Marathon & Distance Running

Calculate adult BMI from metric or imperial height and weight. See CDC screening categories, formula steps, and limitations without treating BMI as a diagnosis.

Calculate average pace per kilometer and mile plus speed from one entered distance and elapsed time. Transparent constant-pace arithmetic, not a race predictor.

Calculate a user-entered heart-rate-reserve percentage range with the Tanaka age-estimated maximum. Shows formula and limits; never prescribes training zones.

Reproduce mean kilometre/mile pace and speed from one completed source-owned race result and retained event distance, with an optional same-result displayed-pace comparison—without creating targets, splits, predictions or training advice.

Compare adult BMR equations and a selected activity-multiplier TDEE scenario without generating calorie, macro, or meal prescriptions.

Convert a user-selected energy total and carbohydrate, protein, and fat percentages into calories and grams with adult AMDR context.

Calculate your running pace per mile or kilometer from race time and distance. Free running pace calculator for marathon training, race planning.

Predict finish time at a new distance based on a recent race result. Free running race predictor calculator for marathon training, race planning.

Calculate Karvonen heart rate training zones for running. Free running heart rate zones calculator for marathon training, race planning, and pace analysis.

Estimate weekly training load (arbitrary units) from volume and intensity. Free running training load calculator for marathon training, race planning.

Predict marathon finish from a recent half marathon result. Free marathon finish time calculator for marathon training, race planning, and pace analysis.

Compare adult beverage water with National Academies total-water Adequate Intake references while keeping food water and individual needs explicit.

Estimate adult basal metabolic rate with Mifflin–St Jeor, revised Harris–Benedict, or Katch–McArdle, plus a clearly labeled activity-multiplier TDEE scenario.

Estimate adult body-fat percentage with a sex-specific U.S. Navy circumference equation, explicit measurement guidance, unit conversion, and non-diagnostic limitations.