GNU `find` seems not work with -size to find the file whose size is less than *M

Question

I want to find the file whose size is less than 1M, so I write as find . -size -1M. But it seems not work indeed:

find . -size -1M | xargs ls -lh
-rw-rw-r-- 1 xyz xyz 0 Apr  2 14:48 ./test/score
-rw-rw-r-- 1 xyz xyz 0 Apr  2 14:48 ./test/ir1

On the contrary, it's amazing that find . -size 1M works.

Answer 1

From man find:

The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes.