When does counting 100 Brochos per day start and end?

Question

There's a Halacha/Mitzvah to say at-least 100 Brochos a day.

My question is: what does the term "day" mean in this regard. Does a day start at night, and end the following night (as is the case in most of Judaism), or is there a different time-period used for this count?

Also, assuming it starts at night, does it start at sunset or nightfall (tzeis)?

Answer 1

It turns out that it's actually a machlokes:

• Most poskim hold that it begins at nightfall and continues until the next nightfall
• A few poskim hold that the day starts at morning and continues until the next morning

When necessary, one may rely on the second opinion above. For example, if one didn't say all 100 brachos before nightfall, he should complete the quota before the next morning.

Source: Laws of Daily Living - Volume One

Answer 2

This page here gives you an explanation of how to reach your 100 brachot: The Requirement To Recite 100 Brachos Each Day.

Based on the counting, it appears that your 100 brachot go from maariv to maariv. Otherwise there would be a separate section for Friday vs the rest of chol.(weekdays)

Answer 3

Apparently, its from sunset to sunset.
(See Mogen Avraham Siman 46:8 and Shulchan Aruch HaRav Siman 46)

See here for more sources and details.