Extra Postage Required


March 16, 2024

Have you ever received a letter or a greeting card with the disheartening phrase “Extra Postage Required” stamped on it? You’re not alone. 

Many people find themselves puzzled by this unexpected demand, wondering why their seemingly regular mail now carries an additional cost.

This article explores the reasons behind extra postage requirements, such as weight limits and mail with nonmachinable characteristics. At the same time, this write-up discusses how you can avoid additional mailing costs.

Whether choosing the right envelope size, using postage stamps like Forever stamps, or deciding when to mail wedding invitations, this article offers clarity and practical advice.

For FAQs (Frequently Asked Questions) and the latest updates on postage rates and other postal information, be sure to visit FindPostOffice.org, your trusted resource for all things postal.

Why Does My Card Envelope Say “Extra Postage Required”?

Extra postage is required when a mailpiece exceeds its category’s standard size, weight, or thickness limits. Additional postage may also be necessary if you’re sending mail with nonstandard shapes or enclosures.

The “Extra Postage Required” label typically appears when the postage applied to your mail is insufficient to cover the cost of its delivery. 

Extra postage requirements may arise due to various factors, whether it’s a greeting card, gift card, wedding invitation, or any other type of mail.

What Does Extra Postage Required Mean?

“Extra Postage Required” means your mail lacks the necessary postage to ensure its successful delivery.

The postal service requires that postage be calculated and affixed to your mail to cover transportation costs. Additional postage is needed to compensate for the shortfall when this doesn’t happen.

Reasons for Extra Postage Requirement

Some common reasons why your mail may fall short in the postage department include the following:

The Package May Be More Than the Required Weight

One of the factors leading to extra postage requirements is exceeding the weight limits set by postal regulations.

Different mail categories have distinct weight limits. If your piece surpasses these limits, you’ll need to pay extra to cover the increased cost of handling and delivery.

Nonmachinable Mail Pieces

Certain mail items, often those that are oddly shaped, rigid, or have nonstandard elements, are classified as nonmachinable.

Nonmachinable mail requires special handling, which comes at an additional cost. If your mail falls into this category, it will be subject to extra requirements.

If You Cannot Visit the Post Office

When visiting the post office isn’t feasible, managing extra postage requirements becomes a matter of utilizing available resources. 

Begin by weighing your mail and consulting your local postal service’s guidelines to determine the correct postage amount. Online postage calculators can aid in this process, and purchasing postage online or through self-service kiosks offers convenient alternatives.

The Rate for Additional Ounces

The rate for additional ounces when extra postage is required can vary depending on the postal service and the type of mail being sent. 

As of January 2023, the USPS postage rate for a First Class Mail Letter is $0.66, and each additional ounce is $0.24.

How to Avoid Not Having Enough Space for Your Postage

Consider the size and weight of your mail to help prevent the need for extra postage. Be mindful of the following aspects:

What Size Envelopes Require Additional Postage?

The size of your envelope can impact the postage required. Oversized, square and oddly shaped envelopes often incur additional postage costs.

As per USPS.com, the largest allowable dimensions for an envelope are 11 ½ inches by 6 ⅛ inches and ¼ inch thick. 

If an envelope surpasses any of these size limits or weighs more than 3.5 ounces, it is categorized and charged at the rate for a large envelope, also known as a flat.

Postage Cost of Greeting Card

Greeting cards and gift cards usually require extra postage requirements, particularly around the holiday season.

Understanding the postage requirements for these cards is beneficial to ensure your greetings don’t come with unexpected costs.

As of 2023, greeting cards enclosed in standard-sized, rectangular envelopes are typically priced at $0.66. However, if you send square, oversized, or unusual envelopes, the postage cost can begin at $1.06.

For those who prefer sending postcards, standard-sized, rectangular postcards can be mailed with postcard stamps starting at a rate of $0.51.

Note on Greeting Cards and Examples of Greeting Card Postage Costs

Standard greeting cards sent via USPS can typically be mailed with the cost of a single postage stamp.

 As of 2023, a 1oz First-Class Mail postage stamp is priced at $0.66 at the Post Office.

 Smaller greeting cards that don’t require envelopes and fall within the size range of 5″ L, 3.5″ H, 0.007″ W to 9″ L, 6″ H, 0.016″ W may also qualify for postcard pricing.

 In 2023, a First-Class Mail postcard stamp can be obtained at the Post Office for $0.51.

Greeting cards come in various shapes and sizes, and their postage costs vary accordingly. Here are some examples:

Christmas Cards

A typical Christmas card has dimensions of 8″L x 5″H x 0.25″W and weighs 2oz. However, it exceeds the maximum letter height of 6.125″. Due to its uniform thickness and slight flexibility, it falls into the category of a large envelope.

