Anaerobic Threshold Calculator — AT Heart Rate & Training Zones
Estimate the heart rate at which your body crosses from aerobic to anaerobic metabolism. Enter your age and resting heart rate to get your estimated HRmax, anaerobic threshold (AT) heart rate, and five training zones — without a lab test.
years
bpm
HRmax formula
Estimated AT zone: 163–175 bpm (80–90% HRR)
- 1
Max heart rate (Tanaka)
208 − 0.7 × 30 = 187Tanaka et al. 2001 — validated on 500+ subjects, more accurate above age 40. - 2
Heart rate reserve (HRR)
187 − 65 (HRrest) = 122 - 3
Anaerobic threshold heart rate
65 + 0.85 × 122 = 169
How does this calculator work?
The anaerobic threshold is estimated as HRrest + 0.85 × (HRmax − HRrest), where HRmax ≈ 208 − 0.7 × age (Tanaka). For a 30-year-old with a resting HR of 65 bpm: HRmax ≈ 187, HRR = 122, AT ≈ 169 bpm. Train in the 80–90% HRR band to improve threshold fitness.
Formula
How this is calculated
The anaerobic threshold (AT) — also called the lactate threshold or ventilatory threshold — is the exercise intensity above which lactic acid accumulates in the blood faster than it can be cleared. Below AT you can sustain effort for hours; above it, fatigue builds quickly. Accurate AT measurement requires a supervised incremental exercise test with blood-lactate sampling or expired-gas analysis, but population-based formulas give a useful training estimate.
This calculator uses the Tanaka formula (HRmax = 208 − 0.7 × age), which was validated on over 500 subjects and is more accurate than the classic 220 − age formula especially above age 40. The Karvonen method then expresses AT as a percentage of the Heart Rate Reserve (HRR = HRmax − HRrest): research suggests AT typically falls between 80–90% of HRR, with the midpoint (85%) used as the primary estimate.
The five training zones derived from HRmax give you actionable intensity bands: Zone 1 (recovery), Zone 2 (aerobic base-building), Zone 3 (aerobic tempo), Zone 4 (threshold, centred on AT), and Zone 5 (anaerobic). The AT zone (80–90% HRR) overlaps Zone 4 and the lower part of Zone 5. Note that individual variation is large — athletes with a high aerobic base often have an AT closer to 90% of HRmax, while deconditioned individuals may hit AT as low as 70%.
Frequently asked questions
Below AT you can hold a conversation and sustain effort indefinitely. At AT you can speak short sentences but maintaining pace is uncomfortable for more than 30–60 minutes. Above AT, speaking full sentences is difficult and effort is sustainable for only a few minutes. Using a heart rate monitor with your estimated AT zone makes this precise.
The Tanaka formula has a standard deviation of about ±7 bpm, so your actual HRmax could be anywhere from roughly −14 to +14 bpm of the estimate with 95% confidence. A direct measurement (supervised maximal-effort test) is always more accurate. Do not attempt a maximal effort test without medical clearance if you have cardiovascular risk factors.
A lower resting heart rate means a larger Heart Rate Reserve, which shifts the absolute AT heart rate upward even if the percentage stays the same. Well-trained athletes may have a resting HR of 40–50 bpm and a correspondingly wide range of useful training intensities. If you measure resting HR immediately after waking (before standing), you get the most stable value.
TG we-Calculate Editorial Team. (2026). Anaerobic Threshold Calculator — AT Heart Rate & Training Zones [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/anaerobic-threshold-calculator
TG we-Calculate Editorial Team. "Anaerobic Threshold Calculator — AT Heart Rate & Training Zones." TG we-Calculate. 2026. https://we-calculate.com/calculator/anaerobic-threshold-calculator.
TG we-Calculate Editorial Team, "Anaerobic Threshold Calculator — AT Heart Rate & Training Zones," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/anaerobic-threshold-calculator
@misc{wecalculate_anaerobic_threshold_calculator, title = {Anaerobic Threshold Calculator — AT Heart Rate & Training Zones}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/anaerobic-threshold-calculator}}, year = {2026}, note = {TG we-Calculate} }
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