If you have a standard sofa, then it would be about 25 inches. Then, you just need to find the right table with the right height. Most end tables in the market are around 22 to 30 inches. However, if you are still confused in finding perfect end table, there is another rule. Always find end table with height lower than your sofa armrests.
That is the rule; the simple one of choosing end table for living room. By having known the basic rule, now you may easily find perfect end table. The next step is finding ideal table design for your room. Moreover, it is up to your taste.