How to Compute USPS Postage Rates

Figure the cost to mail packages online.

Figure the cost to mail packages online.

So, you're mailing a present, package or something you sold online. You know it requires more than just a few stamps, but aren't sure how much the postage will cost. Happily, you can find out how much postage you need without leaving your home or office or standing in line at the post office. Make the calculation on the United States Postal Service (USPS)'s website. The postal rates are calculated by where you're sending your package, how fast you want it delivered, and the size or weight of your package. The Postal Service gives flat rates if you can't weigh your package, as well as rates by the pound or ounce if you have a scale.

Figuring Postage Without Scale

Go to the United States Postal Service home page ( Select "Calculate a Price" under the "Quick Tools" or from the "Ship a Package" menu; you will find the "Postage Price Calculator."

Choose "United States (Domestic Mail)" from "Select a Destination" if you are sending mail within the United States. If your destination is a foreign country, scroll down to find the country. Enter the recipient's zip code; if you don't know the code, click on "Zip Code Look Up" and type the address. For international mail, you will be sent to the International Price Calculator page; you do not need a zip code.

Type the date you plan to mail your package in the "Enter Mailing" box, and scroll to select the time you are putting the package in the mail.

Select the desired box or envelope under "Flat Rate Service" if you don't know the weight of your package or can't weigh it. Decide whether you want to send the package by Express Mail or Priority Mail. Count on one to two days delivery for Express Mail; on average, Priority Mail takes one to three days to reach its destination. The size of your box or envelope (not the weight) and speed of delivery determines the rate; you'll pay more postage for larger boxes or envelopes, and more for Express Mail than Priority Mail.

Click "Continue" at the bottom to get the price of your delivery, the date you chose to put it in the mail, and when it will arrive at its destination.

Figuring Postage with Scale

Set the scale to zero weight. Make sure the display reads "0.0" or "0"; if not, press the "TARE" button to display "0." Calibrate the scale if needed. Choose the pounds and ounces (lb/oz) as your unit of measurement.

Get the envelope or box you plan to do your mailing in (letter, large envelope, package, large package). To weigh an item with its package, put the empty envelope or box on the scale, press "TARE" and place the objects you are mailing in the container. To weigh just the item, touch the "TARE" button for "0" weight and place the item to be mailed on the scale.

Navigate to the "Calculate a Price" page on the United States Postal Service website. Enter the country of destination, the zip code if you are mailing within the United States, and when you are mailing the item.

Select the shape of your package under "Select Shape"; don't choose from the "Flat Rate" packages. Type in the exact pounds and ounces as shown on your scale. Click "Enter" to get your postage rate.


  • Purchase a digital scale if you intend to mail packages regularly; go with a mechanical scale if you only mail packages occasionally. Digital scales offer more accuracy and less trouble than mechanical scales, which require you to read a needle to get the weight.
  • Some scales automatically calculate the postage rate. If you have a rate wheel, turn the dial to the weight and look for the postage corresponding with the weight. Some digital scales have been programmed with current postage rates. These scales calculate the exact amount of postage based on the weight of your package.


  • If you are calculating and printing postage with a postal meter, use only those authorized by the United States Postal Service. Find authorized postal meter providers from the Postal Service's postal meter page (see Resources).
  • Keep cell phones and other wireless devices away from the scales. These devices might interfere with your scale, cause the weight to display wrong and require you to recalibrate the scale.

About the Author

Christopher Raines enjoys sharing his knowledge of business, financial matters and the law. He earned his business administration and law degrees from the University of North Carolina at Chapel Hill. As a lawyer since August 1996, Raines has handled cases involving business, consumer and other areas of the law.

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