Before you start shipping or start to create custom packaging for your business, it’s good to be aware of the maximum box dimensions to ship with the US Postal Service. We’ve listed all of that information below for the corresponding mail classes. First, you’ll need to know what the girth of your package is.
Table of Contents
- How to Calculate the Girth of Your Package
- Maximum Dimensions for Domestic Mail Classes
- Maximum Dimensions for International Mail Classes
- What About Minimum Dimensions?
- Beware of New Non-Standard Fees from USPS
How to Calculate the Girth of Your Package
To calculate your package’s girth, take the two smaller dimensions of your package (we’ll use Width and Height in this example), and add those two numbers together. Then, multiply that sum by 2 to get the Girth. The formula should look like this:
Girth = 2*(Width + Height)
Maximum Dimensions for Domestic Mail Classes
- Maximum Dimensions: 22″ x 18″ x 15″
- Maximum Length + Girth: 108 inches
Priority Mail Express
- Maximum Length + Girth: 108 inches
Priority Mail Cubic
- Maximum Dimensions for boxes: No one dimension can exceed 18 inches, and total volume can’t exceed 0.5 cubic feet
- Maximum Length + Width for poly mailers and envelopes: 36 inches
Retail Ground (or Parcel Select Ground)
- Maximum Length + Girth: 130 inches
Maximum Dimensions for International Mail Classes
First-Class Package International
- Maximum Dimensions: 24″ in Length, Length + Width + Height: 36″
Priority Mail International
- Maximum Length + Girth: 108 inches (varies by country—check USPS’ individual country codes for restrictions)
Priority Mail Express International
- Maximum Length + Girth: 79 inches (varies by country—check USPS’ individual country codes for restrictions)
What About Minimum Dimensions?
They say good things come in small packages…but USPS does have a minimum package size requirement! When shipping a box, the minimum dimensions are 6x3x0.25″. This rule applies for any USPS mail class you decide to ship in.
USPS could technically reject your package if your box is smaller than those dimensions, but the chances of that happening are pretty rare. However, we always suggest using a box that’s at least as big as the minimum dimensions. If there’s no way for you to do that, we recommend putting the box into a small poly mailer envelope when you ship it.
Pro Tip: If you use free USPS boxes, you won’t have to worry about minimum dimensions at all…but you may have to worry about some new surcharges if you exceed certain dimensions! We’ll get into that below, but in the meantime, you can check out our guide that lists the dimensions of all the free USPS boxes if you’re in the market for some free packaging.
Beware of New Non-Standard Fees from USPS
In April 2022, USPS began imposing “non-standard fees” on packages, which are basically surcharges for being over a certain size. USPS never hit shippers with surcharges the same way UPS and FedEx did, but the Postal Service introduced these new surcharges in order to offset inflationary pressures from rising fuel and transportation costs.
The new USPS non-standard fees are as follows:
- $4 if any length of your package exceeds 22 inches but is less than 30 inches
- $15 if any length of your package exceeds 30 inches
- $15 for packages greater than 2 cubic feet in volume
- $1.50 for missing or incorrect dimensions that result in any of the above non-standard surcharges; you can think of this as an “overdraft” fee that USPS charges for imposing any of these non-standard fees
To learn more about these new USPS surcharges, check out our article: USPS Non-Standard Fees: A Guide to Understanding the New USPS Surcharges.
21 CommentsPost a Comment
Price for a package 24 by 18 by 24. Lawrenceville nj to Houston tx
Shouldn’t have to go to another page to determine the MAXIMUM ALLOWABLE WEIGHT 70 lbs.
I agree. This website is confusing for us older people.
Pro tip incorrect. Post office surcharges on their priority mail small triangular shipping box and possibly others
Hi Steven, thanks for your comment! You’re right – I had yet to update the article to incorporate the new non-standard fees USPS introduced in April. I appreciate you pointing that out. I’ve updated the article to include those new surcharges!
Can I get a recliner in small packets delivered to me because that’s is coming To me by the 17 of this month
I just got a text from USPS they my package
Mi pedido debio de llegar hace 15 días y ya tiene aparte de los 15 días, 2 semana en camino 🙆♀️Estoy desesperada
Need a. Need a box 19″by 15″
Buenas yo tenía que recibir un paquete para el día 21 de septiembre y no me ha llegado nada al currier si es posible me pueden responder
GENESIS YARITZE JUAREZ HERNANDEZ
BUENAS TARDES YO TENIA QUE RECIBIR UN PAQUETE 17 de enero y no me ha llegado
Hola . Tenía que llegar un paquete internacional a Hialeah ami casa pero sale que llego el 18 de septiembre y nunca se recibió nada .pueden ustedes verificar si esta en su oficina postal gracias nunero de pedido 17-07557-26855
Jimoh sodiq abiola
Pls some package was sent to me since 27th of July and till now , I haven’t received any call from USPS agent, when I tracked it , it shown that that package is Cincinnati since 30th of July and till now no upfront information about than the same Cincinnati, the tracking code start with ch, pls for how long am I going to expect this to be arrived advise me oool
Hi Jimoh – I’m sorry you’re on the hunt for this package! We don’t handle any packages at Shipping School, so we can’t tell you where it is. Your best bet at this point is to create a USPS account and submit a missing mail search request. You can do that here. I hope this is helpful!
Do you have store at Staten Island NY?
Can I use ISPS to ship box 18x18x18x18. ?
Hello! I want to ship some cards of good wishes and letters to my lover in Boston but I’m in Nigeria and River State currently. However,I never mailed once through USPS Internationally.
Nevertheless, please tell me the cost for 5kg parcel following my location to my lover’s location.
Hi Adaeze – I’m sorry I can’t help more, but I only can point you in the direction of a quote for a shipment originating in the United States, not coming from Nigeria and going to the United States. You could try the UPS or FedEx website, assuming they have service in your country.
I would like to know when item # CP064201552UA will arrive at Boca Raton wineries in Miami. Thank you
A list of the empty boxes for sale by USPS would allow me to plan shipping from Mata to France the goods and belongings that I decided to keep at the iccasion of my reasignment.^
from Malta to France