Your answer depends on the origin location of the letter and its ultimate destination. If your point of origin is in the United States, you can review USPS postal rates, below.
Otherwise, you can find local postal rates at your local post office.
2
how many first class stamps does it take to mail a 4 oz letter and package
78 cents
1 oz letter to UK is .94
-2 and 1/2
what stamp amount is needed if the letter is 15 oz.?
3 it is 1 stamp/ounce as a rule of thumb
2 stamps. ! stamp is good for up to one ounce, 21 cents for second ounce.
You need one 44 cent stamp for a letter up to 1 oz. You can use any number of stamps as long as the postage total is 44 cents.
The number of stamps needed for 2.2 oz postage depends on the weight and the type of stamps you are using. For standard First-Class Mail in the U.S., a letter weighing up to 1 oz requires one stamp, and each additional ounce typically requires an extra stamp or additional postage. Therefore, for a 2.2 oz letter, you would generally need two stamps, potentially adding more if they are lower denomination stamps. It's best to check the current postage rates for the most accurate calculation.
36 fl oz is 1064.65mL
One forever stamps pays for up to a one ounce letter. BTW, I think .06 oz. is impossibly light. Maybe you meant .6 or something else.