The recommended service is to pay the 2oz First-Class Mail Large Envelope/Flat rate.

Large Musical Greeting Card

A large musical greeting card typically measures 6.5″ L x 6.5″ H x 0.25″ W and weighs 1.5oz. Like Christmas cards, it surpasses the maximum letter height of 6.125” and falls under the category of a large envelope. 

You may have to pay the 2oz First-Class Mail Large Envelope/Flat rate for a card of this size.

Small Square Greeting Card

A small square greeting card has dimensions of 5.5″ L x 5.5″ H x 0.25″ W and a weight of 2oz. It does not adhere to the aspect ratio criterion for a letter due to its square shape and aspect ratio of less than 1.3.

Despite being uniformly thick, slightly flexible, and within letter-size dimensions, it qualifies for First-Class Mail. However, due to the aspect ratio issue, it is categorized as nonmachinable.

The suggested service is to pay the 2oz First-Class Mail Large Envelope or Flat rate, along with an additional nonmachinable surcharge.

Letter Size Greeting Card

A letter-size greeting card typically measures 6.25″ L x 5″ H x 0.125″ W and weighs 2oz. It is uniformly thick, slightly flexible, within letter-size dimensions, and adheres to the aspect ratio criterion.

It qualifies for First-Class Mail, and the suggested service is to pay the 2oz First-Class Mail rate.

Nonmachinable Greeting Cards

Nonmachinable greeting cards usually result in extra postage. These cards often deviate from standard envelope shapes or contain nonstandard elements like buttons, bows, or embellishments.

“Rigid” Letter-size Pricing

Some cards are classified as “rigid” by postal regulations. Due to their inflexibility, these cards often need to be processed separately and incur additional postage costs.

Large First-Class envelopes (flats) that exceed the allowable dimensions, have nonrectangular shapes, or lack uniform thickness are charged package prices and shipped with USPS Ground Advantage.

Sending Oversized Greeting Cards

Oversized greeting cards, whether for birthdays, weddings, or other special occasions, typically require extra postage due to their nonstandard dimensions.

How Much Is Extra Postage on a Greeting Card?

As of October 2023, the cost of mailing domestic postcards is $0.51, while international postcards are priced at $1.50.

The cost of extra postage on a greeting card can vary based on many factors. It’s advisable to weigh your card and check the postal service’s guidelines to determine its exact amount.

If you’re sending greeting cards, invoices, or lightweight merchandise, First-Class Mail is your go-to for reliable and cost-effective shipping. Here are some features and shipping costs for the eligible mail items.


First-Class Mail letters must adhere to specific dimensions, which are under 6⅛” in height, 11½” in length, and ¼” in thickness. 

The U.S. Postal Service offers two pricing options for these letters: stamped and metered.

Stamped letters use traditional postage stamps, whereas metered letters have the postage printed directly onto them. 

Here are the rates for both categories of First-Class Mail letters, based on data from October 2023:

Stamped First-Class Mail Letters
Metered First-Class Mail Letters


A standard-sized postcard should be at least 3½” by 5” in height and length and 0.007” thick. It should not exceed the dimensions of 4¼” high x 6” long x 0.016” thick. As of October 2023, the mailing cost of postcards is $0.51.

Large Envelopes or Small Packages

When your mailpieces do not meet the USPS standard letter size criteria, they are categorized as either large envelopes or small packages. These mail items are allowed to have a maximum weight of 13 ounces, and their postal rates vary, ranging from $1.35 to $4.23.

Postage for Square Envelopes

Square envelopes, commonly used for special events, often incur additional postage costs. The rates for stamps on square, oversized, or uniquely shaped envelopes start at $1.06.

Odd-size/Nonmachineable Letters

Any letter or card that doesn’t fit the standard postal dimensions may be considered nonmachinable and subject to extra postage. This includes square, rigid, and irregularly shaped envelopes.

Custom Postage Stamps for Square Letters

Custom postage stamps could add a personal touch to your mail. However, these stamps should still adhere to the standard postage rates, even when used on square or nonmachinable letters.

When Should You Mail Your Wedding Invitations?

Timing is crucial when it comes to mailing wedding invitations. To ensure your invites reach your guests on time, sending them approximately six to eight weeks before the wedding day is recommended. 

An invitation must conform to specific requirements to qualify for First-Class Mail postcard pricing.

First, it should have a rectangular shape. Additionally, it needs to meet certain size parameters, with a minimum size of 3 ½ inches in height, 5 inches in length, and a thickness of 0.007 inches.

On the other hand, it must not exceed a maximum size of 4 ¼ inches in height, 6 inches in length, and a thickness of 0.016 inches.

 If your mailpiece fails to satisfy these prescribed dimensions, it will be classified by the Postal Service as a letter, and you will be charged postage at the letter-size rate.

