
The US Mail weight chart is a crucial tool for determining shipping costs, and it's essential to understand how it works to avoid overpaying for postage.
The chart categorizes packages based on their weight and dimensions, with different weight ranges and corresponding postage rates.
For example, a package weighing 1 ounce or less is considered a lightweight package and is charged a lower postage rate, which is $0.55.
To give you a better idea, a 1-ounce package measuring 6.125 inches long, 3.5 inches wide, and 5.5 inches high is also charged $0.55 in postage.
Domestic Shipping
Domestic Shipping is a breeze with the US Postal Service (USPS). The cost to mail a standard first-class letter within the U.S. is 58 cents with a Domestic Forever Stamp, which offers delivery within 1-3 business days.
You can calculate the postage for letters over one ounce by adding 20 cents for each additional ounce. For example, a letter weighing 2 ounces costs 78 cents, and a letter weighing 3 ounces costs 88 cents.

If your envelope weighs more than 3.5 ounces, you'll need to look at rates for "flats", which are large envelopes for mailings from 3.5-13 ounces.
Here's a quick rundown of the postage costs for letters up to 3.5 ounces:
- 1 ounce: 58 cents
- 2 ounces: 78 cents (1 Domestic Forever Stamp + 1 additional ounce stamp at 20 cents)
- 3 ounces: 88 cents (1 Domestic Forever Stamp + 2 additional ounce stamps at 20 cents each)
- 3.5 ounces: $1.08 (1 Domestic Forever Stamp, 1 Postcard Stamp, and 1 10-cent stamp)
Keep in mind that the USPS offers a postage calculator to determine the cheapest combination of stamps for a letter or package.
Shipping Costs
Shipping costs can be a real headache, but with the right tools and knowledge, you can save yourself a lot of stress and money.
Calculating postage for parcels is much more complicated than calculating the cost of domestic letters. You need to factor in the weight and size of the parcel and the distance it is being mailed.
There are two ways to calculate how many stamps you need: using the stamp cost guide or the USPS postage calculator.
The USPS offers a postage calculator that can help you determine the cheapest combination of stamps for a letter or package. However, if you're sending a standard-sized package, you can use the USPS postage calculator to get the most accurate estimate.
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If your package is oversized, you'll need to use the DIM weight formula: H x W x D/166 = DIM weight. For example, if your box is 24” x 12” x 6”, the total is 1,728, which means you'll be charged the DIM weight of 11 pounds instead of the actual weight of 2 pounds.
To avoid DIM weight pricing, consider dividing your shipment into smaller boxes or using the smallest possible box to ship your items. At Red Stag Fulfillment, we've developed innovative ways to pack and ship orders in the smallest possible box, reducing shipping costs for our clients.
To save on oversized USPS shipping, you can also use the USPS flat rate shipping option, which charges a fixed price regardless of the weight of the package. However, this option only applies to packages that fit into a flat rate box or envelope.
Here are some tips to help you get discounted rates on your USPS shipping:
- Presorting your mailers allows you to get discounted rates because it helps the postal employees process the items faster and save time.
- Intelligent Mail Barcodes (IMBs) can help you track your items and get postal discounts.
- Verifying and standardizing your mailing lists before every campaign can also help you cut postage costs.
- Using ZIP+4 codes can help you reduce postage rates and ensure fast and accurate deliveries.
Shipping Options
When shipping packages, you have several options to choose from, depending on the weight and size of your item.
The United States Postal Service (USPS) offers various shipping options, including First Class Package Service, Priority Mail, and Priority Mail Express.
First Class Package Service is ideal for lightweight packages weighing up to 13 ounces.
Priority Mail is a good choice for packages weighing up to 70 pounds and offers a range of services, including tracking and insurance.
Priority Mail Express is the fastest option, with delivery times of 1-3 business days, and is suitable for packages weighing up to 70 pounds.
The cost of shipping will depend on the weight and size of your package, as well as the shipping option you choose.
Consider reading: Legal Tractor Trailer Weight
Envelope Weight and Size
The standard envelope weight is a crucial factor in determining the postage cost of your mail. Most people use #10 or #20 envelopes for their mail, but the maximum weight limit for large letters is 13 oz.

A standard envelope weighs 6.75 g when empty, but the total weight of an envelope would be nearly 11.25 g when you add a single-page letter. The size of a standard envelope is usually 4.125” x 9.5”, but it can vary slightly.
You can choose from various envelope options, including #9, #10, 6×9, and 9×12 envelopes, each with its own weight and size. The weight of an envelope is measured in pounds, with #9 envelopes weighing around 20# to 24#.
The maximum size limit for large letters is 15” x 12” x 0.75”, and they must be rectangular to qualify for standard First-Class Mail rates. You can use Forever stamps to ship First-Class Mail items, but you only need one stamp to send a 1 oz letter or postcard.
Here are some common envelope weights and their corresponding sizes:
Keep in mind that the weight limit for large envelopes and packages is up to 13 oz, making First-Class Mail ideal for regular shipping. However, the weight limit for standard letters is 3.5 oz, so be sure to measure your envelopes after stuffing them to get the accurate weight for postage.
Calculating Shipping Charges

Calculating shipping charges can be a daunting task, but it's essential to get it right to avoid unexpected costs. The USPS offers various tools and tables on its website to help you determine the postage costs for your mailpieces.
To get discounted rates, presorting your mailers is a good idea. Presorting allows you to get discounted rates because it helps the postal employees process the items faster and save time. However, it can be time-consuming and daunting, causing many businesses to skip the process.
Intelligent Mail Barcodes (IMBs) can also help you get postal discounts. Adding IMBs to your items lets you track them as they move through the USPS network. This not only helps you get discounts but also allows you to track your mailpieces.
Address verification and standardization are another way to cut postage costs. You can use PostGrid's direct mailing solutions to ship to validated and standardized addresses and prevent mail returns and the need to reship the items, saving money.

