When we speak of calories burned “while doing nothing,” we are talking about the fundamental energy required by a child’s body simply to stay alive: breathing, circulating blood, building cells, and supporting organ function. This foundational process is called Resting Energy Expenditure (REE) or Basal Metabolic Rate (BMR). For children, resting calorie requirements are even more important than in adults, fueling not just maintenance but rapid growth and development.
Resting Calories Burned Calculator
for Kids
Values are “resting” (lying still, not digesting, not sleeping).
This in-depth guide covers the science of children’s resting calorie burn, age-related needs, calculation methods, physiological factors, and practical tips for parents and caregivers—complete with more than five essential reference tables.
Table of Contents
- Introduction: What Are Resting Calories?
- Why Resting Energy Is Critical for Kids
- How Resting Calorie Burn Changes With Age
- Key Factors That Influence Children’s BMR
- Scientific Models: Equations for Kids’ Resting Calories
- Tables: Age, Weight, Sex, and REE
- Babies, Toddlers, School-Age, Teens: Life Stage Considerations
- BMR in Special Situations (Illness, Body Type, Activity)
- How Parents and Clinicians Can Use BMR
- Maximizing Healthy Growth: Nutritional and Lifestyle Tips
- Myths and FAQs About Kids’ Resting Energy Needs
- Summary Tables for Quick Reference
1. Introduction: What Are Resting Calories?
Resting calories represent energy burned by the body at rest—lying still, not digesting, and in a comfortable environment. This is the energy needed just to support vital functions. For children, this makes up the majority (up to 70–80%) of total calories burned daily.
- BMR (Basal Metabolic Rate): Gold-standard for fasted, morning, complete rest.
- RMR (Resting Metabolic Rate): Slightly higher; practical for real-world estimates.
- REE (Resting Energy Expenditure): Nearly synonymous with RMR/BMR.
2. Why Resting Energy Is Critical for Kids
- Growth and Development: Kids burn more resting calories per kg than adults due to rapid cell division, tissue development, and organ maturation.
- Brain Demands: The brain consumes up to 50% of infants’ resting calories.
- Maintenance: Heart, lungs, kidney function, temperature regulation, and building strong immune systems all rely on baseline energy.
3. How Resting Calorie Burn Changes With Age
Children have a much higher resting energy expenditure per body mass compared to adults. This ratio peaks in infancy and gradually decreases into adolescence and adulthood.
- Infant (0–1 year): 50–60 kcal/kg/day resting expenditure
- Toddler (1–3 years): > 50 kcal/kg/day
- Child (4–10 years): 30–40 kcal/kg/day
- Teen (11–18 years): Declining to adult levels, about 25–30 kcal/kg/day
Table 1: Average Resting Calories Burned Per Kilogram by Age
| Age Range | Resting Calories Burned (kcal/kg/day) |
|---|---|
| 0–1 year | 50–55 |
| 2–3 years | 53–55 |
| 4–9 years | 35–45 |
| 10–13 years | 30–37 |
| 14–18 years | 25–30 |
Data adapted from peer-reviewed comparative physiology studies.
4. Key Factors That Influence Children’s BMR
Numerous biological and environmental factors determine each child’s resting calorie requirements:
| Factor | Influence on BMR |
|---|---|
| Weight | Heavier children burn more calories, even at rest |
| Body Composition | Muscle tissue burns more than fat, even for kids |
| Height | Taller children, for their age, often have higher BMR |
| Sex | Boys tend to have more muscle, slightly higher BMR after ~10 years |
| Age | BMR highest per kg at infancy, declines with age |
| Growth Spurts | Periods of rapid growth spike resting calorie needs |
| Puberty | Increases in muscle and hormone shifts raise calorie burn |
| Genetics | Natural “faster” or “slower” metabolisms |
| Health/Illness | Fever/infection increase BMR; hypothyroidism lowers it |
| Environment | Hot/cold climates can slightly raise BMR |
5. Scientific Models: Equations for Kids’ Resting Calories
A. WHO/FAO/UNU Equations
Widely used for clinical and nutritional planning:
Boys 3–10 years:
BMR (kcal/day) = 22.7 × weight (kg) + 495
Girls 3–10 years:
BMR (kcal/day) = 22.5 × weight (kg) + 499
Infants (0–3 years):
BMR (kcal/day) = 60.9 × weight (kg) – 54
B. Schofield and Oxford Equations
Validated by large datasets for estimating BMR in healthy children.
Schofield (3–10 years):
Boys: (22.7 × Weight) + 495
Girls: (22.5 × Weight) + 499
Oxford (10–18 years):
Boys: (17.7 × Weight) + 657
Girls: (13.4 × Weight) + 693
C. Per-Kilogram Formula
A simple practical approach:
- Infants: 50–60 kcal × weight (kg)
- Children/Teens: 25–35 kcal × weight (kg), depending on age and maturity
Table 2: Sample Calculated BMR for Boys and Girls
| Age (yrs) | Weight (kg) | BMR Boys (kcal/day) | BMR Girls (kcal/day) |
|---|---|---|---|
| 1 | 10 | 555 | 545 |
| 5 | 20 | 949 | 949 |
| 10 | 32 | 1,218 | 1,219 |
| 14 | 50 | 1,542 | 1,369 |
| 17 | 65 | 1,812 | 1,563 |
Calculated using Schofield/Oxford equations.
