Due to the recent updates, Hitpoints(Constitution) and Prayer no longer have an effect on your combat level.
The calculator can also act as a Hitpoints Calculator. Simply enter the levels of other skills and then hit [Hitpoints] button and the calculator will try to predict your hitpoints level based on other skill levels.
Combat Calculator accuracy is nearly 100%. This calculator uses the actual combat level formula provided by Jagex: http://services.runescape.com/m=rswiki/en/Combat_Formula
Due to the new Evolution of Combat(EOC) update, maximum combat level is now 200. This calculator has been updated with a new combat formula to support these new changes.
*** NEW *** - with Old School Runescape back, this calculator now supports calculating combat for both versions.