Ok, there's no reason to mess around here. Your dining table should be 30 inches tall. That's 76 centimeters.
You can deviate from this standard a very little bit - like 29 inches to 30.5 inches. Less than 29 is too short, and more than 30.5 is too tall.
Learn from my mistakes
I made a table recently that had extension hardware and the legs had to mount to that. The table top was then attached to the moving slides. I made the top from 2" thick walnut, and the 28" legs ended up about 1.25" below that. The table ended up being 31.25" tall! From a distance, it looked fantastic! Then I sat in a chair and pulled in for an imaginary meal. Oh no! I felt like a little kid sitting at this monster table.
I had to rework how the legs would attach (they were metal, so I could not just shorten them). I got the legs to be just under the top and re-tested my fictional meal. Perfection!
A table that is too short feels immediately wrong, too. Besides the possibility of hitting thighs on a table skirt, your guests will feel like they are at a child's tea party.
Conclusion
Plan for 30 inches. Stay within half an inch of that and you are golden! Not sure how long the table should be? Take a look at this.
