Actually, I'm really surprised at the deep seated confusion on this issue. It's true that you can calculate a CoC on the negative or sensor knowing just the focal length of the lens, the f stop and the distance to subject. But without knowledge of both the format of the negative and the size of print that will result from a specific degree of enlargement from that negative or sensor, the CoC has an unknown effect on DoF. It is therefore not a DoF calculation, but a CoC calculation and incomplete as regards DoF considerations.

To calculate the true DoF that will be apparent on a given size print it is necessary to know 5 essential ingredients.

1. The format of the film or sensor, and included in that is the amended format resulting from post shooting cropping.

2. The degree of enlargement from the film format or amended format (2x, 4x 8x etc).

3. The focal length of the lens.

4. The f stop.

5. The distance to subject.

If any one of these five ingredients is missing, then accurate DoF calculation is not possible (with regard to a complete composition, of course).

It's possible to use a couple of the variables as a constant to create a formula that only applies to a specific format and degree of enlargement, thus giving the impression that format has no bearing on the matter. But this is pure illusion.

If y = 2x so that I can substitute 2x for all instances of y in the equation, should I then pretend that y doesn't exist? That would be foolish. If y doubles in size then so does 2x.