MET Values and Exercise Calorie Calculation Formula
Core Conclusion
1 MET = resting oxygen uptake of 3.5 mL O₂/kg/min. Calories = MET × kg × hours. MET values are cataloged in the 2011 Compendium of Physical Activities (Ainsworth et al., PubMed ID 21681120), with the original 1993 (PMID 8306190) and 2000 (PMID 10902700) editions providing historical continuity.
Physical activity energy expenditure is one of the most heterogeneous and difficult-to-measure components of daily energy balance. Across the span of a day, a single person transitions between seated rest, household tasks, commuting, walking, and potentially structured recreational movement, each with a different metabolic rate. The MET (metabolic equivalent of task) system was developed specifically to provide a standardized, population-level reference scale for comparing the relative energy intensity of these diverse activities. This page documents the formal definition of 1 MET, traces its origins through 20th-century calorimetry research, derives the calorie calculation formula from first thermodynamic principles, explains the hierarchical code structure of the Compendium of Physical Activities, provides a 20-activity MET reference table, and illustrates the calculation with worked numerical examples.
Activity-specific calorie expenditure calculations based on the 2011 Compendium MET values are implemented in the [Exercise Calorie Burn + ../tools/exercise-calorie-calculator.html]. Daily total energy expenditure, which combines resting metabolism with the MET-based activity contributions, is computed in the [TDEE Calculator + ../tools/tdee-calculator.html]. Reference caloric density values for common foods, which form the intake side of the energy balance equation, are available in the [Food Calorie Table + ../tools/food-calorie-table.html].
MET Definition and Intellectual History
The concept of a standardized resting metabolic reference originates in the direct and indirect calorimetry studies of W.O. Atwater and F.G. Benedict conducted in the first decades of the twentieth century. Atwater and Benedict's 1905 publication on the metabolism of rest and work established that adult resting oxygen consumption clustered around a stable value of roughly 3.5 milliliters of oxygen per kilogram of body mass per minute when measured by indirect calorimetry in seated, post-absorptive adults[Atwater-Benedict 1905].
This resting reference value was adopted as the 1 MET anchor by exercise physiologists through the middle of the twentieth century, but the systematic compilation of MET values for hundreds of specific activities did not occur until the early 1990s. The first formal Compendium of Physical Activities was published in 1993 by Barbara E. Ainsworth, William L. Haskell, Arthur S. Leon, David R. Jacobs, and colleagues in the journal Medicine & Science in Sports & Exercise (PubMed ID 8306190). The 1993 Compendium cataloged approximately 450 activity codes, each with an assigned MET value derived from published indirect calorimetry studies or expert consensus judgment[Ainsworth 1993].
Subsequent editions expanded the catalog and revised values. The 2000 update (PubMed ID 10902700) expanded the code list and incorporated new published measurement data. The 2011 Compendium (PubMed ID 21681120) is the most widely cited edition in current use, cataloging more than 800 activity-specific MET codes across 21 major categories. A further updated edition was published in 2024. All editions retain the same core definition of 1 MET as 3.5 mL O₂/kg/min[Ainsworth 2000, Ainsworth 2011].
Derivation: The Full Thermodynamic Chain from Oxygen to Calories
The simplified field formula Calories = MET × kg × hours is the terminal result of a chain of unit conversions and approximations that begins with the definition of a MET as an oxygen consumption rate. The full derivation is presented below for reference. The respiratory quotient (RQ) — the ratio of carbon dioxide produced to oxygen consumed — enters the chain via the caloric equivalent of oxygen.
Step 1 — MET to Oxygen Consumption Rate
By definition: 1 MET = 3.5 mL O₂ per kg of body mass per minute
Therefore, for a specific activity with MET value M and a person of weight W kilograms:
V̇O₂ (mL/kg/min) = M × 3.5
V̇O₂ total (mL/min) = M × 3.5 × W
Step 2 — Respiratory Quotient and the Caloric Equivalent of Oxygen
Each liter of oxygen consumed in human metabolism releases approximately 4.825 kilocalories of energy at a mixed-substrate respiratory quotient (RQ) of 0.85, which is the typical average for a mixed-fuel (carbohydrate, fat, protein) metabolic state. This value is the caloric equivalent of oxygen. The caloric equivalent ranges from 4.686 kcal/L at pure fat oxidation (RQ 0.7) to 5.047 kcal/L at pure carbohydrate oxidation (RQ 1.0), with 4.825 kcal/L at RQ 0.85 used as the population average approximation in MET calorie calculations.
