Combining accelerometry with heart rate (HR) monitoring may improve precision of physical activity measurement. Considerable variation exists in the relationships between physical activity intensity (PAI) and HR and accelerometry, which may be reduced by individual calibration. However, individual calibration limits feasibility of these techniques in population studies and less burdensome, yet valid, methods of calibration are required. We aimed to evaluate the precision of different individual calibration procedures against a reference calibration procedure; a ramped treadmill walking-running test with continuous measurement of PAI by indirect calorimetry, in 26 women and 25 men [mean(SD): 35(9)yrs; 1.69(0.10)m; 70(14)kg]. Acceleration (along the longitudinal axis of the trunk) and HR were measured simultaneously. Alternative calibration procedures included treadmill testing without calorimetry, sub-maximal step and walk tests with and without calorimetry, and non-exercise calibration using sleeping HR and gender. Reference accelerometry and HR models explained >95% of the between-individual variance in PAI (p<0.001). This fraction dropped to 73 and 81%, respectively, for accelerometry and HR models calibrated with treadmill test without calorimetry. Step test calibration captured 62-64% (accelerometry) and 68% (HR) of the variance between individuals. Corresponding values were 63-76% and 59-61% for walk test calibration. There was only little benefit of including calorimetry during step and walk calibration for HR models. Non-exercise calibration procedures explained 54% (accelerometry) and 30% (HR) of the between-individual variance. In conclusion, a substantial proportion of the between-individual variance in relationships between PAI, accelerometry and HR is captured with simple calibration procedures, feasible for use in epidemiological studies.