そんなもの

also: そんなもん · そういうもの · そういうもん

Meanings

that's the way it is; such is life; that's how things are

Used to express resignation, acceptance, or a matter-of-fact explanation that something is simply the nature of things. Often carries a nuance of 'it can't be helped' or 'that's just how it goes'.

人じん生せいはそんなものだ。
That's just how life is.
失しっ敗ぱいは成せい功こうのもとって言いうけど、まあそんなものかな。
They say failure is the mother of success, but well, I guess that's how it goes.

Related words

そういうこと
そういうこと is more often used to confirm understanding ('so that's what you mean'), while そんなもの expresses resignation or acceptance of a situation.
しょうがない
しょうがない explicitly means 'it can't be helped', while そんなもの is more about accepting the nature of things without necessarily implying helplessness.

Written forms

そんなもん
Casual contraction of そんなもの, common in informal speech.
そういうもの
Slightly more formal or explanatory variant; literally 'that kind of thing'.
そういうもん
Casual contraction of そういうもの.

Etymology

Combination of the pre-noun adjectival そんな ('such') or そういう ('that kind of') with the noun もの ('thing'). The phrase grammaticalized into a set expression meaning 'that's the way it is'.