A fast, no-signup pace calculator for runners — from first-timers planning a 5K to marathoners dialing in race-day splits.
Four tools on one page: pace/time/distance conversion, race-time prediction using the Riegel formula, training pace zones derived from your 5K speed, and split tables for any race distance.
Pace is total time divided by distance. Race-time prediction uses Riegel's formula: T₂ = T₁ × (D₂ / D₁)1.06 — the exponent reflects how runners slow down as distance grows. Training zones follow the offsets used in Daniels' Running Formula and similar plans.
The calculations are mathematically exact for the inputs you give. Real-world race times also depend on training history, fueling, terrain, weather, and pacing — adjust predictions based on context. The training paces are guidelines, not prescriptions.
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Not medical advice. Always consult a coach or physician before starting a training program, especially if you have an existing health condition.