Calculating Heart Rate Zones
If you don’t train with a power meter, a heart rate monitor is an effective tool for measuring workout intensity. To calculate your training zones, you’ll need two key numbers: your maximum heart rate (HRmax) and resting heart rate (HRrest).
Determining Your Heart Rate Values
Resting Heart Rate (HRrest):
Measure your pulse each morning for three to five days, then take the average.Maximum Heart Rate (HRmax):
A simple estimate is 220 minus your age. While other methods may provide more accuracy, this is a reliable starting point.
You can also record your highest heart rate during an intense training session with hard intervals — often close to your lactate threshold, which is typically about 85% of HRmax.
Heart Rate Reserve Formula
Once you have both your resting and maximum heart rate, use this formula to determine your target heart rate as a percentage of effort:
HRmax – HRrest = HRreserve
(HRreserve × target%) + HRrest = Target HR
Example:
HRmax: 180
HRrest: 50
| Target % | Calculation | Target HR |
|---|---|---|
| 50% | (130 × 0.5) + 50 | 115 bpm |
| 60% | (130 × 0.6) + 50 | 128 bpm |
| 70% | (130 × 0.7) + 50 | 141 bpm |
| 80% | (130 × 0.8) + 50 | 154 bpm |
| 90% | (130 × 0.9) + 50 | 167 bpm |
Zones:
115–127 bpm
128–140 bpm
141–153 bpm
154–166 bpm
167+ bpm
Simplified Heart Rate Training Zones
A simpler method (based on a percentage of HRmax) is often easier to apply:
| Zone | % of HRmax | Purpose |
|---|---|---|
| 1 | 60–68% | Warm-up, recovery rides |
| 2 | 68–76% | Endurance and base training |
| 3 | 76–84% | Aerobic rides lasting several hours |
| 4 | 84–91% | Lactate threshold efforts (5 min – 1 hr) |
| 5 | 91%+ | Short, high-power efforts (10 sec – 3 min) |
Lactate Threshold Zones
If you know your heart rate at lactate threshold (LTHR) — the highest effort you can sustain for about an hour (usually 85–93% of HRmax) — you can set even more accurate zones:
| Zone | % of LTHR |
|---|---|
| 1 | 65–75% |
| 2 | 75–85% |
| 3 | 85–95% |
| 4 | 95–105% |
| 5 | 105%+ |
Note: Heart rate zones vary between individuals. Accuracy depends on your HRmax and HRrest, both of which can change with training, health, and age.
Wattage Zones (Based on 2×8-Minute Field Test Average)
Assume 100% = Field Test Average Power
| Type | % of Field Test |
|---|---|
| Power Intervals | 100%+ |
| Time Trial | 95–100% |
| Steady State | 85–90% |
| Tempo | 80–84% |
| Endurance Miles | 45–75% |
| Recovery Miles | <45% |
Indoor/Outdoor Conversion
| Zone | Indoor % | Outdoor % |
|---|
| Power Intervals | 90%+ | 100%+ |
| Time Trial | 84–90% | 95–100% |
| Steady State | 76–80% | 85–95% |
| Tempo | 70–75% | 80–85% |
| Endurance Miles | 40–66% | 45–75% |
Critical Power Calculation
Perform two all-out efforts: one for 3 minutes and another for 20 minutes.
Multiply average watts by duration (in seconds) for each:
3 min avg watts × 180 sec = Joules (3-min effort)
20 min avg watts × 1200 sec = Joules (20-min effort)
Subtract the two totals, then divide by the difference in seconds:
(Joules₍20min₎ – Joules₍3min₎) ÷ (1200 – 180) = FTP
Example:
3 min × 390 = 70,200
20 min × 330 = 396,000
396,000 – 70,200 = 325,800 ÷ 1020 = 319 watts FTP