Pregnancy Exercise Calculator

Find your safe exercise heart rate zones during pregnancy using the Karvonen formula and ACOG guidelines.

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How Exercise Heart Rate Zones Are Calculated

This calculator uses the Karvonen formula to calculate target heart rate zones based on heart rate reserve (HRR):

THR = ((Max HR − Resting HR) × intensity%) + Resting HR

Maximum heart rate is estimated as 220 − age. Heart rate reserve (HRR) is the difference between max HR and resting HR, representing the heart's working range.

Three zones are calculated: Light (40–55% HRR) for warm-up and low-intensity activity; Moderate (55–70% HRR) the primary recommended zone for pregnant women per ACOG; and Vigorous (70–85% HRR) shown for reference only, appropriate only for previously active women with provider clearance.

Frequently Asked Questions

This calculator provides estimates for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider with questions about your health or your baby's health.

ACOG Committee Opinion on Physical Activity and Exercise During Pregnancy