Understanding Mail Delivery Time From ZIP Code To ZIP Code

ShipNetwork Tip:

You need only the first five digits to send mail. The complete ZIP+4 code does speed up delivery, however, because mail with these codes is easier to sort.

Understanding ZIP Codes

The system of ZIP codes, introduced in 1963, identifies locations in the U.S. down to a specific street. The format introduced in 1963 consisted of five digits. They introduced the ZIP+4 format in 1983 to further refine the process of sending posts. Including ZIP+4, the full ZIP code consists of nine digits.

The digits of the ZIP code show the state, city, and locality of the post being sent. The first digit identifies either the group of states or the exact state to which the post is addressed. The district within the state is identified by the second and third digits of the ZIP code. The fourth and fifth digits narrow it down to a region or street.

So, all the delivery system needs to know to send the mail to a state or group of states is the first digit of the ZIP code. Once you do that, the second and third digits direct the mail to the correct district.

To send mail, you only need the fourth and fifth digits of the ZIP code. These digits show the region or street where the mail should go. These digits show the region or street where the mail should be delivered.

Also, please remember, you need only the first five digits to send mail. The complete ZIP+4 code does speed up delivery, however, because mail with these codes is easier to sort.

The dimensions and form of your parcel are not as significant as the postal code. The USPS transports packages with cremated remains, live animals (including day-old poultry), and hazardous materials between ZIP codes.

Why ZIP Codes Are Translated Into Postal Barcodes

The logic of ZIP codes doesn’t end with nine digits. It extends with postal barcodes.

USPS translates ZIP codes into intelligent barcodes. You are forgiven for wondering why, with ZIP codes giving you all the necessary information, you need postal barcodes. Barcode technology takes the logic of ZIP codes into the digital world, offering all the advantages of digitization.

The intelligent barcode is added to the mail by optical character recognition (OCR) technology by the post office wherein the barcode is punched into the package. Senders can print the barcode themselves if they wish to. This works great for businesses that send out bulk mail because they get discounts for printing the barcode.

One option for businesses is to outsource the process of mailing and printing because professional firms specialized in the field are already compliant with the rules and regulations.

The Four Types of ZIP Codes

The four types of ZIP codes are:

  • Standard ZIP Code. Most direct mails are standard ZIP codes. All addresses are standard ZIP codes, except the following three.
  • Military ZIP Code. Every military base across the U.S. has a military ZIP code, including both moving and stationary bases. These ZIP codes may overlap with others geographically.
  • Post Office ZIP Codes. Such ZIP codes are used to identify PO boxes, with each one having a unique ZIP+4 code.
  • Unique ZIP Code. These are the rarest kind. Big firms are assigned such codes. Some government agencies and higher institutions are assigned these codes as well.

The Factors That Affect ZIP to ZIP Delivery Time

Delivery time for mail sent throughout the U.S. depends on a mix of predictable and unpredictable factors. The ZIP to ZIP distance is constant but things like system malfunctions and breakdowns can’t be predicted.

Not much can be done about this but you can plan for your mail to arrive on time based on the backlog of direct mail, weather, federal holidays, and of course, the distance.

Backlog of Direct Mail

Given the size of USPS operations, the huge quantity of mail dealt with on a daily basis can cause a backlog on any occasion. During peak season and holidays (like Thanksgiving and Christmas), USPS experiences a predictable backlog. You may choose not to send direct mail during this period, but rather plan and send ahead of these occasions.


Conditions like storms and hurricanes affect the USPS's ability to deliver to the affected region. Although the weather is unpredictable, some prefer to check the weather forecast before sending mail.

Federal Holidays

Federal holidays are extremely busy times for the USPS. Christmas is the busiest period of the year and you can expect delayed letter delivery during this time. If your mail transit time is during a federal holiday, you can plan by sending the mail a day or two earlier.


Lastly and most importantly, the distance of the ZIP to ZIP mail delivery impacts the delivery time. Generally, longer distances and a destination in a rural area may mean slower delivery times. You can find delivery times directly on the USPS website.

How Long Does Mail Take From ZIP Code to ZIP Code?

If you want the ZIP to ZIP speed of your mail delivery, you will find several mail time calculators online that purport to do the job. However, most of these calculators aren’t extremely accurate.

The most accurate and best available tool is the USPS delivery time calculator. You can estimate the delivery times of Priority Mail, Priority Mail Express, Standard Mail, and StandardB service types by entering the origin ZIP code and destination ZIP code as well as the service.

If you know when you need your post to arrive, you can schedule it by calculating the ZIP to ZIP mail time.

How Long Does Stamped Letter Delivery Take?