Using ZIP+4 codes can also help reduce postage rates. ZIP+4 codes allow postal workers to route your mailers for fast and accurate deliveries.
Here's a summary of the postage costs for different types of mailpieces:
Note that these rates are subject to change and may vary depending on the specific mailpiece and shipping method. It's always best to check the USPS website for the most up-to-date information.
To save nearly 39c on the first ounce, you can fold flat-sized letters or cards into letters of standard sizes. However, ensure the weight does not exceed the USPS standard envelope weight.
Envelope Materials
Envelope materials play a crucial role in determining the durability and appearance of your mailpieces. You can choose from various types of paper stocks to suit your mailing objectives and budget.
Wove paper is one of the most economical options for printing envelopes of average letter weight and size. It has a smooth finish and is available in several colors and weights.

Surfaced Enhanced White Wove is a popular choice for mailing items using the standard weight of a letter or envelope. These envelopes are available in typical 20# to 20# paper weights, suitable for heavy ink artwork.
Kraft paper is sturdy and has long fibers, making it ideal for sending compliance and transactional documents. It's usually brown in color and suitable for heavier envelope weights.
You can also opt for recycled envelopes to improve sustainability, especially if you mail large volumes of letters. They're available in several envelope weight options and sizes to suit your requirements and budget.
Specialty envelopes are available in various textures, colors, types, finishes, sizes, and weights. They're best for direct mail marketing but come with a higher price tag.
Tear-resistant envelopes are perfect for sending crucial mailpieces. They have an indestructible cover that's often moisture and water-resistant, ensuring your documents arrive safely.
Here are the six primary paper-grade types for envelope production:
- Wove
- Surfaced Enhanced White Wove
- Kraft
- Recycled
- Specialty
- Tear-resistant
Weight and Postage

The weight and postage of your mail can be a bit tricky to understand, but it's essential to get it right to avoid any issues with your mailpieces. For example, the maximum weight limit for large letters is 13 oz, and if your item weighs more than that, it's considered a parcel and may need to be sent via Priority Mail or Express shipping services.
The size of your mailpiece also matters, as large envelopes and packages have a maximum size limit of 15” x 12” x 0.75”. If your item is larger than that, you'll need to pay surcharges, which can increase your total shipping costs. On the other hand, if your item is small enough, you can use Forever stamps to ship it via First-Class Mail, which starts at $0.60 for a 1 oz letter.
To calculate your postage costs, you can use the USPS tools and tables on their website. However, you can also get discounts by presorting your mail, using Intelligent Mail Barcodes, and verifying your mailing lists. For example, using ZIP+4 codes can help postal workers route your mailers for fast and accurate deliveries, which can reduce postage rates. Here is a list of postage costs for letters over one ounce with Domestic Forever Stamps:
Shipping

Shipping can be a complex and costly process, especially when it comes to oversized or heavy items. USPS charges are always the greater of the actual weight or dimensional weight.
To calculate USPS dimensional weight charges, you can use the formula: H x W x D/166 = DIM weight. For example, if you have a box that measures 24” x 12” x 6”, the dimensional weight would be 1,728 cubic inches, making it subject to DIM weight pricing.
Presorting your mailers can help you get discounted rates, as it allows postal employees to process items faster and save time. USPS recommends presorting for commercial and large-scale mailings.
To avoid dimensional weight pricing, you can consider shipping items in smaller boxes. For instance, if you have a 2-pound item, you could divide it into two smaller boxes, each under 1 cubic foot, which might cost less to ship than a single large box.

USPS offers tools and tables on its website to inform you of postage costs. You can also use ZIP+4 codes to help postal workers route your mailers for fast and accurate deliveries, which can also reduce postage rates.
If your package falls into the category of being over 1 cubic foot in total area, you'll be subject to DIM weight pricing. To figure this out, multiply height x width x depth, and if your total equals or exceeds 1,728 inches, you'll be subject to DIM weight pricing.
Here are some strategies to save on oversized USPS shipping:
- Divide your shipment into smaller boxes
- Use the smallest possible box to ship your items
- Use infill to fill empty spaces in the box, making sure to use the smallest amount necessary
At Red Stag Fulfillment, we have experience shipping heavy items, including arcade games, bicycles, furniture, and more. We've come up with innovative ways to reduce the cost of shipping for our clients.
Weight of a Letter for One Stamp
A letter weighs 1 oz for one stamp, which means even an envelope of less than 1 oz comes in the same category. This is the lowest weight that USPS considers and charges for.

You can fit between one and six lightweight paper sheets in a 1 oz envelope, making it ideal for mailing single-paged and multiple-paged documents. This is why it's a popular choice for everyday mail.
To calculate the number of stamps for letters, you simply need to know the weight of the envelope. A 1 oz envelope needs one postage stamp, a 2 oz envelope needs two, and so on. You can also use cent stamps if the weight of an envelope falls somewhere in between.
If you're shipping flats via First-Class Mail, the cost starts at $1.20, and for packages, it begins at $4.50. However, these rates apply if you follow USPS guidelines to prepare your mailpieces. Any deviations can result in you paying more, which can hamper the cost-effectiveness of First-Class Mail.
Here's a quick reference guide to help you calculate postage costs:
Remember, these rates and calculations are based on the current USPS rates and may change over time. Always check the USPS website for the most up-to-date information.
Sources
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