Thoracodorsal artery perforator (TDAP) island flap is a safe and reliable method for breast reconstruction. TDAP propeller flap has been described as a modification of the conventional island technique that saves time and does not require microsurgical skills. However, a substantial portion of the propeller flap remains under the axilla and is not used for breast augmentation. The aim of this study is to identify the differences in the reaching distances between the propeller and island TDAP flaps. In five cadaveric specimens and 10 breast reconstruction patients, an initial propeller flap was harvested and rotated to the anterior thorax; the distance from the tip of the flap to the anterior midline was recorded as the "midline-reaching deficit;" the flap was then converted into a conventional island flap, and the new midline-reaching deficit was recorded. Differences between groups were compared with paired two-tailed t-tests (α=0.05). In the cadaveric specimens, the mean midline-reaching deficit was 4.8 ±2.4cm with the propeller TDAP and -0.6±2.0cm with the conventional island TDAP (P<0.001). In the clinical cases, the mean midline-reaching deficit was 8.1±1.0cm with the propeller TDAP and -0.3±1.1cm with the island TDAP (P<0.000000001). We observed that the midline-reaching deficit could be reduced by 7-9cm with the conventional island TDAP in comparison to the propeller TDAP. This should be considered when reconstructing the medial inner part of the breast.