The height of a 1-year-old mango tree can vary depending on multiple factors, including the specific mango variety, growing conditions, and cultural practices. On average, a 1-year-old mango tree can range from around 2 to 4 feet (60 to 120 centimeters) in height. However, it's important to remember that individual tree growth can vary, and factors like pruning and fertilizer application can influence the size of a 1-year-old mango tree.