Anatomical atrial distortion during catheter mapping and ablation has not been elucidated in atrial fibrillation (AF) ablation. This study aimed to characterize the regional anatomical distortion in common ablation areas according to different contact forces (CFs) with radiofrequency and cryoballoon catheters.Ten patients underwent distortion mapping with low (5-10 g) and high CFs (10-30 g) at the pulmonary vein (PV) antra, left atrial (LA) roof line, mitral isthmus line, cavotricuspid isthmus line, and superior vena cava (SVC)-right atrial (RA) junction. Fifteen patients underwent distortion mapping with a 28-mm second-generation cryoballoon surrounded by a decapolar catheter at each PV antrum following creating the LA geometry. High CFs distorted the PV antra as compared to low CFs and the extent was greater at the anterior PV aspect, and the catheter was located more inside the PVs. The inflated cryballoon stretched the PV surface in the postero-superior direction in the upper PVs and posterior direction in the lower PVs. High CFs as compared to low CFs distorted the LA roof and cavotricuspid isthmus in the postero-inferior and inferior directions, respectively, but not the mitral isthmus line even with deflectable sheaths. High CFs distended the SVC-RA junction as compared to low CFs, and the extent was greatest at the lateral side and smallest at the antero-septal side.Human atria significantly distend during radiofrequency and cryoballoon ablation, and there are regional heterogeneities of the extent of the distortion. This information might aid operators in performing safe and effective AF ablation procedures.