Appropriate substitutes for a jelly-roll pan include a 9-inch square pan, an 8-inch by 3-inch springform pan or two 8-inch round pans. These substitutes are appropriate for up to 10 cups of batter.
Using a different pan often requires an adjustment to the recipe's baking time. If the batter spreads out more thinly in the alternate pan, less baking time is necessary. If the batter is thicker in the substitute pan, more baking time is required.
While a jelly-roll pan can stand in for a cookie sheet, the reverse is not true. Jelly-roll pans have sides that are 1-inch deep to contain a rising cake or roll, but cookie sheets often have only a small curved edge.