Computer on Shabbat

The following is a table of halachic-technological recommendations for using a computer on Shabbat (only for essential security and medical needs).




Notes and Explanations

Turning the computer on

(1) It is best to leave the computer on for all of  Shabbat.

(2) If the computer is off, it should be turned on in a "modified" way (see below).

(3) AN LCD screen such as is used in laptop computers is preferable to a "classic" cathode ray tube.

Incandescent lighting, such as exists in a cathode ray tube, is included in the Torah prohibition of burning a flame. Other computer operations are only forbidden by rabbinical decree.

Operating in a "modified" way

The recommended "modification" is to press the controls using some tool, such as a stick, a spoon handle, or some other object. (Suggestion: use a thimble.)

Using the left hand is not considered a "modification." Replacing the hand with a different limb (such as a foot or an elbow) is usually not very effective. Using an uncommon tool is considered a valid "modification."

Screen saver

A screen saver should be installed that deletes the writing when the screen is not used for a few minutes. (The screen saver definitions should be set to erase the contents of the screen and not to turn the monitor off! This is especially important for a cathode ray tube.)

Temporary writing is prohibited by a rabbinical decree only. It is very doubtful if "writing" on a screen, which does not make use of physical materials such as ink, is in fact included in the Torah prohibition of writing. When a screen saver is used the information is retained in the computer, but a lenient approach is possible in view of the doubts about the definition of writing.


Keyboard entries should be made in a "modified" way (see above). The Zomet Institute has developed a Shabbat keyboard operating on the principle of gramma (indirect operation) which is meant for essential uses.

As noted above, using a thimble is a good way of making a "modification," which can easily be perceived by an observer.


(1) An optical mouse is preferable to a ball mouse.

(2) The (optical) mouse should be moved from one position to another, without using the wheel in the mouse.

(3) A touch-sensitive surface (such as is used in laptop computers) is the worst alternative.

(4) A joystick is comparable to the wheel in a mouse.

(5) If possible, the buttons on the mouse should be pressed in a "modified" way.

(6) The Zomet Institute has developed a Shabbat mouse operating on the principle of gramma (indirect operation) which is suitable for essential uses.

A mouse operating with a ball mechanism and the wheel of an optical mouse are in essence a series of on-off switches. Touch-sensitive surfaces are made up of a large number of tiny on-off switches.

An optical mouse is simply a camera, where the cursor follows the "picture." This is an operation that is permitted on Shabbat.

The usual optical mouse has a red light (a LED) which is turned on only when the mouse is moved. The Shabbat mouse is an optical mouse where the light is kept on all the time. The regular switches on the mouse are replaced by gramma switches through changes in the internal electronics and the programming.

Data storage

The action of storing data has aspects that are more serious than simply pressing the keys of a keyboard or the buttons of a mouse, and this should be done with a "modification." It is best to use a Shabbat mouse for the "save" function.

If a "save" is essential, it might be considered as "building" or "putting on the final touch" (makeh bapatish) from a rabbinical point of view – and such actions are forbidden on Shabbat.


(1) Operating a printer is the most serious action of all computer activity.

(2) Unnecessary printing should be avoided.

(3) The "print" button should only be pressed with a "modification" (see above) or using a Shabbat mouse.

Printing on paper is actual permanent writing and is prohibited on Shabbat by Torah law. It can be done (in a "modified" way) only in a case of a clear medical or security need.

Shabbat Penor computer?

If there are two possibilities available – writing with a Shabbat pen or using a computer – the computer is to be preferred on condition that no printing will be done.

Writing on a computer is not halachically defined as writing but rather involves electronic or electromagnetic records. The writing of a Shabbat pen is real writing, except that from a halachic point of view it is "defective" in that it is temporary.



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