Nucleus-independent chemical shift (NICS) calculations were performed based on the optimized structures at the center of the macrocycle. The NICS values, which measure the magnetic shielding at the center of the aromatic/antiaromatic ring (positive values indicating stronger antiaromaticity), revealed that the antiaromaticity strength decreased (1e > 1d > 1a > 1b ≈ 1f > 1c), correlating with the magnitude of the tilt angle between the mesosubstituents and isophlorin macrocycles. Notably, 1d and 1e exhibited pronounced antiaromaticity, which is attributed to their completely planar isophlorin macrocycles. δ(Hβ) NICS(0) NICS(1) GIMIC / nA T - To further validate these findings, the magnetically induced current densities were calculated using the program GIMIC. The induced current density values followed the same trend as the NICS results: 1e (21 nA T -1 ) > 1d (20 nA T -1 ) > 1a (16 nA T -1 ) > 1b (14 nA T -1 ) > 1c (12 nA T -1 ), supporting our magnetic-based assessment of antiaromaticity. Notably, Valiev et al. also performed GIMIC calculations for compounds equivalent to 1a and 1e and reported a reduction in the paratropic ring current strength of 1a compared to that of 1e. However, our calculations indicate a more pronounced decrease in antiaromaticity owing to the presence of meso-substituents. This difference is attributed to the aforementioned structural discrepancies.