My statement “Like the SFPF calculator it apparently uses material K-Factors for its calculations. A recent earlier update added K-Factors for wood, but they’re 2-3 times higher that they should be IMO. But it so happens that the one just added for acrylic (and most other plastics), should be “close enough” for most woods [especially since they’re likely crude approximations anyway]” was apparently too generous for softwood (it’s much farther off) (https://community.carbide3d.com/t/speeds-feeds-power-and-force-sfpf-calculator/16237/52.)
You might want to consider monitoring spindle power as discussed here.