Step 3 — Unit Conversion and the 1 kcal/MET-kg-hour Approximation
Total energy = V̇O₂ (L/hr) × 4.825 (kcal/L O₂)
V̇O₂ (L/hr) = M × 3.5 (mL/kg/min) × W (kg) × 60 (min/hr) ÷ 1000 (mL/L)
V̇O₂ (L/hr) = M × W × 0.21
Total energy = M × W × 0.21 × 4.825 = M × W × 1.01325 ≈ M × W × 1.0
The product 3.5 × 60 × 4.825 ÷ 1000 evaluates to approximately 1.01325, which rounds to the field-friendly approximation of 1.0. The simplified working formula is therefore:
Calories = MET × weightkg × durationhours
The small discrepancy between the 1.01325 precise conversion factor and the 1.0 approximation is one source of systematic difference between MET-estimated calories and indirect calorimetry measurements, alongside inter-individual variation in movement economy and fitness.
Compendium of Physical Activities Code Structure
Activities in the Compendium are organized into a hierarchical coding system using 5-digit numeric codes, where the first two digits identify the major category and the remaining three digits identify the specific activity within that category. The 2011 Compendium includes 21 major categories. Eight of the most frequently referenced categories are listed below with three representative example activity codes each[Ainsworth 2011].
Category 01000 — Bicycling
- 01012 — Bicycling, general, to work or for pleasure — 6.8 MET
- 01010 — Bicycling, <16 km/h (10 mph), leisure, to work or for pleasure — 4.0 MET
- 01017 — Bicycling, 25.7–29 km/h (16–18 mph), racing or fast, drafting — 11.0 MET
Category 02000 — Conditioning Exercise
- 02041 — Exercise (calisthenics), general, moderate effort — 3.8 MET
- 02010 — Resistance (weight) training, free weights, universal or Nautilus machines, general — 3.5 MET
- 02024 — Stair stepper machine, general — 8.0 MET
Category 03000 — Home Activities
- 03010 — Cleaning, general (dusting, straightening up, changing linen, carrying out trash) — 3.0 MET
- 03018 — Mopping, kitchen or any other room — 3.5 MET
- 03040 — Scrubbing floors, on hands and knees — 3.5 MET
Category 05000 — Home & Yard Work (Lawn and Garden)
- 05010 — Planting seedlings, shrub cuttings — 3.0 MET
- 05020 — Gardening, general — 3.6 MET
- 05040 — Digging, spading, filling garden, composting — 5.0 MET
Category 06000 — Miscellaneous Activities
- 06010 — Occupation, sitting with light effort (writing, desk work, using computer, typing) — 1.5 MET
- 06021 — Standing, light effort (filing, talking, assembling small parts) — 2.0 MET
- 06040 — Walking, using crutches — 5.0 MET
Category 07000 — Running
- 07010 — Running, general — 8.0 MET
- 07020 — Running, 8 km/h (5 mph) — 8.3 MET
- 07030 — Running, 9.6 km/h (6 mph) — 9.8 MET
Category 10000 — Sports
- 10060 — Basketball, general — 6.5 MET
- 10140 — Soccer, general — 7.0 MET
- 10180 — Tennis, general — 7.3 MET
Category 17000 — Walking
- 17010 — Walking, general — 3.5 MET
- 17020 — Walking for exercise, 5.6 km/h (3.5 mph) — 4.3 MET
- 17040 — Walking, 7.2 km/h (4.5 mph) — 5.5 MET
Standard MET Reference Table — 20 Common Activities (2011 Compendium Values)
The following table lists the 2011 Compendium MET values for 20 frequently referenced activities. MET values in the Compendium are typically reported to one decimal place. Multiple specific subcodes may exist for a given activity depending on intensity or pace; the general-code value is shown here.
