS prices also distinguishes it from other shippers.
There are three tiers that determine a USPS rate price — Retail,
Commercial Base, and Commercial Plus. The rates for every
shipping method we've mentioned fit into one of these three
categories based on how you're accessing postage.
Retail rates are over-the-counter rates; they're
what you'd pay if you walked into your nearby USPS
post office to ship a package. They tend to be more
expensive than other rates.
Commercial Base Rates
Commercial Base rates are discounted and available
through USPS postage providers like
Pitney Bowes. USPS only offers Commercial Base through approved
postage providers, and merchants must purchase
through them in order to access the rates.
The most heavily discounted, Commercial Plus rates
are available exclusively to qualified high-volume
shippers. Fulfillment warehouses, large retailers,
and shipping software providers (such as ourselves)
are able to access these rates due to the large
number of shipping labels they produce.
Given the complexities, coming up with your rates on your own
with 100% accuracy is a difficult task. To figure out USPS
shipping rates on your own, take a look at their
Or feel free to log into Ordoro, import your orders, and plug in
your shipping specifics to find an accurate rate.
Don't have an account?
to get set up and access our
USPS shipping rates with
discounts of up to 67%!
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