OK without finding a calculator, since January of this year when I aquired my first SWK, I have another last week and one in the post. I also have one more on order. Based on 4 months average of 30 days/month that is one a month so I'm 12 kilts per year. That is what? 1.2765957446808510638297872340426 kiloHamish? Expect that to drop faster that a kilt lifter's moral standing soon though.