Three major factors make up that calculated USPS shipping rate —
the weight of an order, the distance it must travel to reach the
customer’s door, and the shipping method you select.
1. A Package’s Weight (Actual and Dimensional)
Weight is straightforward… for the most part. How much a package
actually weighs — the number that pops up on your scale after
you weigh it — is the primary means of determining order weight.
But there is an exception.
Sometimes USPS (and other shipping carriers) will work with
what’s known as “dimensional weight” to calculate a shipping
rate. Long story short, it’s a way of figuring out how much
space a package will take up, rather than just how much
it weighs. Here’s how they go about determining it.
Dimensional Weight = (Length x Width x Height) /
You might recognize the first part of that equation from middle
school — it’s the volume of your package! USPS then divides it
by their divisor (166), a digit that brings said volume down to
a reasonable number that’s comparable to the actual weight of
the order. Other shipping carriers may have different divisors;
166 is another common one.
At the end of the day when it’s shipping time, USPS chooses
whichever weight is greater and uses it to determine your
The distance your order needs to travel is definitely going to
play a role in your USPS shipping rate. Like other carriers,
USPS utilizes what are called zones to segment distances, and
they have a total of 8 of ‘em.
Think of zones as waves that fan out from the shipment’s origin
location. The further the package is travelling to, the higher
the zone number. Whichever zone your ship-to address slots into
will be the foundation of your rate, and the higher the zone,
the higher the final price.
3. USPS Shipping Methods
Cheap or expensive, fast or slow, USPS offers an array of
shipping methods for you to choose from. And, as you’d expect,
the method you select will greatly affect your shipping rate.
First Class is the top dog when it comes to cost-effectiveness.
It’s a very cheap method — but only if your shipment is
lightweight. First Class deals exclusively with orders weighing
less than 15.99 ounces, and delivery is guaranteed within 1 - 3
days at a low cost.
As of 2019, pricing for First-Class Mail is also zone-based.
Below are the current rates by zone and weight.
Weight of First-Class Package
COST PER ZONE
Zones 1 and 2
Zones 8 and 9
If a shipment tops a pound in weight, you’re going to be using
Priority Mail, a standard group of USPS shipping methods. Unlike
First Class — where you can package how you please — USPS
includes the packaging for all Priority Mail shipments free of
charge. If it fits in the box, it ships within one to three days
or overnight through its Express option (in urban areas).
Priority Mail Flat Rate
Flat rate is exactly that — flat. Priority Mail Flat Rate
contains an assortment of packaging options, from envelopes to
large boxes, that get charged a single rate, regardless of where
the order’s headed. The smaller the packaging type, the cheaper
the rate, and as long as the items inside the order don’t exceed
weight and dimension limits, it ships.
Priority Mail Regional Box
A variation of Priority Mail that’s only available online,
Regional Boxes come in two flavors — Box A and Box B — that
differ only in size. Compared to Flat Rate, Regional Box rates
are fixed by weight (up to 20 pounds) but vary by distance; you
will be charged by the zone.
For further info on all of USPS’ offerings, from additional
services to USPS package dimensions and other shipping options,
take a look at our
USPS Pricing Tiers
But wait — there’s always more. USPS has a unique way of
pricing; it uses three tiers to ultimately decide your final
Retail pricing is where the most expensive rates are going to
be, mostly because they won’t be discounted. Retail rates are
what you get over-the-counter through a USPS post office.
Commercial Base rates are where the discounts come in. They’re
available through websites like
some USPS-approved third party providers.
Commercial Plus rates are what you get through Ordoro. Think of
them as Commercial Base rates on steroids — they’re the most
heavily discounted rates available. USPS reserves these
exclusively for a limited set of high-volume partners like yours