vDOTÂ calculator based on values are derived from Daniels’ Running Formula, 2nd edition
I like this calculator since you can enter the distance and time for any maximal value run that you have, and know what your vDOT value is…the closer the distance is to your target race distance, the better it will be in estimating your race performance.
For the Ironman marathon, use the Easy/Long pace to get an idea of what your potential is on the run based on your current vDOT from 5K upward…again, ‘presuming’ that you’ve done ‘suitable’ race specific training
http://www.attackpoint.org/trainingpaces.jsp?eqdist=1500&vdot=42