To Be Eligible for Mailing at the Price For Letters, a Piece Must Be

Certain criteria must be met to qualify for mailing at the standard letter rate. 

The letter must have a rectangular shape and fall within specific dimensions: it should be at least 3½ inches high by 5 inches long and have a minimum thickness of 0.007 inches. 

Additionally, it should not exceed 6⅛ inches in height by 11½ inches in length and should have a maximum thickness of ¼ inch. If your letters fail these prerequisites, they’ll incur a $0.40 (as of 2023) non-machinable surcharge.

Hand-Canceled Invitations

Sometimes, hand-canceling your invitations can be a wise choice. It involves a postal worker stamping the mail by hand instead of a machine.

Your postal clerk will mark each postage stamp on each envelope with a special rubber stamp noting the current date and the postal location.

Consider Hand-canceling Your Beautiful Invitations if They …

Suppose your invitation cards are adorned with embellishments or have nonstandard dimensions. In that case, hand-canceling helps prevent damage to the cards.

How Many Stamps Do I Need? And Where to Buy?

For standard-sized letters weighing 3 ½ ounces or less, one stamp suffices. Larger envelopes require two stamps for the first ounce, with an additional charge for each extra ounce.

International mail can be handled with Forever stamps or Global Forever stamps. For letters weighing one ounce or less, one Global Forever stamp or three Forever stamps will suffice.

The U.S. Postal Service has its own online store for buying stamps; you can purchase as many. Alternatively, you’ll find other online sellers like Stamps.com, where you can buy stamps and print postage from home.

If you prefer not to buy online, you can visit your nearby post office to purchase stamps. There’s also the option to buy stamps by phone at 1-800-STAMP-24.

What Are Forever Stamps?

Forever stamps were created by the U.S. Postal Service in 2007. These stamps are nondenominational First-Class postage that can be used for First Class Mail regardless of the postal rate changes. 

For instance, people who purchased Forever stamps three years ago can still use them today to mail letters without requiring additional postage, even if rates have increased.

How Many Forever Stamps Do I Need?

To calculate the number of Forever stamps you need, consider the weight and size of your mail.

A single Forever stamp covers the postage for a 1oz letter. For every ounce in weight for your letter or envelope, just add an extra stamp to ensure you have the right amount of postage.

How Do Forever Stamps Work?

As their name implies, Forever stamps can be applied to send a one-ounce letter, irrespective of the purchase date or any potential future price adjustments.

Forever stamps provide a convenient way to mail standard-sized letters at the current First-Class rate. You can use multiple Forever stamps for heavier letters or packages.

Can I Use Two Forever Stamps for Extra Postage?

For any domestic mail item exceeding one ounce in weight, it is necessary to supplement your Forever stamp with extra postage to guarantee USPS delivery.

Alternatively, you can acquire postage stamps with higher denominations from the Post Office.

Each Forever stamp is equivalent to the current First-Class rate, so by using two stamps, you can meet the postage requirements for a piece valued at double the standard postage rate.

How Many Stamps in a Book?

The standard stamp book for First-Class mail postage comes with 20 First-Class stamps that can be applied to envelopes and on First-Class postage.

How Do I Know How Much Vintage Postage I Need?

Using vintage postage stamps (classic stamps that are no longer in circulation) can add a touch of nostalgia to your mail. 

To determine how much vintage postage you need, weigh your mail and calculate the required postage based on current rates.

You can visit the post office to have your invitation weighed and measured, or alternatively, you can utilize the USPS Postage Calculator to obtain a reliable estimate.

How Much Is a Postage Stamp?

The United States Postal Service (USPS) informed the Postal Regulatory Commission (PRC) that postage prices would increase in January 2024. 

USPS has announced that it’s increasing the price of a First-Class Mail Forever stamp to $0.68, previously $0.66.

Pending a positive review by the Commission, the proposed adjustments would result in an approximate 2% increase in prices for mailing services products.

The planned Mailing Services price changes include the following:

ProductCurrent PricesPlanned Prices
First-Class Mail Letters (1oz)$0.66$0.68
First-Class Mail Letters (metered 1oz)$0.63$0.64
First-Class Mail Postcard$0.51$0.53
Single-piece First-Class Mail Letter and Flat, additional ounce$0.24No change
International Postcards and Letters (1oz)$1.50$1.55

The additional-ounce price for single-piece letters and flats will remain unchanged at 24 cents.


  1. USPS postage rates
  2. First-Class Mail
  3. Forever Stamp Fact Sheet
  4. Postage Stamps – The Basics
  5. International Mail & Shipping Services
  6. First-Class Mail International
  7. Domestic Mail & Shipping Services
  8. What is the Non-Machinable Surcharge for First-Class Mail®?
  9. First-Class Mail Fact Sheet
  10. Sizes for Large Envelopes and Flats