MET Values, RPE, and Heart Rate Zones: How Exercise Scientists Measure Intensity
METs let you compare any physical activity in a single number. Here's the full MET scale with specific values, the calorie calculation formula, RPE scales and the talk test, heart rate zones explained, and why fitness level makes the same workout burn fewer calories over time.
By sadiqbd · June 9, 2026
MET values are how exercise scientists compare the intensity of completely different activities — here's how to actually use them
The MET (Metabolic Equivalent of Task) is the unit that lets you compare a gym session to a walk to a bike ride to housework in one number. One MET = resting metabolic rate (approximately 3.5ml of oxygen per kg per minute). An activity with a MET of 4 requires 4× the energy of sitting still.
The Compendium of Physical Activities (Ainsworth et al.) catalogues over 800 activities with their MET values, and this database underlies the calorie estimates in fitness trackers, medical exercise prescriptions, and public health guidelines.
How to read the MET scale
| MET range | Intensity | Examples |
|---|---|---|
| 1.0–1.5 | Sedentary | Sitting, watching TV, light deskwork |
| 1.5–3.0 | Light activity | Slow walking (< 3 km/h), standing, light stretching |
| 3.0–6.0 | Moderate activity | Brisk walking, leisurely cycling, yoga, household cleaning |
| 6.0–9.0 | Vigorous activity | Running at 9–10 km/h, swimming, singles tennis |
| 9.0–12.0 | Very vigorous | Running at 12–14 km/h, competitive sports, rowing |
| 12.0+ | Maximal/near-maximal | Sprinting, elite athletic competition |
WHO physical activity guidelines define:
- Moderate intensity: 3–6 METs
- Vigorous intensity: ≥ 6 METs
The recommendation of "150 minutes of moderate intensity or 75 minutes of vigorous intensity per week" is directly based on MET thresholds. 75 minutes of vigorous activity (6+ METs) is physiologically equivalent to 150 minutes of moderate activity (3–6 METs) because of the doubled intensity.
Selected MET values from the Compendium
Walking and running:
| Activity | MET |
|---|---|
| Walking 3.2 km/h (slow) | 2.8 |
| Walking 4.8 km/h (moderate) | 3.5 |
| Walking 6.4 km/h (brisk) | 4.3 |
| Jogging 8.0 km/h | 8.3 |
| Running 10.0 km/h | 10.0 |
| Running 12.0 km/h | 11.8 |
| Running 16.0 km/h | 14.5 |
Cycling:
| Activity | MET |
|---|---|
| Leisurely cycling (<16 km/h) | 5.8 |
| Moderate cycling (19–22 km/h) | 8.0 |
| Vigorous cycling (23–26 km/h) | 10.0 |
| Stationary cycling (moderate) | 5.5 |
| Indoor cycling class (high intensity) | 11.5 |
Everyday activities:
| Activity | MET |
|---|---|
| General gardening | 3.5 |
| Mowing lawn (walking mower) | 5.5 |
| Cleaning floors | 3.0 |
| Carrying heavy boxes | 5.0 |
| Grocery shopping | 2.3 |
| Active playing with children | 4.0 |
The calorie calculation
Calories burned = MET × weight (kg) × time (hours)
For a 75kg person walking at 4.8 km/h for 45 minutes: 3.5 × 75 × 0.75 = 197 calories
For the same person running at 10 km/h for 30 minutes: 10.0 × 75 × 0.5 = 375 calories
The running burns nearly twice as many calories in two-thirds the time — reflecting the nearly 3× higher MET value.
RPE: estimating intensity without equipment
The Borg Rate of Perceived Exertion (RPE) scale maps subjective effort to exercise intensity:
Borg 6–20 scale:
| RPE | Effort | Approximate MET range | Can you talk? |
|---|---|---|---|
| 6–7 | No effort | 1–2 | Easily |
| 8–9 | Very light | 2–3 | Easily |
| 10–11 | Light | 3–4 | Easily |
| 12–13 | Somewhat hard | 4–6 | In sentences |
| 14–15 | Hard | 6–8 | Short phrases only |
| 16–17 | Very hard | 8–11 | Difficult |
| 18–20 | Maximal effort | 12+ | Cannot |
The talk test is the simple field version: if you can hold a conversation normally, you're at moderate intensity; if you can only say short phrases, you're at vigorous intensity; if you can't speak at all, you're near maximum.
Heart rate zones and MET relationship
Heart rate zones are another way to prescribe and track exercise intensity. They're expressed as percentages of maximum heart rate (HR max), often estimated as 220 − age.
| Zone | % HR max | RPE (6–20) | Approx MET | Feel |
|---|---|---|---|---|
| Zone 1 (recovery) | 50–60% | 9–11 | 2–4 | Easy, conversational |
| Zone 2 (fat burning/aerobic) | 60–70% | 11–13 | 4–6 | Comfortable, can talk |
| Zone 3 (aerobic) | 70–80% | 13–15 | 6–8 | Somewhat hard, short phrases |
| Zone 4 (lactate threshold) | 80–90% | 15–17 | 8–11 | Hard, can't sustain long |
| Zone 5 (maximum) | 90–100% | 18–20 | 11+ | Maximal, unsustainable |
Zone 2 training has received significant attention in longevity and endurance research as the optimal intensity for building aerobic base: sustainable for long durations, builds mitochondrial density, primarily fat-oxidising, recoverable quickly.
Why fitness level changes calorie burn efficiency
A counterintuitive finding: more aerobically fit people burn fewer calories doing the same exercise at the same absolute intensity.
The mechanism: training improves movement efficiency and cardiovascular efficiency. A trained runner at 10 km/h uses oxygen more efficiently than an untrained runner at the same pace — lower oxygen cost per unit of work. In practical terms: the same workout produces fewer calorie burns as fitness improves.
This is partly why calorie-burning workouts become progressively less effective: you improve at them. The adaptation that makes you a better athlete also reduces the calorie expenditure per workout.
The response to this: increase duration, increase intensity, add variety, or focus on outcomes beyond calorie burn (performance, strength, cardiovascular health).
How to use the Calories Burned Calculator on sadiqbd.com
- Enter your weight
- Select the activity from the dropdown (uses MET values from the Compendium)
- Enter duration
- Read the calorie estimate — use as a directional guide, not a precision measurement (individual variation is ±15–20%)
Most useful applications:
- Comparing two activities to understand relative calorie cost
- Estimating how much additional calorie allowance exercise creates
- Selecting activities that provide good calorie burn per time invested
Frequently Asked Questions
Why does my fitness tracker give different numbers than the calculator? Fitness trackers estimate calories from heart rate, which varies with fitness level, hydration, caffeine, and other factors. The MET formula uses body weight without fitness level adjustment. Both are estimates with significant individual variation — neither is precise.
Is the Calories Burned Calculator free? Yes — completely free, no sign-up required.
MET values turn exercise intensity from an abstract feeling into a comparable number. Understanding where different activities fall on the scale makes it practical to mix and match workouts while knowing their relative physiological demands.
Try the Calories Burned Calculator free at sadiqbd.com — get MET-based calorie estimates for over 100 activities by weight and duration.
