Objective The purpose of this study was to examine how well two commonly used age‐based prediction equations for maximal heart rate (HRmax) estimate the actual HRmax measured in Black and White adults from the HERITAGE Family Study. Methods A total of 762 sedentary subjects (39% Black, 57% Females) from HERITAGE were included. HRmax was measured during maximal exercise tests using cycle ergometers. Age‐based HRmax was predicted using the Fox (220‐age) and Tanaka (208 – 0.7 × age) formulas. Results The standard error of estimate (SEE) of predicted HRmax was 12.4 and 11.4 bpm for the Fox and Tanaka formulas, respectively, indicating a wide‐spread of measured‐HRmax values are compared to their age‐predicted values. The SEE (shown as Fox/Tanaka) was higher in Blacks (14.4/13.1 bpm) and Males (12.6/11.7 bpm) compared to Whites (11.0/10.2 bpm) and Females (12.3/11.2 bpm) for both formulas. The SEE was higher in subjects above the BMI median (12.8/11.9 bpm) and below the fitness median (13.4/12.4 bpm) when compared to those below the BMI median (12.2/11.0 bpm) and above the fitness median (11.4/10.3) for both formulas. Conclusion Our findings show that based on the SEE, the prevailing age‐based estimated HRmax equations do not precisely predict an individual's measured‐HRmax. Am. J. Hum. Biol., 2013. © 2013 Wiley Periodicals, Inc.