Iain-- It's also on the internet. Just type the key words into your browser: --conversion Fahrenheit Centigrade-- and a number of conversion tables come up. I keep one handy at the computer because I think in Fahrenheit terms having grown up with it, and the gradations are finer without having to use decimal fractions of degrees. We just had -15° F a week or so ago (~26-27° C) , and I'm wondering if my Zantedeschia albomaculata has survived. It went through days of 0° F for the last 2 years, and bloomed, no particular protection, planted about 4" deep. Am trying some other S. Africans for hardiness.