Heart Rate Training Card
Your zones in beats, the formulas behind them, and the one rule most people break every session.
BFCBrilliance · bfcbrilliance.com/tools/heart-rate-zone-calculator
Your numbers
- Age
- Resting HR
- Date measured
- Max HR (Tanaka)
- Heart rate reserve
- EASY from
- EASY to
- HARD from
- HARD to
Log the sessions — was it actually easy?
| Date | Session | Avg HR | In the easy range? | How it felt |
|---|---|---|---|---|
The formulas
- Tanaka max HR
- 208 - 0.7 x age (used here)
- Fox max HR
- 220 - age (the old one)
- They cross at
- exactly age 40
- Under 40
- 220-age reads HIGH
- Over 40
- 220-age reads LOW — by ~9 bpm at 70
- Heart rate reserve
- max - resting
- Karvonen zone
- resting + % x reserve
- ⚠ Margin of error
- ±10-15 bpm on ANY age formula
The zones, as % of reserve
- 50-60%
- recovery
- 60-70%
- EASY / aerobic base — most of your week
- 70-80%
- steady / tempo
- 80-90%
- threshold and intervals
- 90-100%
- maximal — a small share, if any
Getting the inputs right
- Resting HR measured on WAKING, lying still - not at a desk
- Taken across several mornings, lowest sensible value used
- Re-measured every few months - it moves as fitness changes
- A separate max noted per sport if you train in more than one
- Zones sense-checked against feel, not obeyed blindly
- Easy sessions checked against the conversation test
- Heat, altitude, illness and caffeine all shift heart rate — expect it
The conversation test beats the watch
If you cannot speak in full sentences, you are not in the easy range whatever the strap says. Heart rate drifts upward through a long session, lags behind effort at the start, and is thrown off by heat, caffeine, sleep and stress. The number is a useful check on your judgement, not a replacement for it.
Not medical advice
These are estimates from population formulas with a margin of error wider than a zone. They are not a clinical assessment and take no account of medication - beta blockers in particular lower both resting and maximum heart rate substantially, making age-predicted zones meaningless. If you have a heart condition, are on medication affecting heart rate, or are new to hard exercise, speak to a doctor before training to any prescribed intensity.