Most flat rectangular greeting cards can be mailed for the standard letter rate within the United States (or using a “forever” stamp) as long as they have a uniform thickness of under 0.25 inches and weigh under one ounce.

As of July 2024, the current rate to mail 1-ounce first-class letters is $0.73 or a “forever” first-class letter stamp purchased at any time. Note that although the post office refers to this rate using the word “letter” frequently, a greeting card is typically still eligible for this rate assuming it meets the requirements outlined here.

Some greeting cards may be heavier than one ounce or end up being an uneven thickness.

As a rule of thumb, a 1 ounce letter is about four sheets of standard printer paper plus an envelope. Greeting cards tend to be made using heavier paper stock, meaning they weigh more, so a general guideline is that a greeting card with one small insert such as a gift card, a single piece of paper currency or small note will also be about that weight.

Each additional ounce of postage costs $0.28.

Some cards may require extra postage

Some heavier, more complex cards mailed by themselves may require extra postage, while mailing a card with an item such as gift card, letter or other enclosure can increase the weight as well.

Please note that adding additional items to the inside of a card can increase the weight or thickness of your envelope beyond the base first-class rate. Such items can include gift cards, cash, letters or other small items.

Mailing thicker or heavier cards

To be certain you’re calculating postage correctly, you’ll also need to know the weight of the item, including the envelope. There are postage scales that weigh in ounces that can be helpful if you mail cards frequently. These are available for purchase online.

That said, the most accurate way to ensure you have the exact postage needed is to take your item to the post office. Be sure it’s sealed and ready to send. Ask an employee at the counter to weigh it and offer postage options.

In many cases, postage purchased at postal service counters is printed on a white label that will be stuck to your envelope, which can sometimes make your envelope look less aesthetically-pleasing. On smaller envelopes or envelopes with a lot of text or designs, the label can often cover part of these elements as well.

The USPS considered the term “uniformly thick” to mean that any variance in thickness does not exceed 0.25 inches. This common with cards that contain layered items that “stick out” from the surface of the card. Thicker cards in 3D frames, pop-up cards or cards with other 3D elements may exceed the 0.25 inch variance.

If you don’t want to go to the post office, there is one option that you can try.

First, you’ll need to stock up on “forever” and “additional ounce” stamps. As of 2024, “forever” stamps cost $0.73 each and “additional ounce” stamps are $0.28 each.

If your card feels thicker and at least uniformly thick, you can try using one “forever” stamp and one (or in rarer cases two) “additional ounce” stamp or stamps. The post office won’t refund anything if your card is not actually heavier than one once, but simply paying an extra $0.28 or so can sometimes be worth the hassle of going to the post office.

This tip won’t always work, but it’s been found to be effective across thousands of cards with only a very small percentage flagged for incorrect postage.

It’s important to note that this tip will not work if your card is considered nonmachineable, as outlined in the next section.

Nonmachineble mail

The USPS considered mail that meets any of these characteristics to be “nonmachineable”:

• It is a non-rectangular shape (most often a square)
• It has an uneven thickness that varies more than 0.25 inches
• It is thicker than 0.25 inches (anything thicker than this may be considered a package or flat)
• It is heavier than 3.5 ounces (anything heavier than this is considered a package)
• It is smaller than 3.5 inches by 5 inches (anything smaller than this cannot be mailed as a letter)
• It is larger than 11.5 inches by 6.125 inches
• It is thinner than 0.007 inches (not common)
• It does not bend easily
• It has rounded corners of more than 0.125 inches in radius
• It has prongs, strings or other unique closures

The U.S. Postal Service calls items that fit in this criteria as “nonmachinable,” because they cannot be processed on the standard sorting machines used to process mail. Because these items have to be routed differently, there is a higher cost of processing them.

As of July 2024, most nonmachineable items cost $1.19 between $1.75 to mail. This is the $0.73 base rate plus a surcharge.

• Items up to 1 ounce: $1.19
• Items up to 2 ounces: $1.47
• Items up to 3 ounces: $1.75

Getting the right postage

Getting to the correct amount of postage can be tricky, but can be accomplished by combining stamps with different values.

There are stamps available at $0.01, $0.02, $0.03, $0.04, $0.5 and $0.10 denominations.

