Flat Rate Shipping

What is flat rate shipping & how much does it cost? Read more below.

If you are shipping a lot of packages over long distances within the US or internationally, you might be wondering whether Flat Rate shipping is the right service for your needs. There’s a lot to learn about using Flat Rate shipping and when it is and is not economical, so let’s find out more! Flat Rate shipping is ideal if you are sending heavy items or items that need to travel long distances. It is charged by size, not weight or zone, so it makes it cheaper to send these items. However, it may be more expensive if you are sending light items locally. Make sure you always compare it with zoned shipping to get the best prices.


usps package in a mailbox


What Is Flat Rate Shipping?


Flat Rate shipping is a service provided by USPS for customers that want to send their items according to their size, rather than their weight and destination. Some other couriers, such as FedEx and UPS, also have versions of Flat Rate shipping. FedEx’s service is called Flat-Rate, but UPS’s is referred to as Simple Rate. Regardless of the name, this is a very popular service that many people make use of when sending mail, and it can save you a lot of money on certain items. It is important to look into Flat Rate shipping if you are mailing items over long distances and you want to keep your prices low. Both businesses and individuals can benefit from this kind of mailing service, and it also makes calculating shipping rates much easier.


A Flat Rate box will cost the same whether you are sending it next door or across the country. It will also cost the same whether you are mailing a box of feathers or a box of lead (provided that the box size is the same). That means you can easily predict the shipping costs and you don’t need to spend time calculating them according to these changing variables. All you need to do is work out what size box your item requires, fill it, and ship it. This takes away some major headaches when it comes to trying to work out the best shipping methods, especially for businesses that may need to mail items to various parts of the country. You can simplify your whole shipping calculation by using the Flat Rate boxes.


What Is Zoned Shipping?


Zoned shipping is what most shipping relies upon, and it means that the cost of a package depends upon the weight of the package and how far it is traveling. The US is split into 8 zones, with outlying US territories making up the 9th zone. The zones vary according to where you are, with low number zones being the closest areas, and high numbers being the furthest from you. For example, if you are in Los Angeles, places like Phoenix and Las Vegas will be in zones 1-4, while New York would be in zone 8. The same would be true in reverse.


That means the zones change depending on where you are located, and this can make zoned shipping hard to calculate. The further the package is traveling, the more it will cost to mail it. Zoned shipping is generally also charged by weight, and it can cost a lot to send a package to the furthest zones if it is heavy. Even light packages may be expensive if you are sending them a long way. This is where Flat Rate comes in.


Is Flat Rate Better Than Zoned?


Flat Rate shipping isn’t always better than zoned, but often it is. When you are mailing a package, it’s a good idea to compare the zoned weight against the Flat Rate. For example, sending a Flat Rate envelope would cost $8.95, while a 1 lb. package to zones 1 and 2 would only cost $8.70 if it was sent with zoned shipping. However, as the package gets heavier and travels further, the Flat Rate service quickly becomes the most economical option, and many people swap to it to save some money.


At the other end of the scale, sending a 70 lb. package to zone 9 would cost you around $364.85 with standard Priority Mail, while the largest Flat Rate package would cost $21.50 and can weigh up to 70 lb. too. It’s clear why Flat Rate services are so much more appealing if you’re shipping things over a long distance and trying to keep your postage costs low. Flat Rate travels at the same speed as the Priority Mail service, so the two are otherwise equivalent.


packages in a mailbox


What Are The USPS Sizes For Flat Rate?


Of course, one of the slight downsides of Flat Rate mail is that you must send things using the predesignated boxes, so you can’t choose your own sizes for the packages that you wish to send. If your item doesn’t fit easily into a Flat Rate box, you might find this service isn’t suitable for you. That said, there is quite a lot of flexibility in the different size options, so let’s explore the different sizes you can utilize.


The Flat Rate Envelope measures 12 ½ inches x 9 ½ inches.


The Window Flat Rate Envelope measures 10 inches x 5 inches or 12 ½ inches by 9 ½ inches.


The Small Flat Rate Envelope measures 10 inches x 6 inches.


The Padded Flat Rate Envelope measures 12 ½ inches x 9 ½ inches.


The Legal Flat Rate Envelope measures 15 inches x 9 ½ inches.


The Small Flat Rate Box measures 8 5/8 inches x 5 3/8 inches x 1 5/8 inches (internal dimensions)


The Medium Flat Rate Box (type 1) measures 11 inches x 8 ½ inches x 5 ½ inches (internal dimensions).


The Medium Flat Rate Box (type 2) measures 13 5/8 inches x 11 7/8 inches x 5 ½ inches (internal dimensions).


The Large Flat Rate Box measures 12 inches x 12 inches x 5 ½ inches (internal dimensions)


The Large Flat Rate Board Game Box measures 23 11/16 inches x 11 ¾ inches x 3 inches (internal dimensions).


What Are The UPS Sizes For Simple Rate?


If USPS’s sizes don’t match your requirements, you might want to look at other couriers. UPS may work for you, and also offers a range of sizes.


The Extra Small Box measures 4 inches x 4 inches x 4 inches, or 6 inches x 4 inches x 4 inches, or 8 inches x 6 inches x 2 inches.


The Small Box measures 6 inches x 6 inches x 6 inches, or 8 inches x 6 inches x 5 inches, or 12 inches x 9 inches x 2 inches.


The Medium Box measures 8 inches x 8 inches x 8 inches, or 12 inches x 9 inches x 6 inches, or 13 inches x 11 inches x 2 inches.


The Large Box measures 10 inches x 10 inches x 10 inches, or 12 inches x 12 inches x 7 inches, or 15 inches x 11 inches x 6 inches.


