人不可貌相英语怎么说

人不可貌相，海水不可斗量

有人译为：
A man can not be known by his look, nor can the ocean be measured by a dipper.

这样的译法只是直译，如果能够稍加修改，老外就能了解：
A man can not be judged by his appearance, nor can the water in the sea be measured by a bucket.

不过，老外通常的说法是这样的：
We can not judge a person by appearance only. 或 You can not judge a book by its cover.
(意思是：一本书的好坏取决于它的内容，而不是它的封面装帧的漂亮与否。)

参考：http://hi.baidu.com/%D1%D3%D0%C0/blog/item/2fc464cb3f91f31ebe09e683.html

don't judge from the appearance.

Judge not from appearances

A fair face may hide a foul heart.
人不可貌相。

Never judage a person by his appearance.