This paper presents a comparative study on the influence of some typical soil characteristics on the cone and ball factors (N _kt and N _ball). Experimental data from CPTU and ball penetration test (BPT) on Busan (two sites), Ariake, and Mihara clays were taken into analysis. In contrary to the conclusions from existing FE analysis and experimental results at limited sites that N _ball is independent on rigidity index (I _r) and normalized stress difference (Δ), N _ball was found to clearly increase with the increase in I _r and to increase or decrease with Δ. This disagreement is attributed to different inherent characteristics of natural clays. Both N _kt and N _ball decrease pronouncedly with the increase in normalized shear strength ( s uFV / s ′ v 0 ) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429505980/63e565bd-23e1-4d0b-a1f1-5a46a30492fe/content/eq401.tif"/> , however the factors expose to have no definite correlations with sensitivity (S _tFV) and plasticity index (I _p) at the investigated sites.