Both business and personal communication are often done by stamped letters. Stamped letters usually bear a paper stamp. Although it isn’t easy to get an exact ZIP to ZIP delivery time of a stamped letter, the following metrics help you get a better idea:

  • Service area. Both source and destination of your ZIP to ZIP stamped letter are included in the service area. If either the origin or the destination of the mail is in a rural area it may mean a longer delivery time.
  • Mail class. Stamped letters may be found in all the defined USPS mail classes. Knowing the mail class to which your letter belongs will help in estimating the ZIP to ZIP delivery time.
  • City name and ZIP code. Almost all senders will enter the correct city name. But the ZIP code is sometimes wrongly entered.

You can arrive at an estimate of your stamped letter delivery time from ZIP to ZIP by checking this map. You need to choose the service, mail class, ZIP, and city name to get an estimate of your stamped letter delivery time.

Regular State-To-State Mail Delivery Time

Some folks want to be able to track state-to-state mail delivery time. You can only do this by buying USPS tracking information when mailing items. This may work for you if you send or receive mail infrequently. Mail delivery times depend on delivery routes, weather, unavoidable circumstances, and much more.

However, suppose you own a marketing business and are mailing promotional materials. Due to the sheer size of the mailings you send out, it isn’t practical to buy tracking information. Also, tracking the receipt of your ZIP to ZIP marketing mail isn’t necessary at all. Its only effect would be to lower your return on investment.

In this and similar cases, if you are an experienced player you will have an idea of when your marketing materials reach their recipients based on factors like distance, delivery routes, and destination. The normal time for regular mail to reach its ZIP to ZIP destination is about three to five days, even when sent to a different state.

State-to-state mail delivery times do vary on occasion due to factors like the destination being in a rural area, and operational/functional emergencies. Having a verified address helps in delivering the mail more quickly.

FedEx and UPS are two of the other popular state-to-state mail delivery services. FedEx offers FedEx Ground (one to five business days delivery), FedEx Express Saver (three business days), and FedEx Overnight (often next-day delivery by 9 a.m.). UPS offers UPS Ground (one to five business days) as well as UPS Next Day Air as well as UPS 2nd Day Air for faster delivery.

The ZIP to ZIP Mail Delivery Process in 5 Steps

To know how long your letter will take to reach its destination with USPS, understand the mail delivery process. By understanding how USPS delivers mail, you can better estimate when your letter will arrive.

  1. The most obvious step: you put the letter in the mailbox.
  2. Your postal carrier picks up the item and takes it to the sectional center facility (SCF) in your city. If you aren’t located in a city, it is taken to the sectional center of the closest city. There are nearly 200 SCFs in the United States. Each SCF serves as a processing and distribution center. They cover one or more three-digit ZIP codes.
  3. The letter is taken to the recipient city’s sectional center after first being transported by plane to the destination state.
  4. The fourth step is letter sorting before it is handed to the postal carrier.
  5. Lastly, the postal carrier delivers the letter to your recipient.
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Each of these steps, however, may involve hidden complications and there is scope for error, hence deliveries are on occasion hampered. Despite following procedures, you may experience a delayed delivery. Compared to the high volume of mail USPS processes daily, the frequency of these occurrences is low.

Does USPS Deliver Every Day of the Week?

Did you know that USPS delivers on Saturdays and occasionally on Sundays? The work schedule of your local post office decides the mail delivery service availability. The usual work week is six-day from Monday to Saturday.

In some parts of the U.S. work happens for five days with a rest of two days. In peak seasons, USPS also delivers on Sundays - though this isn’t a rule.

How Priority Mail & Priority Express Fit In

Do you know if USPS delivers on Saturdays and if it will benefit you? That depends on if you use either Priority Mail or Priority Express. This is because USPS uses Saturdays only for Priority Mail and Priority Express.

If you need to send a mail urgently and have it delivered on a Saturday, choose Priority Mail or Priority Express. Priority Express costs more than Priority Mail. Alternatively, you could decide to send it a day in advance to ensure it reaches by Friday.

The Types of USPS Mail

You can choose to send in any one of the following five types based on their speed of delivery/postal delivery times:

  • USPS Retail Ground
  • Media Mail
  • Priority Mail
  • Priority Mail Express
  • First Class Mail

USPS Retail Ground

If you need a reliable and affordable option for non-urgent deliveries, USPS Retail Ground is a good choice. Ideal for shipping large packages from ZIP to ZIP. You can purchase this service at a post office starting from $8.95.

You pay by the weight of the package and mailing distance. With USPS Retail Ground, you get USPS tracking. Insurance is also available.

