There is not a set price based on the size of the envelope. The final amount of postage will depend on the weight, the destination of the envelope and the thickness and/or the rigidness of the parcel.
postage needed for A09 envelope
How much does it cost to send a padded envelope to canada weighing 9 ounces
The amount of stamps needed for an envelope is determined by weight. Weigh your a4 envelope and you will know how much postage is needed.
Domestic postage is $1.39 for an ordinary envelope of uniform thickness.
In the US, $1.56.
2.80
One
For a 6.5 ounce item it depends on the shape of the item being mailed. If it will fit in a padded envelope, postage and shipping will be under $4.00. If a box is needed pricing will start at around $6.00. The website for USPS provides the tools to answer these questions and confirm pricing.
99 cents in a standard envelope.
The answer will depend on where you are posting it to!
For the first ounce it will be 88 cents. There is an additional charge for the larger size. Each additional ounce is 17 cents.
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