Butyr Fentanyl Potency?

[Skyradkey]

I realize that there are approximations out there but the approximation is within a wide range for B-F. I have seen both 1/30 potency of fentanyl all the way up to 1/4 potency of fentanyl. Seems that it is closer to the 1/4 potency but not quite that strong. Thinking more in the 1/5-1/10 potency of fentanyl range. Anyone with more experience have a good estimation assuming >98% purity?