7 min/mi: run 6 min/walk 30 sec 7:30/mi: run 5 min/walk 30 sec 8 min/mi: run 4 min/walk 30 seconds 9 min/mi: run 4 min/walk 1 min 10 min/mi: run 3 min/walk 1 min 11 min/mi: run 2:30/walk 1 min 12 min/mi: run 2 min/walk 1 min 13 min/mi: run 1 min/walk 1 min
In the half marathon I recommend using a 1-1 (run one minute, walk one minute) for the first half mile, then either 1-1 or 2-1 for the second half mile. At that point, the runner can transition into the run-walk-run strategy listed above.
In the marathon, I recommend using a 1-1 for the first 1-3 miles, then gradually transition to the strategy that works best for the goal pace, on that day.
There is a trend among half and full ironman athletes to run faster at the end with more liberal walk break portions than the pace would indicate above. For example, many 9 minute Ironmen use a 3-1 and some have used 2-1 for the half and then shifted to 3-1 or 4-1.