~わりに
Surprisingly, considering the circumstances
You’ll be able to describe a result that differs from what you would expect based on a stated condition.

値段が安かったわりに、とてもおいしい桃でした。
nedan ga yasukatta wari ni, totemo oishii momo deshita.
What do you think this sentence means?
Considering how cheap the price was, they were very delicious peaches.
Compared with what you would expect
~わりに means “considering...” or “for....” The first part gives a fact that suggests one expectation; the rest gives a result that is different from that expectation.
よく食べるわりに、やせています。
yoku taberu wari ni, yasete imasu.
They are thin, considering how much they eat.
この店は有名なわりに、おいしくないです。
kono mise wa yuumei na wari ni, oishikunai desu.
For such a famous restaurant, the food is not good.
Attach it to the stated condition
Use noun + のわりに, な-adjective + なわりに, い-adjective + わりに, or plain verb + わりに. The contrast can be favorable or unfavorable.
彼は年齢のわりに若く見えます。
kare wa nenrei no wari ni wakaku miemasu.
He looks young for his age.
~わりに vs ~にしては
Both mean “for …” and introduce a result that goes against expectations. ~わりに weighs the result against a scale such as age, price or amount (年齢のわりに, 安いわりに), and can follow adjectives. ~にしては takes one specific fact or category as the standard (六十歳にしては) and follows a noun or verb, not an い-adjective.
~わりに, considering
父は年齢のわりに、若く見えます。
chichi wa nenrei no wari ni, wakaku miemasu.
My father looks young for his age.
Compares his looks with his age in general.
~にしては, for (a specific case)
父は六十歳にしては、若く見えます。
chichi wa rokujussai ni shite wa, wakaku miemasu.
My father looks young for a sixty-year-old.
Takes the specific fact of being sixty as the standard.
この店は、値段が高いわりに量が少ない。
kono mise wa, nedan ga takai wari ni ryou ga sukunai.
This restaurant’s portions are small considering how expensive it is.
祖母は年のわりに、スマホの使い方をよく知っている。
sobo wa toshi no wari ni, sumaho no tsukaikata o yoku shitte iru.
For her age, my grandmother knows a lot about using a smartphone.
この洗濯機は、音が静かなわりに、パワーが強い。
kono sentakuki wa, oto ga shizuka na wari ni, pawaa ga tsuyoi.
This washing machine is powerful, considering how quiet it is.
7 more examples in the grammar path — free for a limited time.