Race Pace Calculator

The calculator operates in two modes. In pace calculation mode, you enter a target finish time and the tool distributes the required pace across each phase — factoring in any phases you've manually locked so the remaining phases absorb the adjustment. In target calculation mode, you enter a pace for every phase and the calculator projects the total finish time. Both modes support adding or removing phases and assigning any distance split you choose.

Why the negative split works. Starting the first 30% of a race 5–10 seconds per kilometre slower than target pace, holding even effort through the middle 50%, then finishing the final 20% faster is one of the most consistently supported pacing strategies in endurance research. The physiological reason: starting too fast depletes glycogen and accumulates lactate earlier than necessary, causing involuntary slowdown in the final third. A conservative start keeps lactate low and preserves glycogen stores, so the final kilometres feel controlled rather than a damage-control exercise.

For a plan built from your actual fitness level — where paces are derived from VDOT rather than manually set — the Race Strategy Calculator maps conservative, optimal, and aggressive regimes to each phase automatically.