Background <p>A finger pulse monitor (FPM) offers multiple advantages for monitoring heart rate during exercise in comparison to chest worn monitors, including: enhanced testing efficiency; less invasive, particularly for vulnerable populations (e.g. children); and, reduced cost. The purpose of this study was to establish the test-retest reliability of an FPM device for monitoring heart rate during a 3-minute step test (3MST₃₀) to estimate cardiorespiratory fitness in a lab and school setting, and to compare indices of reliability with a chest worn heart rate monitor.</p> Methods <p>Participants (<i>N</i> = 29; male = 16, female = 13; age: 15.8 ± 0.7) completed the 3MST₃₀ on two occasions, in a lab setting (T1) and in a school setting (T2), one week apart. Participants wore a Braun^® FPM and a Polar^® H7 chest strap heart rate monitor. Heart rate in beats per minute (bpm) was recorded on both devices at 1-minute, 2-minutes, 3-minutes, and one minute following test completion. Equivalence testing was used to analyse the data for differences between the two devices by using the TOSTER R package.</p> Results <p>Absolute mean differences between devices and settings were clinically insignificant, with the smallest variance at the 1-minute post recording (FPM <i>p</i> = .012; chest strap = 0.041). There were no statistically significant differences in heart rate measurement between settings.</p> Conclusions <p>This study demonstrates that finger pulse monitoring is a reliable and valid tool for measuring heart rate during sub-maximal exercise in lab and school settings.</p>