When I buy clothes online, I end up throwing more than half of them away because I didn't try them on to make sure they fit.
この場合、次のような言い方ができますよ。
ーWhen I buy clothes online, I end up throwing more than half of them away because I didn't try them on to make sure they fit.
「通販で服を買うと、ちゃんと合うか試着できないから半分以上を処分する羽目になる」
to buy clothes online「通販で洋服を買う」
to end up throwing away「捨てる羽目になる」
to make sure「確かめる」
ご参考まで！
When I purchase clothes online, I end up having to throw away more than half of them.
This is because despite the size chart, I cannot try on the items and most of the clothes are too big and the shoes too small.
ご質問ありがとうございます。
"When I purchase clothes online,"＝「ネットで服を買うと、」
"I end up having to throw away more than half of them."＝「半分以上は捨てる羽目になります。」
"This is because despite the size chart,"＝「これはサイズ票があっても」
"I cannot try on the items and most of the clothes are too big and the shoes too small."＝「商品を試着できず、ほとんどの服は大き過ぎて、靴は小さ過ぎることになります。」
ご参考までに。
When I shop for clothes online, I often find myself throwing away over half of them because I can't try them on first.
こんにちは！
ご質問ありがとうございます。
先のアンカーさんが丁寧に回答されていますので、ここでは他の例を挙げてみます。
When I shop for clothes online, I often find myself throwing away over half of them because I can't try them on first. Typically, the clothes turn out to be too big, and the shoes end up being too small.
とすると、『オンラインで洋服を買うと、試着できないので気づいたら半部以上の服を捨てている。大体の場合、服は大きすぎて靴は小さすぎる。』と言えます。
参考になれば幸いです。
カナダ 
アメリカ合衆国 
日本 
