I wanted to say that a particular essay written by a student has a poor structure. So, I wrote

"On the low level, your structure can be improved."

But my PhD supervisor told me it should be "At the low level". How do you decide which one is to use?

Edit: We're from the computing department.

  • 4
    Easy. Don't argue with your PhD supervisor.
    – deadrat
    Nov 5, 2015 at 7:37
  • 1
    @deadrat Suddenly I hope my PhD supervisor doesn't have a stackexchange account.
    – Irvan
    Nov 5, 2015 at 7:41
  • Just tell him it was another PhD student in Computer Science at National Univ of Singapore named Irvan. (There really isn't much difference between on an at here.)
    – deadrat
    Nov 5, 2015 at 7:47
  • Personally I would use at, and I can see why your supervisor might have commented to that effect. But plenty of native English-speaking computer scientists in the UK might well have used on.
    – WS2
    Nov 5, 2015 at 7:49
  • @WS2 so I gather that, unlike "on the floor" and "at the floor", here the preposition doesn't really make a difference then?
    – Irvan
    Nov 5, 2015 at 7:51

3 Answers 3


I don't think there's a semantic difference here. Personally, I'd go with "at". For what it's worth, "at" seems to be more popular:

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It is always tricky to choose an appropriate preposition especially among "at", "on", and "in". However, the dictionary shows clear distinction when it comes to a specific usage. For example:

At is used:

as a function word to indicate the rate, degree, or position in a scale or series: 'the temperature at 90' 'at first'


Denoting a particular point or level on a scale: ‘Water boils at one hundred degrees Celsius and at this point changes phase to become a gas, or steam.’

[Oxford Online Dictionary]

Of course, "level" in your example doesn't mean a level on a scale, but it is figuratively similar to it and clearly means "position in series". That's why it is better to use the preposition "at".

Unless "level" means "position in series", "on" can also be used with "level" as follows:

‘The front garden is on a level with this floor’

[Oxford Online Dictionary]

Conclusion: Which preposition to use is largely dependent upon the meaning of an object of a specific prepostion and context. Many usages are idiomatic and it is better to follow usages/examples in a dictionary.


I have also been researching this topic and from observation derived the intuition that one commonly uses "at the level" and "on a level". Checking the various discussions about this topic online (here and in different forums) has only strengthened this impression - when used in a statement with the more definitive article "the", "at" is more common, when used with the less definitive "a", "on" is more common.

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