This study discusses the determination of the probability of die at one-year age intervals from the 2010 US life table using the Kostaki Modified interpolation method which is then used in calculating term life insurance premiums. The proposed modification method of Kostaki is Kostaki modification method with 6-point Lagrange and Kostaki modification method with Heligman-Pollard. The selection of the best interpolation results between the two methods uses Mean of Absolute Error. The results showed that first; the interpolation result of the probability of die at the one-year age interval using the Kostaki Modification interpolation method with 6 points Lagrange is better than the interpolation result with the Heligman-Pollard modification, with the value of Mean of Absolute Error 0.001 and 0.006 respectively. Second; term life insurance premiums calculated using the one-year age-interval probability of Kostaki's Modification with 6-point Lagrange interpolation, differ significantly from the premiums calculated using the five-year age interval probability of die in the abridged life table. The premium calculated using the abridged life table is four times greater than the premium calculated using the interpolated results.