Technically speaking, the postal service only looks at the monetary value of the stamp, not the name of the stamp. Because of this, you can use additional ounce stamps to get to the value needed to mail your item and, as long as the total adds up to that amount or more, it should be accepted.

Because of this, you can combine two or more stamps to get the required postage amount.

• For nonmachineable mail up to 1 ounce, you can use 1 first-class forever letter stamp plus 2 “additional ounce” stamps ($0.73 + $0.28 + $0.28 = $1.29, which is $0.10 more than the actual cost).
• For nonmachineable mail up to 2 ounces, you can use 2 first-class forever letter stamps plus 1 “additional ounce” stamp ($0.73 + $0.73 + $0.28 = $1.74, which is $0.27 more than required). Alternatively, use 2 first-class stamps plus 1 stamp worth $0.01 to get to the exact total or a combination of lower denomination stamps to get to the exact total.
• For nonmachineable mail up to 3 ounces, you can use 2 first-class forever letter stamps plus 2 “additional ounce” stamp ($0.73 + $0.73 + $0.28 + $0.28 = $2.02, which is $0.27 more than required). If you only have first-class letter stamps, you could use 3 of them to get to the amount you need or a combination of lower denomination stamps to get to the exact total.

The post office does not offer refunds for credits for “extra” postage you affix to envelopes. If you don’t want to waste the extra postage, you’d need to either buy stamps of smaller denominations or take it to a postal employee.

If you find yourself mailing non-standard cards frequently, it may be worth the investment of purchasing some stamps in $0.01 and $0.05 or other varieties to avoid paying extra frequently.

It’s important to remember that standard size envelopes (A2 or 4.375 inches by 5.75 inches) may not have enough room for two or more stamps. In these cases, you would need to purchase an “exact amount” postage label from the post office or your postage meter or software.

Insufficient postage

If the post office calculates that you did not include enough postage, the item may be routed back to the return address on the envelope (this is one reason it’s important to always include one on everything you mail).

In some cases, the item may be delivered to the recipient with a request for them to pay the extra postage, which is obviously not the best situation.

Hand canceling

For envelopes with designs or made from specialty paper, it can be better to have these items hand-canceled. This requires double the standard postage rate for first-class letters.

The best way to request hand-cancellation is to take your item to the customer service desk at the post office and hand it to an employee with your request. Some customers also have success with attaching a sticky note to the envelope with “Please hand cancel” on it, but this is not guaranteed.

How long it takes for cards to arrive

First-class letter and cards generally arrive in 1 to 5 business days but are not guaranteed. The distance the item has to travel is one factor in how long delivery can take, but other factors, such as weather, time of year, mailing to or from rural or geographically distant locations and other issues, may add to delivery time. First-class mail is not time definite, and there is compensation when an item is delivered beyond a certain number of days.

When to mail cards

In general, it’s a good idea to allow up to 7 business days for first-class mail to be delivered if it is important that it arrive by a certain date. Of course, there is always the chance the item will arrive early. Some people will write “Do not open until (date)” on the flap of the envelope.

During holiday seasons, mail can take longer, so it’s best to get cards ahead of the winter holidays, Mother’s Day, Father’s Day and Valentine’s Day out even a few days earlier.

Damaged mail

The U.S. Postal Service also does not guarantee that items will arrive intact. There are rare cases when mail gets caught in machinery and may become ripped, scuffed, stained or otherwise damaged. Customers are not compensated when items arrive damaged unless insurance is purchased separately.

In many of these cases, the post office will place the damaged mail in a plastic bag and deliver it with a note explaining the damage.

In some cases, sending “nonmachinable” mail can cut down on the likelihood of damage, but it’s still not guaranteed.

Return addresses

The USPS recommends that all mail have a return address (most commonly the sender’s address) in the upper left corner of the envelope. For smaller envelopes, you may need to write this address smaller to make it fit and avoid confusion with the recipient address.

An alternative is to print the return address on the back flap of the envelope. If you take those route, please be aware that in some rare cases, USPS equipment may confuse this as the recipient address and the card will be delivered to the return address. A good way to avoid this problem is to either keep the return address on the front, make sure it is as close to the top of the envelope as possible and keep the text size relatively small.