I follow the opinion that rotary shavers are okay to use because the way they shave is actually more similar to that of a scissor than of a razor. However, by that same opinion, or by the authorities that proclaim that same opinion, can I also use the back trimmer that pops out as seen in this picture?

Electric Rotary Shaver

  • I asked this to a local rav once and he said yes.
    – andrewmh20
    Commented Dec 31, 2014 at 15:28
  • @andrewmh20 Would you happen to know the reason with that psak?
    – rosenjcb
    Commented Dec 31, 2014 at 15:29
  • Nope. Though looking at it logically, it seems that from the way the trimmer appears to work it is even MORE like scissors than the shaver itself, no?
    – andrewmh20
    Commented Dec 31, 2014 at 15:32
  • As in, there are 2 components that move back and forth across each other.
    – andrewmh20
    Commented Dec 31, 2014 at 15:34

2 Answers 2


Excerpt from a Star K article about shavers:

Hagaon R' Moshe Feinstein זצ"ל was of the opinion that the גמרא 's statement - איזהו גילוח שיש בו השחתה הוי אומר זה is teaching us that only the תער , the straight-edged razor, is the Torah's forbidden form of השחתה and גילוח . Any other method of השחתה and גילוח would be permitted. Based on this fundamental understanding of the גמרא , electric shavers would be permitted even if the shaver removed facial hair beneath the skin, since the shaver works in a scissor-like and not razor-like action.

However, due to the increased sharpness of the blades of the rotating heads it is conceivable that the blades could cut the beard hairs off before the combined cutting of blade and screen. Therefore, even according to the Poskim that permit electric shavers, this shaver would be problematic, because it would be cutting like a תער , which is אסור . Can one practically determine whether the shaver in question is a kosher model?

Hagaon R' Moshe Feinstein זצ"ל , who permitted the use of electric shavers used a criteria similar to the shochet who would demonstrate how sharp his חלף (shechita knife) was. To show the sharp edge of his knife, a shochet would take a hair from his beard, and holding the hair in one hand the shochet would see whether the חלף cut the dangling hair. If the hair was severed, the shochet's steel passed the test.

So too, in a similar manner, R' Moshe would often test the sharpness of an electric shaver's blades. He would take a beard hair and test the blades! The shaver would be acceptable if the hair was held taut and was not split in half.

It appears that the pop-up trimmer is no sharper than the rotary blades. IMO, they are duller than the blades, actually. So, it seems that it should be OK.

If @Shokhet is reading this, I wonder if he has performed Rav Feinstein's test using his Shochet knife?


Yes, absolutely. It doesn't cut beneath the skin, and none of its individual components are sharp enough to cut a whisker.

  • 1
    I like your answer, but it'd might be helpful, just for the sight itself, you include citations explaining why cutting beneath the skin and being dull are components of halachic shaving.
    – rosenjcb
    Commented Dec 31, 2014 at 15:39
  • Do any razors cut beneath the skin??
    – Double AA
    Commented Jan 21, 2021 at 18:17

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .