Opening a can of beer on Shabbos

I was at a Shabbat Sheva Brachot in Antwerp, and I bought this really good Belgian beer le'kavod Shabbat. But am I allowed to open it on Shabbat?

Thank you for your question.

The Answer:

You should open it before Shabbos.

The Answer explained:

Opening a can of beer has been a significant topic of discussion among the poskim , as it may involve melachos of Shabbos.

First, I will explain the different Melachot that we need to consider when opening a can on Shabbat, and then I will write the psak halacha .

Asiyat Petach – Creating an opening.

On Shabbat, it is forbidden to create an opening in an item. This is a biblical prohibition because, before the opening was made, the utensil was not usable. By creating an opening, it becomes a kli (a functional vessel), allowing one to store food inside and take food out through the opening. This is considered a melacha called Boneh (building) or Makeh BePatish (completing a vessel).

As we explained, by making an opening in a utensil, you have now created a useful item. The question is: what is the halacha if you are only making the opening to remove the food stored inside the can and then intend to discard it? Perhaps, since your intent was solely to access the food or drink inside and not to create a usable can for further use, this would not be considered a melacha prohibited on Shabbos. It could be viewed as merely removing a wrapper from food, which is permitted.

The Chazon Ish prohibits this in Siman 51, Se’if Katan 11, for several reasons. Here are two of them:

1. There is a concern that one may not empty all the contents immediately after opening the can, and therefore, it will become a kli that has practical use.
2. Even if one’s intent is to empty the contents and discard the can immediately after opening, this does not change the status of what has been done. The can is still considered a usable kli , and one’s intent to throw it away does not negate this fact.

Mechatech – Cutting to a specific size

Another melacha to consider when opening a can on Shabbos is Mechatech —cutting something to a specific size or shape. This prohibition applies when one intentionally cuts an item to a precise measurement or form that is useful.

This is a quote from the Rambam:

רמב"ם הלכות שבת פרק יא הלכה ז

המחתך מן העור כדי לעשות קמיע חייב, והוא שיתכוין למדת ארכו ומדת רחבו ויחתוך בכונה שהיא מלאכה, אבל אם חתך דרך הפסד או בלא כונה למדתו אלא כמתעסק או כמשחק הרי זה פטור,

Rambam, Hilchos Shabbos, Chapter 11, Halacha 7:

One who cuts a piece of leather in order to make an amulet is Chayav, provided that he intends for its length and width and cuts it deliberately, as this constitutes a melacha. However, if he cuts it in a destructive manner, or without intent for its specific measurement but rather as an incidental act or in a playful manner, he is exempt.

So one could argue that the same applies when opening a can of drink—it involves a deliberate cut, which may be considered Mechatech . Since the lid is removed in a precise manner, creating a specific opening, this could fall under the prohibition of cutting an item to a designated size or shape on Shabbos.

Therefore, there are poskim who are stringent and prohibit opening a can on Shabbos due to the issur of Mechatech .

So Le'halcha we say that due to the melachot that is involved in opening a can on Shabbos Hagaon Harav Amrom Fried Shelitah says that you should open the can before Shabbos.

Wishing you all the best.

Chazon Ish, Siman 51, Se’if Katan 11

Rambam, Hilchos Shabbos, Chapter 11, Halacha 7