| Activity Description | Compendium Code | 2011 MET Value | Intensity Band |
|---|---|---|---|
| Sleeping | 06000 | 0.9 | Sedentary |
| Sitting quietly, watching TV | 06001 | 1.3 | Sedentary |
| Desk work, seated, typing, writing | 06010 | 1.5 | Sedentary |
| Standing, light effort | 06021 | 2.0 | Light |
| Cooking / food preparation | 03060 | 2.1 | Light |
| Cleaning general (dusting, straightening) | 03010 | 3.0 | Moderate |
| Walking slow, flat, 4.8 km/h (3 mph) | 17015 | 3.0 | Moderate |
| Calisthenics, home, general moderate | 02041 | 3.8 | Moderate |
| Walking for exercise, 5.6 km/h (3.5 mph) | 17020 | 4.3 | Moderate |
| Bicycling leisurely, <10 mph | 01010 | 4.0 | Moderate |
| Weight training (resistance), general | 02010 | 3.5 | Moderate |
| Gardening, general | 05020 | 3.6 | Moderate |
| Walking brisk, 7.2 km/h (4.5 mph) | 17040 | 5.5 | Moderate |
| Digging, spading, gardening | 05040 | 5.0 | Moderate |
| Basketball, general, casual game | 10060 | 6.5 | Vigorous |
| Soccer, general, casual game | 10140 | 7.0 | Vigorous |
| Running general (8.3 kph / 5 mph) | 07020 | 8.3 | Vigorous |
| Swimming laps, freestyle, moderate | 18060 | 8.0 | Vigorous |
| Tennis singles general | 10180 | 7.3 | Vigorous |
| Stair climbing machine, general | 02024 | 8.0 | Vigorous |
Intensity Classification by MET Bands (Ainsworth Coding Convention)
The Compendium of Physical Activities defines four standard intensity classification bands based on MET value thresholds. These bands are used consistently in public health surveillance reports, epidemiology studies, and physical activity questionnaire coding. The boundaries are as follows[Ainsworth 2011]:
| Intensity Classification | MET Value Range | Representative Examples |
|---|---|---|
| Sedentary or Resting | ≤ 1.5 MET | Sleeping, reclining, seated desk work, watching television |
| Light Intensity | 1.6 – 2.9 MET | Standing light work, slow walking indoors, food preparation, washing dishes |
| Moderate Intensity | 3.0 – 5.9 MET | Brisk walking, household cleaning, gardening, bicycling leisure pace, weight training |
| Vigorous Intensity | ≥ 6.0 MET | Running, swimming laps, singles tennis, team sports play, stair climbing machine |
Formula Worked Examples for a 70 kg Person, 30 Minutes Duration Each
Example 1 — Walking at 3.0 MET (leisurely 4.8 km/h flat)
Duration in hours = 30 min ÷ 60 = 0.5 hours
Calories = MET × kg × hours = 3.0 × 70 × 0.5 = 105 kilocalories
Example 2 — Jogging at 7.0 MET (running general pace)
Duration in hours = 0.5 hours
Calories = 7.0 × 70 × 0.5 = 245 kilocalories
Example 3 — Swimming at 8.0 MET (freestyle laps moderate)
Duration in hours = 0.5 hours
Calories = 8.0 × 70 × 0.5 = 280 kilocalories
Limitations: Inter-Individual Variability and Movement Economy
MET values are population reference averages, not individual measurements. The Compendium editors explicitly note that MET values in the catalog carry typical uncertainty of approximately ±10 to ±20 percent for any given individual, depending on fitness level, movement technique, body composition, and environmental conditions.
Two individuals performing the same nominal activity can expend substantially different amounts of energy due to differences in movement economy. A trained runner, for example, uses less oxygen per kilogram at a given running speed than a less-trained runner, meaning the same 8.3 MET code for 5 mph running represents an average that both underestimates and overestimates individuals depending on their position in the fitness distribution.
Terrain, wind, temperature, equipment weight, and footwear also contribute to variance between MET-estimated and measured expenditure. The MET system is designed for population-level classification and comparison; for precise individual measurement, direct or indirect calorimetry remains the reference standard.