Media Mail

If you are sending books of at least eight pages in length, sound recordings, videos, CDs, DVDs, or educational materials, economical Media Mail might be the best option for you. Not all types of media are permitted and there is a weight maximum of 70 pounds per package.

Postage for Media Mail can be purchased at a post office at prices starting from $3.65. Expect your mail to go from ZIP to ZIP within two to eight business days. Pricing includes USPS tracking for packages.

Priority Mail

Priority Mail is the bestselling USPS service. Shipping from ZIP to ZIP is done in one to three business days. Send anything from a postcard to a big box. If your package is 70 pounds or under, you don’t need to weigh it with Priority Mail Flat Rate.

This service provides shipping anywhere in the U.S. for a variety of package types and sizes. Envelopes and boxes are free. You can buy Priority Mail at a post office or online. It comes with both tracking and insurance.

If you are doing bulk mailing, this is an expensive choice. The USPS Priority Mail Delivery Map helps you estimate Priority Mail delivery time.

Priority Mail Express

To mail with the fastest USPS domestic shipping service, opt for Priority Mail Express.

Priority Mail Express includes flat rates for shipments under 70 pounds. Free flat-rate envelopes are available.

You can buy Priority Mail Express at a post office or online at prices that start from $28.75. Again it isn’t a highly economical/practical choice for bulk mail. Also, when using this option your package needs to be ready to mail by 10:30 a.m.

First Class Mail

If you need a mail delivery service for small items, First Class Mail is a good choice. Cost-effective and can handle standard-size single-piece envelopes weighing up to 3.5 ounces. You can also use it for small packages and large envelopes weighing under 13 ounces.

Mail transit time is one to five business days from ZIP to ZIP for mail and two to five business days for small packages. Available at post offices at prices that start from $0.63.

First-Class Mail Delivery Time From ZIP Code to ZIP Code

Many people mistakenly believe that First-Class Mail delivery occurs within a day. This may not be a concern if you are sending non-urgent mail. If your mail is time-sensitive, as when sending out documents, understand that first-class delivery does take up to five days on occasion.

A Timely, Well-Received Mail Results From a Conscious Sending Decision

USPS is an organization that has grown and evolved with experience. However, it is still highly dependent on humans. In a world where emails that are automated bounce, it isn’t easy to imagine how the post can malfunction in the form of postal delays.

Yet if your business depends on your mail arriving on time, you need to take steps to ensure it does, many of which we have outlined in this article. Ensure due diligence like having verified addresses. Using the knowledge outlined in this article, you can choose to send mail via an appropriate service that works economically and arrives on time.

Also, choosing to partner with an eCommerce fulfillment company like ShipNetwork may help your business in being flexible, and economical, as well as scale up when the time demands it.

Take the first step in what may be a new vista for your business by Requesting a Quote from the eCommerce shipping pros at ShipNetwork and discovering a newer and better way to send mail.

ZIP to ZIP Mailing Checklist

  • Ensure your mail has the correct ZIP code.
  • Allow for ZIP to ZIP delays due to weather, federal holidays, deliveries to rural areas, and deliveries on weekends.
  • If delivery is set to reach on a Saturday, consider using Priority Mail.
  • Barcode your mail yourself if you are sending bulk mail (for cost savings).
  • Find out delivery time using the mail time calculator on the USPS website.
  • Recognize that there is plenty of room for human error in the delivery process.
  • The USPS provides different types of mail services. Choose your preferred type based on price, delivery time, and size of the package.
  • Partner with a logistics specialist company to benefit from their expertise.


How Was a Mail Sent Before ZIP Codes Were Invented?

Before ZIP codes, mail was hand-sorted and often passed the experienced hands of ten postal workers on the way to its destination. It relied heavily on local knowledge and was more prone to error.

Why Does Mail Send to Rural Areas Take More Time?

The mail processing central hubs are usually close to cities, which means sending to rural areas takes more time.

Can I Send My Mail by Any of the Types of USPS Mail?

Each type of USPS mail has requirements including size, shape, and weight. Find the best one for you.

Can I determine how long my mail will take before I send it?

Yes, you can estimate mailing time using the USPS mail time calculator online.

I Have a 16-Millimeter Film I Want To Send Across. Does USPS Deliver Such Mail?

Yes, you can use USPS Media Mail to send 16mm or smaller films and other types of media."

What Are the Options To Send Mail Within the U.S. Other Than USPS?

The other mailing options for U.S. residents include UPS and FedEx.

What Is Commercial Mail?

Commercial Mail is a mailing service for bulk-mailing commercial services that qualify for a lower rate.

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