Peter Riegel

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Peter S. Riegel
  • BS Mech Eng, Purdue, 1959
  • MME, Villanova, 1966
Occupation Research engineer
Known for Race time prediction formula

Peter Riegel is an American research engineer who developed a mathematical formula for predicting race times for runners and other athletes given a certain performance at another distance. The formula has been widely adopted on account of its simplicity and predictive accuracy.


Riegel gained a BS in mechanical engineering from Purdue University in 1959 and his masters from Villanova University in 1966.[1]

He was a research engineer at Battelle Memorial Institute in Columbus, Ohio, researching the development of deep-sea diving equipment as well as air flow in coal mines. He has numerous published articles on waste-water treatment, underwater life support, motorcycle mechanics and distance running.[1]

Riegel founded and edited Measurement News, the newsletter of the Road Running Technical Council of USA Track & Field. He is also a founding member of the Association of Road Racing Statisticians.

He holds a patent for an automatic trip fill nozzle[2] and another for an exhaust regulator valve for push-pull diving system.[3]

Race time prediction[edit]

In a 1977 article for Runner's World Magazine, Riegel proposed a simple formula for comparing relative performances at different distances.[4] The formula is most commonly quoted as:


  • T1 is the time achieved for D1.
  • T2 is the time predicted for D2.
  • D1 is the distance over which the initial time is achieved.
  • D2 is the distance for which the time is to be predicted.

Riegel expanded on his thesis in an 1981 article for American Scientist, stating that the formula t=axb concerns activities in the "endurance range", namely lasting between 3.5 and 230 minutes. The analysis deals with running, swimming and walking.[1]

The simplicity of the formula and its predictive accuracy has resulted in it being adopted widely by websites such as Runner's World.[5] Some sites have modified it, stating that the value of 1.06 given for the exponent b in the formula results in seemingly unachievable predictions for longer distances.[6]


  • Riegel, Peter (1971). Summary Report on Development and Construction of an Improved Line Stopper: To American Gas Association, Inc. Battelle Memorial Institute, Columbus Laboratories. 
  • Riegel, Peter (1972). Improvements to the Control Block of the Mark VI Mod 2 SCUBA. Defense Technical Information Center. 
  • Riegel, Peter (1977). Divers Heating Hose Comparison Study. Defense Technical Information Center. 
  • Riegel, Peter (1981). Investigation of Methods of Inspired Gas Heating. Defense Technical Information Center. 
  • Riegel, Peter (1982). Development of a Hydrogen-Fueled Diver Heater. Defense Technical Information Center. 


  1. ^ a b c Riegel, Peter S. (May–June 1981). "Athletic Records and Human Endurance". American Scientist. 69: 285–290. 
  2. ^ US patent 3710831 
  3. ^ US patent 4037594 
  4. ^ Riegel, P. S. (August 1977). "Time Predicting". Runner's World Magazine. 
  5. ^ Carter, Kate (6 February 2013). "The best running websites". The Guardian. Retrieved 3 January 2014. 
  6. ^ "Improved Riegel Calculator for Half Marathon to Marathon". Fetch Everyone. Retrieved 3 January 2014.