What is Zone 2 heart rate training?

Zone 2 is the aerobic base zone where you work at 60–70% of your maximum heart rate. At this intensity you can hold a conversation but your breathing is slightly elevated. Zone 2 training primarily burns fat for fuel, improves mitochondrial density, and builds long-term aerobic endurance. For a 40-year-old with a max HR of 180 bpm, Zone 2 is roughly 108–126 bpm.

How do I calculate my maximum heart rate?

The most common formula is: Maximum Heart Rate = 220 − age. For example, a 35-year-old has an estimated max HR of 220 − 35 = 185 bpm. A more accurate formula (Tanaka) is: 208 − (0.7 × age). Both are estimates; a laboratory VO2 max test gives the most precise result.

What heart rate is considered cardio?

Cardio exercise is generally defined as working at 50–85% of your maximum heart rate. Moderate cardio (Zone 3) sits at 70–80% of max HR, which is roughly 126–144 bpm for a 40-year-old. Vigorous cardio (Zone 4, lactate threshold) is 80–90% of max HR. Any sustained aerobic effort above 50% max HR qualifies as cardiovascular exercise.

Heart Rate Training Zones: BPM Ranges by Age & Zone System Explained

The Maximum Heart Rate Formula

All heart rate zones are expressed as a percentage of your maximum heart rate (MHR). The standard formula used by most fitness guidelines is:

Max HR (bpm) = 220 − age

So a 30-year-old has an estimated max HR of 190 bpm, while a 50-year-old has an estimated 170 bpm. The Tanaka formula (208 − 0.7 × age) is slightly more accurate for older adults. These are population averages — individual max HR can vary by ±10–12 bpm.

5-Zone Heart Rate System

The 5-zone model is the most widely used framework in endurance sports and general fitness. Each zone targets a different physiological adaptation.

Zone	Name	% of Max HR	Description
Zone 1	Recovery	50–60%	Very light effort; active recovery, warm-up/cool-down
Zone 2	Fat Burn / Base	60–70%	Conversational pace; primary fuel is fat; builds aerobic base
Zone 3	Aerobic	70–80%	Moderate effort; improves cardiovascular efficiency
Zone 4	Lactate Threshold	80–90%	Hard effort; improves speed and lactate clearance
Zone 5	VO2 Max	90–100%	Maximum effort; brief intervals; increases aerobic ceiling

BPM Targets by Age

The table below applies the 220 − age formula and shows the BPM range for each zone across common ages. Use these as starting points and adjust based on your perceived exertion and fitness level.

Zone	% Max HR	Age 20 (MHR 200)	Age 30 (MHR 190)	Age 40 (MHR 180)	Age 50 (MHR 170)	Age 60 (MHR 160)
Zone 1	50–60%	100–120	95–114	90–108	85–102	80–96
Zone 2	60–70%	120–140	114–133	108–126	102–119	96–112
Zone 3	70–80%	140–160	133–152	126–144	119–136	112–128
Zone 4	80–90%	160–180	152–171	144–162	136–153	128–144
Zone 5	90–100%	180–200	171–190	162–180	153–170	144–160

Choosing the Right Zone for Your Goal

Weight loss: Spend most training time in Zone 2. Fat is the primary fuel source, and you can sustain it long enough to create a meaningful calorie deficit.
Aerobic base: Zone 2 and Zone 3 sessions build the cardiovascular foundation for any sport.
Race performance: Zone 4 intervals improve your lactate threshold — the pace you can sustain for 30–60 minutes.
Peak speed: Zone 5 efforts are short (30 seconds to 3 minutes) and infrequent — typically once per week at most.

Using a Heart Rate Monitor

Chest strap monitors are the most accurate option for real-time zone training. Optical wrist monitors (smartwatches) are convenient but may lag 5–15 seconds during fast intensity changes. Either device is adequate for steady-state Zone 2 and Zone 3 work. For precise lactate-threshold intervals, a chest strap is preferred.

Use our speed converter to cross-reference pace and heart rate data from your GPS watch, and our BMI calculator to get additional health context.