Calculator
Fahrenheit and Celsius
The USDA states its bands in Fahrenheit and the FAO bulletin states its optima in Celsius. Same ferment, two scales.
Result
22.2degrees C
Working
C = (F - 32) x 5 / 9 = (72 - 32) x 5 / 9 = 22.2 C
Result
69.8degrees F
Working
F = C x 9 / 5 + 32 = 21 x 9 / 5 + 32 = 69.8 F
Why this needs a calculator at all
This site prints both as its sources printed them and converts neither in place. The USDA recommends 70 to 75 F for kraut and dill pickles, warns that below 60 F kraut may not ferment at all, and that above 75 F it goes soft. The FAO bulletin puts the sauerkraut optimum at 21 C and says most lactic acid bacteria work best between 18 and 22 C. Those are the same window described twice.
What this is not
Arithmetic, not advice. It converts the number you type; it does not know what you are fermenting, how warm your kitchen is or whether your salt is pure. Nothing on this page certifies that a preparation is safe, and no result here should be read as a recommendation to ferment at any particular strength. The published parameters, with the sentence each came from, are on the tradition pages, and what can go wrong is on safety.