How to use the half marathon pace chart
Find your goal time on the left. Read across for the pace per km and per mile, and the clock time at each 5K.
The 10K split is the one to watch. More than 30 seconds up on it, and you have probably gone off too fast.
Rows go up in 5 minute steps. For a time in between, the calculator above works out any finish exactly.
Even or negative splits
The half marathon is long enough for a fast start to hurt. It is short enough to race hard over the last 5K.
Most runners do best at even pace, or with the first half a little slower.
For a 2 hour half, a 1% negative split reaches halfway in about 1:00:36 rather than 1:00:00. The second half then takes 59:24.
In practice: settle into goal pace by 3K and hold it to 15K without pushing. Then use whatever you have left.
Hills, wind and GPS
The chart assumes a flat course on a calm day. On hills, run the climbs by effort and win the time back downhill.
Chasing chart pace uphill costs more than it gains.
GPS also reads a little long over 21.1 km. Check your splits against the course markers, or run a second or two per km quicker than chart pace.
Find your goal pace with the plan builder
A recent 10K or 5K is the best guide to a realistic goal. Look it up in the VDOT chart or the race time predictor for the half marathon it is worth.
Then build a plan from that race time. Your easy, threshold and interval paces come from today's fitness, not from the goal.
The VDOT column is the fitness score each finish time represents in Jack Daniels' model. Equal VDOTs at different distances are the same fitness, laid out in the VDOT chart.