Are both prepositions correct? Do they mean the exact same thing? I have had this doubt myself and I decided to do some research and clear it out for once and all.

When I have such doubts on English language usage, I go to – surprise, surprise – Ludwig and I searched it for both expressions.

Rules and usage

According to Ludwig, on the level is 100% correct. ‘On the level is’ an idiom that is used to say that someone is honest and trustworthy. A clear example of this usage that I found on Ludwig is: “I've tried to be on the level with you”. Beyond being an idiom ‘on the level’ is also used literally, meaning that two things are on the same level and are hence comparable.

Afterwards, I searched Ludwig for ‘at the level’ and I discovered that it is as frequent as ‘on the level’. Moreover, both ‘at the level’ and ‘on the level’ occur in similar and apparently interchangeable contexts. The only difference between the two is that ‘at the level’ is not used to describe the moral virtue of honesty of someone.

Once I knew that ‘on the level’ and ‘at the level’ were often interchangeable, I wanted to know if are there other contexts in which they are not interchangeable. I started googling and ended up reading a discussion about this on English StackExchange. Unfortunately, none of the users had arrived at a satisfactory answer in my opinion.

Ludwig’s wrap up

The final word on this is that the English language depends on content much more than it does on rules. But the cases in which ‘on the level’ is used as an idiom, both ‘on the level’ and ‘at the level’ seem to be on the same level.

"on the level" "at the level" idiom "same level" interchangeable


P.S.

While I was trying to solve such a multifaceted existential question I was listening to Leonard Cohen’s song titled “On the level”

and an album titled 'On the level' by the Status Quo, a UK rock band that used to be quite popular in the seventies. Have fun.