As of this morning (4/22/2020), I have removed the requirement and/or ability to login or register for the site. You no longer need to login to use the calculators. If you have registered in the past, I will be deleting your accounts over the course of the next several days.
If you still experience problems accessing the calculator please use the contact form to let me know. I think I finally have the bugs worked out, but a larger sample size of feedback would be great.
Sorry for the inconvenience and stay safe,