Predict your 5K, 10K, half marathon and marathon finish time from a recent race result using Riegel's formula. Get personalised training paces.
Predicting your marathon finish time from a shorter race result is one of the most reliable training tools available to runners. This calculator uses Riegel's formula, developed by Dr. Peter Riegel and published in American Scientist in 1981: T2 = T1 x (D2/D1)^1.06. The exponent 1.06 accounts for the increasing fatigue factor over longer distances. So if you ran a 10K in 50 minutes, your predicted marathon time would be approximately 4 hours 27 minutes - a useful benchmark when building a training plan.
Distance running has seen explosive growth in India over the last decade. The Tata Mumbai Marathon, first held in 2004, now attracts over 55,000 runners annually and is an IAAF Gold Label event. Major city marathons in Delhi, Bengaluru, Chennai, Hyderabad, and Kolkata collectively draw hundreds of thousands of participants each year. Indian runners are improving rapidly - Niharika Paul set a women's marathon national record of 2:37:41 in 2023. Community running clubs have sprung up in Tier-1 and Tier-2 cities, creating demand for tools that help amateur runners set realistic race goals.
Beyond finish time prediction, this tool generates personalised training paces - easy run, tempo, and interval paces - helping runners structure their weekly training loads based on their current fitness level and target race distance.