生日快乐用英语最简单的是Happy Birthday。意义更丰富的表达如下：

1、It is not everyday you have a birthday, so hope you have a wonderful one. May it be followed by days and weeks and months and years of happiness for you!

不是每天都能过生日，希望你今天生日快乐，愿你年年岁岁幸福永伴!

2、The kindest friend there could ever be is the kind of friend you are to me.Happy Birthday!

世上如有诤友， 那就是像你对我那样关怀的朋友。祝你生日快乐!

3、My birthday wishes to you are the warmest. May all the plans you are making work out just right for you and may life always bring the best things your way.

热烈祝贺你的生辰!愿你的计划都能实现、愿你的生活永远美丽!

4、Wishing you a wonderful birthday.You make this world a nicer place just by being so kindhearted.May this day that is all your own hold happiness for you and the years to come be filled with all the best things,too.

祝你生日快乐，你的善良使这个世界变得更加美好，愿这完全属于你的一天带给你快乐，愿未来的日子锦上添花!