There are several posts over the past few days regarding this. Yes, it's down. You can use Soapmaking Friend, Soapee or WSP has a calculator very similar to Soap Calc
I too was wondering if it was just my system or was it down. Instead of clicking the contact link on Soapcalc’s website, I saw that it was down from another website called “downforeveryoneorjustme”
Decided to use one of the alternates until it’s back up. Thankfully it’s working again.