The USPS® assigns mail into different services, called “classes.” Each class of mail has its own features, service levels, postage prices and presort requirements. Here’s the breakdown of all the different mail classes:
Meant for letters or parcels up to 13 oz., this mail class provides reliable national delivery in an average of one to three days. Plus, prices remain the same regardless of how far the mail travels and include forwarding and return services. FirstClass Mail® is the most common class because it’s fast, easy and affordable.
This mail class provides delivery for letters or parcels up to 70 lbs. in one, two or three business days, depending on origin and destination. Saturday and residential delivery are included in the price at no extra charge, along with free USPS Tracking and up to $50 insurance. Unlike some other carriers, you won’t pay fuel surcharges for this service. Plus, supplies such as boxes and envelopes are available for free with Priority Mail service, including flat rate boxes and envelopes. Flat rate prices are fixed, regardless of what’s in the box, as long as the item fits without altering the box or envelope. You may remember the famous slogan, “If it fits, it ships.” This can be especially handy for small but heavy shipments, like auto parts or paperweights.
This service provides guaranteed overnight delivery 365 days a year, including Saturday and residential delivery at no extra charge. It’s the fastest option offered by the USPS, and includes free USPS Tracking and up to $100 of insurance. As with Priority Mail, you won’t pay fuel surcharges with Priority Mail Express, and it includes free supplies like regular and flat rate boxes and envelopes.
This mail class applies to bulk mailings of at least 200 pieces or 50 lbs. Mailings must be less than 16 oz. and of a promotional nature. Examples include: flyers, circulars, newsletters, bulletins, catalogs and other advertising materials, which can be in the form of letters, flats or small parcels. USPS Marketing Mail is for domestic mailings only.
For mailings up to 70 lbs. the Periodicals class of mail is designed for newspapers, magazines, and other periodical publications that are mail to a list of subscribers. These must be published at regular intervals and at least 4 times a year in the form of printed sheets, as well as meet specific standards for circulation, record keeping and advertising limits. You can even access lower postage rates for Nonprofit, Classroom, and Science-of-Agriculture Periodicals. Only those who have submitted a formal application and been accepted can access these privileges. You can check to see if you’re eligible and apply at USPS.com.
This matrix from the USPS can help you determine which class of mail is right for your needs: