A bunch of basil equals 2.5 ounces, including stems. A bunch of basil leaves, without stems, yields 1.4 ounces. One bunch also equals approximately 3/4 to 1 cup of chopped basil. Commercially packaged fresh basil leaves are sold in 1/4-, 3/4-, 2- and 4-ounce packs.
When growing basil in the garden or in containers, one plant can produce up to 27 ounces of leaves during the growing season, depending on the variety grown and how often the plant is pruned. Most pesto recipes call for approximately 2 cups of fresh, packed leaves. Pesto, which is a popular Italian sauce made with fresh basil, olive oil, garlic, pine nuts and Italian cheeses, requires at least 2 cups of packed basil leaves.