There is no shiur for gmilut hassadim (acts of kindness) as the Mishna says (Peah 1:1)
These are the things that have no measure: [...] acts of kindness, and the study of the Torah. These are
things the fruits of which a man enjoys in this world, while the
principal remains for him in the World to Come: Honoring one's father
and mother, acts of kindness, and bringing peace between a man and his
fellow. But the study of Torah is equal to them all.
Now the fact that there is no limit doesn't mean chesed is always first priority. See for instance here
If a man is occupied with learning of Torah, his Torah takes
precedence. When one is engaged in one mitzva, he is generally
exempted from another mitzva. If while learning Torah the opportunity
for chesed presents itself, if someone else is able to perform the
chesed, the man should not interrupt his study. If, however, no one
else is available or willing to perform the chesed, the law (Yora Daya
246:18) says to do the chesed. Since the person or cause means that
there is need, you are required in order that the need be fulfilled.
Then, when the chesed has been accomplished, return to your learning.
If more people request chesed (practical kindness) or tzadaka
(charity) than you can provide, there is an elaborate and complex
order of priorities which have to be studied or discussed with a Torah
scholar. Generally, higher priorities go with the closer relative, the
one who dwells in a location more close to you, the greater person in
Torah, a Kohain over a Levi over a Yisroel over a momzer, a female
over a male, a destitute person over a wealthy person, the greater the
measure or suffering or weakness. Since actual cases can be complex
(e.g. a talmid chochom momzer is over an ignorant Kohain), a rav must
be asked who has the higher the priority.