The Karvonen formula (Heart Rate Reserve method) is the gold standard for calculating personalized training zones because it accounts for your individual fitness level via your Resting Heart Rate (RHR).

Standard vs. Karvonen

The simple formula (220 – age) gives the same zones to a 30-year-old couch potato and an elite marathon runner of the same age. The Karvonen method fixes this: a trained athlete with an RHR of 45 BPM will get meaningfully different zones than a sedentary person with an RHR of 75 BPM.

Formulas

• MHR = 220 – Age
• HRR = MHR – Resting HR
• Target HR = (HRR × Intensity%) + Resting HR

The 5 Zones

• Zone 1 (50–60%): Warm-up / active recovery
• Zone 2 (60–70%): Fat oxidation, aerobic base, mitochondrial health
• Zone 3 (70–80%): Aerobic capacity and cardiovascular conditioning
• Zone 4 (80–90%): Lactate threshold training
• Zone 5 (90–100%): VO₂ Max intervals — maximum effort

Medical disclaimer: Consult a physician before starting any new exercise program, especially if you have cardiovascular conditions or are over 40 and sedentary.