Whether money doubles in 7 years depends entirely on the compound annual growth rate (CAGR) applied to the principal investment. According to the Rule of 72, an investment must generate a steady annualized return of roughly 10.28% to double over a 7-year timeframe. If an investment vehicle earns lower average annual returns—such as traditional savings accounts or ultra-short treasury funds—it will take significantly longer than 7 years for the principal balance to double.