One fourth of an A4 sheet would fit in a C6 envelope. Or rather an A4 sheet folded in 1/2 then in 1/2 again. An A4 is a European size paper similar to our 8 1/2 x 11 inch sheets.
What is the standard-size large envelope?
The standard size business envelope is the number ten. The number ten envelope is open sided with a commercial style flap.
An envelope can never be too large for itself.
3 1/2" x 5" (inches) is the smallest legal mailing size for an envelope in the US.
The size of the envelope and forms both matters.
Depends on the type and size of the page and envelope.
4" by 9"
C6 or an aod
The number 10 envelope is the most widely used envelope these days. The size of the number 10 evelope is 4 1/8 by 9 1/2 inches. This common size is used by businesses for doing mass mailings.
It depends on tne weight of the envelope not the size.
It is not the size of the envelope that matters, it is the weight - it is probably best to have the package weighed at the Post Office to obtain the correct postage.