How much should you invest for college? The answer depends on several factors, including a child’s age, type of college and percentage of total costs you plan to pay. The left chart shows how much new investors should start contributing each month. The right chart shows how much existing investors should either have accumulated today or contribute in one lump sum to be on pace toward goals. Key takeaway: Dollar amounts in both charts get bigger as children get older. The sooner you start, the less you may have to invest.