6. Tables: Age, Weight, Sex, and REE
Table 3: Estimated Daily Resting/Basal Calorie Needs by Age and Sex
| Age (yrs) | Boys (kcal/day) | Girls (kcal/day) |
|---|---|---|
| 1–3 | 900–1,100 | 850–1,000 |
| 4–6 | 1,100–1,350 | 1,000–1,250 |
| 7–9 | 1,300–1,600 | 1,200–1,400 |
| 10–12 | 1,500–1,850 | 1,300–1,600 |
| 13–15 | 1,700–2,000 | 1,400–1,700 |
| 16–18 | 1,800–2,250 | 1,500–1,800 |
Values rounded, represent resting needs; total daily needs are higher accounting for activity.
Table 4: Resting Calorie Needs per Hour by Weight
| Weight (kg) | Child BMR (kcal/hr) |
|---|---|
| 10 | 25–30 |
| 20 | 45–55 |
| 30 | 65–75 |
| 40 | 80–90 |
| 50 | 95–105 |
Calculated using BMR per day divided by 24 hours.
Table 5: Calorie Use by State for Children (per hour, 20 kg child, rounded)
| Activity | Calories/hour |
|---|---|
| Deep sleep | 20–25 |
| Resting/lying down | 28–32 |
| Sitting/quiet play | 32–36 |
| Light fidgeting | 36–42 |
| Homework/reading | 38–45 |
Resting calorie use is the lowest and most “pure” BMR.
Table 6: Declining Resting Caloric Needs Per KG with Age
| Age | Resting kcal/kg/day | Example Child (Body wt) | Total kcal/day |
|---|---|---|---|
| Infant (1 yr) | 53 | 10 kg | 530 |
| Preschool (4) | 43 | 16 kg | 688 |
| School age (10) | 33 | 30 kg | 990 |
| Teen (15) | 28 | 55 kg | 1,540 |
| Older teen (18) | 26 | 65 kg | 1,690 |
Shows that per-kg resting needs decline even as total goes up with growth.
7. Babies, Toddlers, School-Age, Teens: Life Stage Considerations
- Infants: Highest resting energy per kilogram—brain and organ development dominate.
- Toddlers: Still very high BMR as growth surges.
- School-Aged Kids: Resting BMR per kg drops, but activity, height, and muscle mass increase.
- Adolescents/Teens: Resting BMR per kg falls further but total calories rise as weight surges and puberty starts, with muscle/fat ratios shifting toward adult norms.
8. BMR in Special Situations
Illness, Fever, or Stress
- Illness, injury, and fever can increase resting expenditure by 10–30% or more.
- Chronic illnesses, some medications, or severe undernutrition reduce BMR.
Obesity vs. Lean Body Type
- Higher total mass increases overall BMR.
- Higher muscle mass = higher BMR compared to similar-weight but higher-fat kids.
Physical Activity
- Does not affect BMR itself, but greater activity increases Total Daily Energy Expenditure (TDEE).
9. How Parents and Clinicians Can Use BMR
- Growth Monitoring: Persistent deviation from expected BMR may signal a health issue.
- Nutritional Planning: Ensuring intake covers at least BMR plus growth and activity calories.
- Special Situations: Adjusting for fever, chronic conditions, weight gain/loss.
10. Maximizing Healthy Growth: Nutritional and Lifestyle Tips
- Don’t restrict calories unnecessarily: The body needs energy even at rest.
- Prioritize balanced diets: Protein supports muscle and brain; fats are critical in young children.
- Encourage active play: While resting expenditure is high, activity builds muscle, supports BMR.
- Track with growth charts: Proper BMI and weight gain reflect healthy energy use.
- Stay alert to changes: Drastic shifts in appetite or weight warrant medical attention.
11. Myths and FAQs About Kids’ Resting Energy Needs
Q: Can I increase my child’s resting calorie burn?
- Answer: Only modestly—muscle mass (from play/sports), adequate sleep, and free play help. True BMR is mostly determined by genetics, age, and body size.
Q: Do boys and girls have the same BMR?
- Answer: Similar until puberty, then boys’ BMR rises with muscle gains.
Q: Does sleep burn calories?
- Answer: Yes—10–20% less than resting awake, but still substantial.
Q: Can under-eating slow a child’s metabolism?
- Answer: Yes—prolonged calorie deficit can suppress BMR, impact growth.
12. Summary Tables for Quick Reference
| Table | Description |
|---|---|
| 1 | Resting Calories per kg by Age |
| 2 | Calculated BMR by Age, Weight, and Sex |
| 3 | Estimated Resting BMR by Age and Sex (kcal/day) |
| 4 | Resting Calorie Needs per Hour by Weight |
| 5 | Calorie Use by State (Rest, Sleep, Fidgeting) |
| 6 | Declining Resting kcal/kg/day Across Childhood |
Key Takeaways
- Resting calorie burn dominates children’s energy needs, especially in early years.
- Age, weight, body composition, health, and genetics all play a role.
- Accurate calculations help ensure healthy growth, optimal nutrition, and early disease detection.
- Target nutrient-dense diets and foster active lifestyles for robust development.
Always consult with a pediatrician for individual assessment and if there are concerns about growth, nutrition, or metabolism.