Cooking, as we know, is permissible on Yom Tov. The question arises as to whether a person who cooks rice, for example, on Yom Tov (such as Sephardim on Pesach, who allow eating rice that has been checked three times), may measure the rice in order to determine how much to put in the pot. Is measuring permitted on Yom Tov for the purpose of cooking?

Chacham Ovadia Yosef writes in Halichot Olam (listen to audio for precise citation) that one may measure rice on Yom Tov only if he is not meticulous and exacting in his measuring, meaning, that he is not interested in determining the precise amount, and wishes to determine merely the rough estimation. All the more so, Chacham Ovadia adds, it is permissible to measure in an ordinary cup, to get a rough estimate of the amount, rather than in a measuring cup.

Is it permissible to smoke a cigarette on Yom Tov?

Chacham Ovadia Yosef addresses this question in the subsequent passage in Halichot Olam, noting that physicians have determined that smoking poses danger to one's health, and one should therefore avoid smoking. The question he addresses concerns someone who had grown accustomed to smoking and has been unable to stop this habit.

Chacham Ovadia rules (listed to audio for precise citation) that a regular smoker who would experience discomfort by refraining from smoking on Yom Tov may smoke on Yom Tov. However, one who does not smoke regularly, and wishes to smoke for enjoyment, rather than to alleviate discomfort, may not smoke on Yom Tov. It should be noted that even when smoking is permissible on Yom Tov, one must light the cigarette from an existing flame, as kindling a flame is forbidden on Yom Tov. Furthermore, he may not extinguish the fire after smoking; he must let the cigarette go out by itself.

Summary: One who cooks on Yom Tov may measure the ingredients only if he is interested in a rough estimate, and not the precise amount. A smoker, who would experience discomfort on Yom Tov if he would refrain from smoking, may smoke on Yom Tov, provided that he light the cigarette from an existing flame and that he does not extinguish the flame after he finishes smoking. One who would not experience discomfort by refraining from smoking may not smoke on Yom Tov.