Our study aims to determine optimal sizing of below-the-knee (BTK) artery angioplasty without intravascular ultrasound (IVUS), compensating for conventional angiography underestimation by selecting a balloon size one size larger than the 1-to-1 angiographic sizing. Our study is a retrospective, single-center study. Patients were separated into 2 groups as over and angiographic reference group which the over group is larger balloon diameter selection (0.5-mm larger balloon diameter selection), and angiographic reference group is 1-to-1 balloon diameter selection by angiographic images. Primary end point was the target vessel reocclusion, whereas major and minor amputation was the secondary end point. Eighty-four patients with occluded BTK lesions treated with balloon angioplasty (Opt=43, Over=41). Primary patency was 62.8% at 12 months in angiographic reference group and 82.9% in over group (p=0.039). Amputation rate at 1-year follow-up was 9.8% in angiographic reference group and 16.3% in over group (p=0.382). TLR rate is 4.9% in over group versus 20.9% in angiographic reference group (20.9%) at 1-year follow-up (p=0.029). Our study demonstrates that oversizing the balloon diameter by one size larger in BTK artery angioplasty, guided by conventional angiography, results in a higher patency rate and a lower target lesion revascularization (TLR) rate, while amputation rate remains statistically similar between the 2 groups. Our study highlights the importance of compensating for conventional angiography's underestimation in BTK artery angioplasty by using a balloon size one size larger than the 1-to-1 angiographic sizing. Our findings demonstrate that oversizing the balloon leads to significantly higher patency rates and lower TLR rates, with no increase in amputation risk. This approach provides a practical, cost-effective solution for clinicians performing angioplasty without IVUS, allowing for better vessel treatment and outcomes in patients with chronic limb-threatening ischemia. Clinicians can implement this strategy to optimize long-term results in BTK interventions.