how big is a standard envelope
In a Variety of Sizes and Colors. Regular Envelopes come in a wide range of sizes, colors, and styles. They typically feature a solid front with no window, and a basic flap on the back. Nearly all businesses need #10 envelopes, which measure 4 1/8 by 9 1/2 and hold a standard sheet of paper folded in thirds. Popoular uses for these envelopes to send invoices, checks, letters, and other types of mailings.