If your business occasionally mails light packages using USPS First-Class Mail, you can consider using the regular postal stamps that you already have handy for sending letters. Unlike when you are using electronic postage, you'll get no tracking number when using stamps to mail a package, but you do get the convenience of not needing to print shipping labels. You'll need to follow USPS guidelines for stamped mail, properly calculate your postage rate and use the right combination of stamps to avoid insufficient postage issues.

Using Stamps for USPS Packages

You can use regular USPS First-Class postage stamps to mail domestic packages weighing no more than 13 ounces. Such packages must follow the maximum sizing rules. This means that when you combine the length and girth (height times two plus width times two) of the package, it must equal no more than 108 inches.

The cost of mailing a USPS First-Class package depends on the weight and postal zone. Currently, you can pay as little as $3.80 to send a package weighing 1 to 4 ounces to as much as $6.50 to send a 13-ounce package. You can purchase Forever Stamps worth 55 cents in First-Class postage as well as less-expensive partial stamps in denominations ranging from 1 cent to 15 cents. You can also buy more expensive stamps ranging from 65 cents to $10.00.

You'll need to use a combination of these to have the proper postage for your USPS First-Class package. If you only have a certain type of stamp available, you could end up overpaying for your package.

Trying the USPS Shipping Calculator

If you know the postal zone and package weight, you can access the USPS rate charts online to find the postage cost. To avoid the problems that happen when you don't attach enough stamps to your package, USPS recommends using its shipping calculator to get an accurate price.

To access the calculator, go to the USPS website and select "Calculate a Price" from the "Quick Tools" menu. You'll plug in the Zip Codes for both the destination and mailing location and then select the option to calculate the price using the shape and size of the package.

Enter the weight of the package and select the "Package" or "Large Package" option depending on your package size. USPS may ask for you to type the specific dimensions before displaying a pricing list, where you can locate the First-Class price.

Determining the Stamps Needed

Using the given price from the USPS shipping calculator, locate your stamps and stick on a combination that will at least reach the listed postage cost. If you're using Forever Stamps, keep in mind that you can use partial stamps to make up any difference without needing to use another large stamp.

For example, consider that the calculator gave you a rate of $4.60 to mail a package, and you just have Forever Stamps worth 55 cents each. In that case, you could divide $4.60 by 55 cents to get around 8.4 stamps. Unless you can obtain some partial stamps, you'd need to round up and stick nine Forever Stamps ($4.95) on your package to successfully mail it.

Alternatively, you could use eight Forever Stamps ($4.40) plus two partial stamps worth 10 cents each to avoid paying for excessive postage. You can buy both regular and partial stamps from your post office or the USPS website.

Shipping Your Package With Stamps

Before you try to drop your package in a USPS mailbox, know that the postal service has some rules about mailing packages using just stamps. Currently, you'll need to give your package to a postal worker at a local post office if the weight is over 10 ounces or if the thickness exceeds half an inch. This allows the postal worker to verify you've included enough postage.

For other USPS First-Class packages, you can schedule a pickup or drop them in a USPS mailbox without visiting a post office. However, keep in mind that USPS can still return parcels without sufficient stamps, which could cause shipping delays. Therefore, double check the stamps used against the calculated postage price.