What is the standard pour in a single mixer cocktail?

Generally, the standard pour for single mixer cocktails is 1.5 oz. A “neat” pour, which is a spirit served by itself in a tumbler, is 2 oz. The 2 oz pour also applies to most single-spirit cocktails ordered “on the rocks” (with ice) or "up” (stirred with ice to chill and dilute, then strained into a glass).