The main purpose is to propose a new method for approximating the average interest rate using an ordered weighted average. The ordered weighted average (OWA), generalized GOWA operator and interval numbers are studied to develop this method. Using average interest rate formulation combined with aggregations operators and interval numbers presented above is the proposed weighted average interest rate (OWAIR) operator. For mathematical application, the deposit interest rates of the countries with 2020 data on the World Bank website are carried out. Finally, it should be noted that changes in the maximum, minimum, and average values are considered in the use of training for each region, which can be helpful for investors’ decision-making.