For a 9x6 manila envelope, postage usually depends on weight and whether it qualifies as a large envelope (flat) or a letter. Based on USPS size rules, a 9x6 manila envelope is generally treated as a large envelope if it’s thicker than 1/4 inch or otherwise doesn’t fit letter-mail requirements, and large envelopes start at $1.63 for the first ounce.

Typical postage

  • If it is thin, flexible, and under 1/4 inch thick , it may mail as a letter, starting at $0.78 for up to 1 ounce.
  • If it is treated as a large envelope (flat) , postage starts at $1.63 for up to 1 ounce.
  • Additional ounces add more postage, so heavier envelopes cost more.

Practical rule

A 9x6 manila envelope is often mailed like this:

  1. Under 1 oz and letter-eligible: 1 Forever stamp may be enough.
  1. Flat/large envelope: expect at least $1.63.
  1. If it’s rigid, bulky, or has clasps , it may be treated differently and cost more.

Best estimate

If you just want the most likely answer for a typical 9x6 manila envelope, plan on about $1.63 or more unless it is very thin and qualifies as a letter.

USPS rules can change, so the exact amount depends on the envelope’s weight and thickness.

TL;DR

A 9x6 manila envelope is usually $1.63+ if mailed as a flat, or $0.78 if it qualifies as a standard letter and weighs 1 oz or less.