not intensity. Pace at the same heart rate typically improves 10-20% over a 12-16 week Zone 2 training block. Trust the process and resist the urge to push the pace. For cross-referencing: use the HRV Calculator to monitor whether your Zone 2 training load is producing adaptation or accumulating fatigue. An upward HRV trend over weeks alongside a stable or falling resting HR is the strongest non-lab signal that your aerobic base is developing as intended. ， percentage of max HR when only age is entered. THE FORMULAS Percentage of max HR Max HR = 220 - age (if not entered directly) Zone 2 = Max HR × 60% to Max HR × 70% Karvonen (Heart Rate Reserve) HRR = Max HR - Resting HR Zone 2 Lower = Resting HR + (HRR × 60%) Zone 2 Upper = Resting HR + (HRR × 70%) MAF (Maffetone) MAF Upper = 180 - age (with optional modifier for training history) Zone 2 = (MAF Upper - 10) to MAF Upper MAF modifiers (apply one): Recovering from illness， no illness: +5 New to exercise or returning after break: -10 VO2 Max-based (Swain et al.， Polar) is less reliable than field-test or lab values - treat those as orientation only. WHAT THIS CALCULATOR DOES NOT CAPTURE Zone 2 is physiologically defined by the first lactate threshold (LT1). No heart rate formula can precisely locate your individual LT1 - that requires a laboratory lactate test with blood samples at incremental intensities. The calculator estimates where LT1 is likely to fall based on population-level data and your measured inputs. Individual LT1 can sit anywhere from 55% to 75% of max HR depending on training history， Details WHAT THIS CALCULATOR COMPUTES This calculator estimates your Zone 2 heart rate training range using four validated methods: percentage of max HR， or on medication: -5 Consistent training 2+ years， MAF (Maffetone)，。
so you can use the results across your entire training programme. The recommended method is selected automatically based on what you have entered: VO2 Max-based when VO2 Max is provided， before getting out of bed. Average three consecutive days. Resting HR measured mid-afternoon or after activity will underestimate your true resting rate and push Zone 2 targets higher than they should be. Max HR is optional but recommended. A measured max HR - from a recent lab test， injury， and neuromuscular fatigue. A session that starts within your Zone 2 range may drift above it over 60-90 minutes. On long sessions， or GPS watch at maximum exertion - replaces the 220 - age estimate. If your true max HR is 10 bpm above the formula estimate， resting HR typically falls - which adjusts your Zone 2 range downward slightly in absolute bpm. This is not a problem: your pace at that heart rate will have improved， inputs， you are above it. Most people find true Zone 2 slower than expected. This is normal. The aerobic system adapts to volume and consistency， and measurement conditions every session. A Karvonen Zone 2 calculated with a resting HR of 58 bpm is not directly comparable to one calculated with a resting HR of 63 bpm - even if you are the same person measured on different days. Re-enter your resting HR every 4-6 weeks if you are in active training. As aerobic fitness improves， 1994) Converts % VO2 Max to % HRR using the validated regression: % HRR = 1.12 × (% VO2 Max) - 12.0 At 60% VO2 Max: % HRR = 55.2% At 70% VO2 Max: % HRR = 66.4% Zone 2 Lower = Resting HR + (HRR × 55.2%) Zone 2 Upper = Resting HR + (HRR × 66.4%) Requires resting HR and max HR (measured or estimated) in addition to VO2 Max. WHAT EACH INPUT MEANS Age is used to estimate max HR (220 - age) when no measured value is entered. It is also the sole input for the MAF method. The 220 - age formula has a standard deviation of ±10-12 bpm - entering a measured max HR materially improves accuracy for all HR-based methods. Resting HR is the anchor for the Karvonen and VO2 Max-based methods. Measure it first thing in the morning after at least five minutes lying still， use pace or power as a secondary anchor rather than relying on heart rate alone. Sport specificity is not adjusted. Running Zone 2 heart rates are typically 5-10 bpm higher than cycling at equivalent perceived effort because running recruits more muscle mass. Zones calculated from running max HR are a reasonable starting point for cycling， start with Karvonen using your resting HR. Run or ride at that heart rate and apply the talk test: full sentences without pausing to breathe means you are in Zone 2. If you cannot speak comfortably， Karvonen (heart rate reserve)， and VO2 Max-based. All four results are shown side by side so you can compare where they agree and where they diverge. The primary output is the Zone 2 bpm range from the recommended method for your inputs. The secondary output is a full 5-zone heart rate table， your Zone 2 ceiling shifts up by 6-7 bpm. For athletes who find Zone 2 uncomfortably slow。
all-out race effort， re-run the Zone 2 calculation. A VO2 Max improvement of 3-5 ml/kg/min - achievable over a 12-16 week training block - shifts Zone 2 by 2-4 bpm. Small， a measured max HR often resolves the problem. VO2 Max is optional and unlocks the fourth calculation method. Enter the result from the VO2 Max Calculator or from a lab test. VO2 Max from smartwatch estimates (Garmin， Apple， but worth recalibrating. PRACTICAL STARTING POINT