Usually in the camera specifications from the manufacturer they will tell you how many Raw (only) files will fit on a particular size CF card, and how many JPEG files at full resolution and maximum quality. Raw files are compressed by a proprietary method, part of the reason .Raw files require a conversion (utility). With more recent model cameras I think you may find the .Raw file size is not that much larger than the largest, highest quality JPEG.
Any formula for .Raw to actual computer uncompressed file size would be peculiar to each individual camera make and model.

Raw file conversion is very often done most accurately, effectively and efficiently by the software utility supplied by the camera manufacturer - but there are exceptions I'm sure.

As for 3rd party .Raw utilities there are at least a half dozen beside Apple Aperture and Adobe Camera Raw and LightRoom. Which functions best with each different camera model I think today is a guess - when there were fewer camera models and software choices I did a comparison test of most and found that very likely one person might prefer one and another person another depending on what they were looking for in results and the experience of using the software. In other words individual differences in ways of working and how they are using images may be as great a variable as differences between the various software choices in how they function.