The Extra Large Box measures 12 inches x 12 inches x 12 inches, or 16 inches x 12 inches x 9 inches, or 18 inches x 12 inches x 6 inches.


As you can see, you get more flexibility with UPS’s boxes, and the prices are comparable with USPS’s. For example, the Extra Large Box with UPS costs from $24.30, while USPS’s Extra Large Box costs $21.50, but USPS’s offering is smaller. It’s worth noting, however, that UPS only allows you to ship packages up to 50 lb., while USPS allows packages to be shipped up to 70 lb.


fedex package


What Are The FedEx Sizes For Flat Rate?


FedEx also offers some flexible options for those wishing to use the Flat Rate service.


The FedEx Envelope is 9 ½ inches x 12 ½ inches, or 9 ½ inches x 15 ½ inches.


The FedEx Pak is 10 ¼ inches x 12 ¾ inches, or 12 inches x 15 ½ inches (other sizes available).


The FedEx Small Box is 10 7/8 inches x 1 ½ inches x 12 3/8 inches, or 8 ¾ inches x 2 5/8 inches x 11 ¼ inches.


The FedEx Medium Box is 11 ½ inches x 2 3/8 inches x 13 ¼ inches, or 8 ¾ inches x 4 3/8 inches x 11 ¼ inches.


The FedEx Large Box is 12 3/8 inches x 3 inches x 17 ½ inches, or 8 ¾ inches x 7 ¾ inches x 11 ¼ inches.


The FedEx Extra Large Box is 11 7/8 inches x 10 ¾ inches x 11 inches, or 15 ¾ inches x 14 1/8 inches x 6 inches.


The FedEx Tube is 6 inches x 6 inches x 38 inches.


The largest FedEx box costs from $39.10, so it is more expensive than the other two options, and slightly smaller than the largest UPS box.


Like UPS, FedEx has a 50 lb. limit on its Flat Rate services, and if the package is over 50 lb., you will have to choose another mailing option.


Can You Use Your Own Packaging For Flat Rate Mail?


This depends on the courier that you choose. If you are using USPS’s Flat Rate mail service, you will need to use the branded boxes, as USPS does not permit customers to use their own packaging for this service. However, if you are using UPS or FedEx to send your mail, you may use your own boxes, provided that the packaging is sturdy enough. You will need to make sure that the boxes fit within the size stipulations, or you will be charged extra.


All three of these companies provide packaging for their customers to use when utilizing the Flat Rate service. This ensures that customers can easily fit their mail to the size stipulations, and there is no hassle involved in finding a box that is the right size. The boxes are available for free, but must be used for the Flat Rate shipping service. Using them for anything else is prohibited. You can generally order the boxes from the respective couriers’ websites, or pick the USPS boxes up at your local post office.


How Fast Does Flat Rate Mail Travel?


The shipping speed depends on the courier sending the item. USPS ships their Flat Rate mail using the Priority Mail service, and it should arrive within 1 to 3 business days. UPS offers various shipping speeds, charged accordingly, and you can choose 5 day shipping, 3 day shipping, 2 day shipping, or next day shipping.


FedEx also offers a choice of shipping speeds, with mail being delivered in 3 business days, 2 business days, or 1 business day. This ensures that you can choose the right service for your needs, and the increased flexibility may lead to you choosing one of these couriers, as opposed to USPS.


Is Flat Rate Mail Insured?


USPS offers up to $50 insurance on Flat Rate mail, while FedEx and UPS offer up to $100 insurance on their equivalent services. This is another reason that you might choose one of these alternative couriers if you are sending expensive items, although USPS is generally the cheaper option.


Should I Use Flat Rate Mail?


It is always a good idea to compare the cost of the Flat Rate service against the cost of zoned shipping, but in general, heavy and long-distance items are best sent with Flat Rate, regardless of which courier you choose. It is only likely to be cheaper to use zoned shipping if the package is light and the destination is nearby.


virtual mailbox on desktop




Receiving mail can be a frustrating and chaotic aspect of life, and if you get a lot of junk mail or you’re never at home to sign for packages, you might want to consider getting a Virtual Mailbox from US Global Mail. This provides you with a secure, permanent mailbox where you can get mail dropped off and packages signed for at any time of day. You can then review scans of the mail online, and decide what action to take. Packages can be forwarded to your address, or you can have letters opened and securely scanned so you can view the contents online.

Virtual Mailbox for your Postal Mail

Access mail & packages online 24/7. Try it free.

A better way to manage mail.

Why pickup your mail in person, when you can get it on your phone? Try it free. Cancel anytime!
Contact us



No contract. No hidden fees. 100% satisfaction guarantee

  • 1 name on the account
  • Unlimited mail scans
  • Free check deposit

All our plans come with

100% Guarantee

Don't love it? Cancel within 30 days for a full refund.

location on the map
Permanent Street Address

Get a PO box online while maintaining a real street address.

computer devices
Smart Mailbox

Read all your mail virtually. No paper mess and a greener planet.

No limits

Get mail from all your homes and business(es) or both in the same app.

security symbol
Free Check Deposit

Deposit bank checks virtually... with the click of a button.

flexible plans
Flexible Plans

Upgrade, downgrade, cancel anytime.

Tree on the top of the world globe

We want to leave a greener Earth for our children

We plant a tree for every new member sign up

Recent blog posts

paypal on a phone

Purchase Postage Through PayPal Without Ebay

How can you purchase postage through PayPal without Ebay? Read more below.

Read more

Overnight Shipping USPS

What is Overnight Shipping USPS and how much does it cost? Read more below.

Read more
usps truck driving on the road

How does USPS Priority Mail Express work?

What is USPS Priority Mail Express & how much does it cost? Read more below.

Read more