HALF-MARATHON PACING
Sub-two-hour half marathon: exact pace and useful checkpoints
A half marathon includes a partial final kilometer. Keep the full distance in the calculation, especially when your target sits close to a time boundary.
Use the full half-marathon distance
Using 21.0975 km, exactly two hours corresponds to 7,200 ÷ 21.0975 = approximately 341.27 seconds per kilometer: 5:41.27. An average of 5:42 per kilometer is above that boundary. A displayed rounded pace by itself is not a guarantee of a sub-two-hour finish.
For a concrete illustration, the checkpoints below use 1:59:30. This is a mathematical example with a 30-second difference from two hours, not a recommended buffer or a judgment about your current ability.
Inspect a 1:59:30 split sheet
| Distance | Cumulative time |
|---|---|
| 5 km | 28:19 |
| 10 km | 56:39 |
| 15 km | 1:24:58 |
| 20 km | 1:53:17 |
| 21.0975 km | 1:59:30 |
The average for this example is approximately 5:39.85 per kilometer. The final 1.0975 km after the 20 km marker is part of the target, not an optional extra. Calculate the cumulative times from the unrounded average so small rounding errors do not accumulate at every kilometer.
Make units and timing explicit
If you use mile markers, build a mile-based sheet rather than relabeling kilometer rows. If you use a watch distance alert, keep its recorded distance distinct from the event markers. Both are useful references, but they do not necessarily announce each checkpoint at the same physical location.
A printed plan should identify whether a time is cumulative or for the latest split. Check that its final row equals the chosen finish time and that the sheet includes the partial final unit. The Runome splits tool can generate and print those rows.
Keep preparation separate from the pace equation
A pace sheet answers how the target divides across distance. It does not assess long-run preparation, conditions or how the effort may unfold. Review recent relevant activities and the wider history before deciding how to use an estimate.
Runome's activity analysis and race-readiness views address different questions from a simple split calculator. Read race-prediction sensitivity when extrapolating from a shorter event. Use the actual recorded splits afterward to describe what happened, including any stops or route conditions that changed the interpretation.