The answer will depend on where you are posting it to!
One
An envelope with a height exceeding 6 and one-eighths inches, and any square envelope, is non-machinable. Therefore, the rate for first class US domestic postage is $.64.
In the United States to a destination within the United States as of December 2009, it would be 44 cents plus a 20 cent non-standard surcharge plus 17 cents for each ounce or fraction of an ounce over one ounce, up to 3.5 ounces. HIgher rates apply if the envelope is more than 1/4 inch thick or weighs over 3.5 ounces. So if the envelope is one ounce or less, the charge would be 64 cents. Hint: you can save the 20 cent surcharge by putting your envelope inside a standard rectangular-shaped envelope. Note: This answer was correct when it was written. Postage prices change almost every year.
The answer will depend on where you are posting from, where you are posting to and whether or not there are any special requirements.
It depends on which country you are in and where you want to post it to!
One
The cost for postage on the 9x11-inch envelope will vary depending on the weight. As of May 2014, the standard cost of a stamp is 49 cents in the United States.
How much postage is required for a 6x8 inch card? It weighs less than 1 ounce.
thirty-two cents
Go to the site below and click on the "Calculate Postage" tab.
A 6x8 inch padded envelope will require approximately $3.00 for up to 13 ounces. The USPS website offers the tools for all calculations based on weight and envelope dimensions
Depends all on the weight.
An envelope with a height exceeding 6 and one-eighths inches, and any square envelope, is non-machinable. Therefore, the rate for first class US domestic postage is $.64.
1st class letter price which is 46 cents as of Oct 2013
As of August 2012, first class US postage for a 6x9 3.5oz domestic letter is $1.05.
area of envelope = l Xb =8.5 X11 =93.5 inch^2
Different countries have different postage rates and, in order to give a sensible answer to your question, it might have been just a tiny bit helpful to know which country you were posting from! Without that information there cannot be any sensible answer.