In general, as we stack HTS tapes, such as Bi-2223, transport AC loss increases more than the single tape loss multiplied by the stacked number. That is due to the AC transport current effects of adjacent/neighboring tapes. To find a way to estimate the AC losses of stacked tapes, we fabricated single-, double- and triple-stacked Bi-2223 tapes, which are insulated between the tapes, and measured AC transport current losses in each case. The measured experimental data showed that the AC loss of stacked tapes could be expected using both the loss data of a single tape and the degraded critical current value of stacked tapes.