USPS First-Class Mail® made better
USPS First-Class Mail® is the affordable, everyday choice for postcards, letters, and large envelopes. Stamps.com makes it even easier—print postage online, access built-in discounts, and track delivery times, all without ever setting foot in the post office.
Save on postage, speed up delivery time, and simplify mailing services
Control postage rate spend, get dependable 1–5 business days delivery time, and avoid post office lines. With Stamps.com, you can print USPS First-Class Mail postage at home and save while you send postcards, letters, and flats.
Lower your cost to send First Class Mail
Save money by getting USPS’s best prices for class mail letters, class mail postcards, and flats up to the maximum weight for First Class Mail. Stamps.com adds online discounts so your postage rate stays low without extra trips to the Post Office for the cheapest way to send First-Class mail.
Reliable delivery time across the U.S.
Most USPS First-Class Mail arrives in 1–5 business days, ideal for invoices, statements, and everyday communications. Need proof of mailing information? Add Certified Mail for send-and-receive confirmation when it counts.
Simpler sending for everyday needs
From postcards to large envelopes, calculate postage costs in minutes, print, and hand off. Avoid non-machinable and unusually shaped designs to keep mailing costs and fees down. Compare carriers and rates for various types of mail and packages with your Stamps.com subscription.
Have a first class experience at every step
Learn what you can send, expected delivery times, size and weight limits, and popular add-ons—all while saving on every label with Stamps.com.
Send with certainty
First-Class Mail is ideal for postcards, letters, and large envelopes—perfect for everyday correspondence, bills, statements, greeting cards, and lightweight documents. To avoid surcharges, design your mail for easy sending, avoiding any unusually shaped or rigid mailpieces. Add optional services like Certified Mail® for tracking-style confirmation when needed.
Deliver in 1–5 business days
Plan on 1–5 business days for domestic delivery time. This makes First-Class Mail a smart choice for time-sensitive communications that don’t require package services. Add Certified Mail when you need proof of mailing and delivery.
Always know your exact price
Stop doing postage math—Stamps.com calculates the exact First-Class Mail® rate for every piece before you print. Whether you’re sending letters, postcards, or large envelopes, you’ll get the right rate automatically.
Size and weight rules—know the limits
Stay within USPS requirements to keep costs down. Letters can weigh up to 3.5 ounces, flats up to 13 ounces, and large envelopes up to 12 inches high, 15 inches long, and ¾ inch thick. Go beyond these limits and your mail qualifies as a package—often billed at USPS Ground Advantage® rates instead of First-Class Mail® letters or flats. Stay rectangular and evenly shaped to avoid nonmachinable surcharges.
Frequently asked questions about USPS First-Class Mail
How do I get started sending First Class Mail with Stamps.com?
Create your labels or print postage from any printer, weigh your piece, and drop it in any USPS collection box or schedule a pickup. If you are sending First Class Mail often, build saved presets for common piece types so you can send postcards, letters or flats in a few clicks.
What is the difference between letters, flats, and small packages?
Letters and flats are considered mail, while small packages are parcels. Letters are slim documents, flats are larger envelopes, and parcels include merchandise or thicker contents. If your item becomes too rigid or bulky, it will be treated as a parcel and priced differently than USPS First Class Mail.
Where does “class package service” fit today?
If you have seen references to class package service, that was historically First-Class Package Service. Today, comparable lightweight parcels ship under USPS Ground Advantage. Use Stamps.com to compare rates so you choose the right option for your shipment before sending First Class Mail.
Why does the maximum weight for First Class Mail flats and large envelopes matter?
Design and content choices add weight quickly. Knowing the maximum weight for First Class Mail flats large envelopes helps you choose paper stocks, inserts, and tabs that stay within limits and avoid a surprise shift to parcel pricing at checkout.
Can I send postcard letters with custom designs and still qualify for machinable pricing?
Yes. Keep pieces rectangular, evenly thick, and flexible. Place addresses and barcodes in recommended zones and avoid clasps or rigid elements. Following machinable guidelines lets you send postcards letters at the lowest postage for USPS First Class Mail.
What add-ons help when I need extra assurance without turning it into a parcel?
For important documents, consider Certified Mail or a Certificate of Mailing. These services provide proof of mailing or delivery while keeping your item in the letter or flat category, which is often more economical than moving to a parcel or small packages service.
Can I improve deliverability when I send high volumes of First-Class Mail?
Absolutely. Validate addresses before printing, use clear fonts, and keep return addresses consistent. For large campaigns, segment by geography and time your drops to match in-home windows, then track responses alongside mailing data inside Stamps.com.
How does Stamps.com help teams standardize sending First Class Mail?
Set up shared address books, user permissions, and cost codes. Use automation rules to apply the correct service based on weight and shape, then report on spend by department. This keeps every piece compliant and on budget across your organization.
What if my marketing insert makes a flat too thick at the last minute?
Weigh and measure again. If your flat crosses thickness or rigidity thresholds, repackage into a lightweight parcel and compare pricing. Stamps.com will show you parcel options alongside letter and flat pricing so you choose the most cost-effective path for USPS First Class Mail.
What makes an envelope nonmachinable?
Nonmachinable mail includes pieces that are rigid, uneven in thickness, non-rectangular, or sealed with materials other than paper. Keeping your mail flexible, flat, and rectangular helps you qualify for the lower USPS First-Class Mail® postage rate.
How can I save time and money on First-Class Mail?
Print exact postage from home or the office, skip the Post Office line, and save on eligible First-Class Mail® shipments. With Stamps.com®, you can efficiently manage postcards, letters, and flats—all while staying on budget.
How do I know how much postage to apply?
Have your mailpiece’s weight, shape, and size ready. Then use the USPS Price Calculator to find the correct rate for postcards, letters, or large envelopes. Once you know the amount, print accurate postage through Stamps.com® and mail with confidence.
When does my mailpiece qualify as a package instead of class mail?
If your large envelope weighs more than 13 ounces, is thicker than ¾ inch, or is too rigid or bulky, it will be treated as a small package and priced under USPS Ground Advantage® rather than First-Class Mail®.