About this tool
Not all heart-rate zone calculators agree, because they start from two different questions: how high can your heart actually go, and how much room does it have to work with above its resting baseline? The classic 220 − age formula answers the first with a single, easy-to-remember number, popularized decades ago and still the default on most gym equipment. The Tanaka formula (208 − 0.7 × age) revisits that estimate with more recent research and tends to run a little higher for older adults, narrowing the gap between the population average and how people actually perform.
The Karvonen method then answers the second question, folding your resting heart rate into the calculation instead of ignoring it. Two people with the same max heart rate but very different fitness levels have very different resting rates — a well-conditioned heart beats slower at rest — so their real training reserve, and therefore their real zone boundaries, are not the same. Multiply that heart rate reserve by an intensity percentage and add it back to your resting rate, and you get a target that reflects your own cardiovascular baseline rather than a one-size-fits-all range.
Frequently asked questions
Why do the classic (220-age) and Tanaka formulas give different max heart rates?
The classic 220-minus-age formula was popularized in the 1970s from a fairly small, non-rigorous dataset, while the Tanaka formula (208 - 0.7×age) came from a 2001 meta-analysis of many more studies and is generally considered more accurate, especially for older adults, where the classic formula tends to overestimate max HR. Neither formula is exact for any individual — a real maximal exercise test is the only way to know your true max HR precisely — but Tanaka is the more research-backed default.
What's the best way to measure my resting heart rate accurately?
Measure it first thing in the morning, right after waking up, while you're still lying in bed and before getting up, having coffee, or checking your phone — any of those will raise your heart rate above true resting levels. Count your pulse (wrist or neck) for a full 60 seconds, or use the average from a fitness tracker/heart rate monitor if you have one, and take the measurement across a few consecutive mornings for a more reliable average, since it naturally fluctuates day to day.