Overnight mail usually costs about $30 to $80+ , depending on the carrier, package size, weight, and destination. For a standard overnight letter, USPS Priority Mail Express starts at about $33.25 retail, and many services include tracking and delivery guarantees.

How many stamps

A single stamp is not enough for true overnight mail. Overnight service is typically purchased as a postage label or shipping service, not by putting regular stamps on the envelope.

Quick options

  • USPS Priority Mail Express: around $33.25 for a flat-rate envelope.
  • UPS Next Day Air: starts around $41.37.
  • FedEx overnight services: start around $32.15 and can go much higher.

What to use

If you just need a letter delivered fast, the easiest choice is usually USPS Priority Mail Express. If you are asking how many stamps to use, the answer is usually none for overnight delivery because it needs special postage.

TL;DR: Overnight mail is usually around $30–$80+ , and it generally takes special postage instead of regular stamps.