You typed your numbers into a BMR calculator and got something like 1,450 or 1,820 calories. Now you want to know one simple thing: is that normal for someone my age?
Most "average BMR" charts online don't say where their numbers come from. Some are copied from other sites. Some mix up BMR with total daily calories. This guide does it the honest way. We take the real average body size of adults in each age group, measured by the CDC, and run it through the same formula your calculator uses. You get a chart you can trust, and you can see every step.
- The average US man has an estimated BMR of about 1,850 kcal/day in his 20s and 30s, falling to about 1,580 kcal/day by his 70s.
- The average US woman has an estimated BMR of about 1,480–1,490 kcal/day in her 20s and 30s, falling to about 1,190 kcal/day by her 70s.
- Age itself is not the main driver before 60. A large 2021 study in Science found that metabolism, adjusted for body size, stays steady from about age 20 to 60.
- Body size and muscle matter more than birthdays. Two people of the same age can be 400+ calories apart.
- "Average" is not "healthy" or "ideal". It just describes the typical adult today.
Average BMR by Age: The Chart
Here are the estimated average BMR values for US adults, by age group and sex. Each number comes from the average measured weight and height for that group in the newest national survey, plugged into the Mifflin-St Jeor equation at the middle age of the group.
| Age group | Avg. man (weight / height) | Est. BMR, men | Avg. woman (weight / height) | Est. BMR, women |
|---|---|---|---|---|
| 20–29 | 86.8 kg / 176.3 cm | ≈ 1,850 kcal | 74.8 kg / 163.5 cm | ≈ 1,484 kcal |
| 30–39 | 91.4 kg / 176.1 cm | ≈ 1,845 kcal | 80.9 kg / 162.5 cm | ≈ 1,489 kcal |
| 40–49 | 95.3 kg / 176.4 cm | ≈ 1,836 kcal | 80.4 kg / 161.7 cm | ≈ 1,429 kcal |
| 50–59 | 92.1 kg / 174.3 cm | ≈ 1,740 kcal | 81.6 kg / 161.2 cm | ≈ 1,388 kcal |
| 60–69 | 89.2 kg / 174.7 cm | ≈ 1,664 kcal | 77.5 kg / 160.5 cm | ≈ 1,292 kcal |
| 70–79 | 87.7 kg / 172.4 cm | ≈ 1,584 kcal | 73.8 kg / 158.3 cm | ≈ 1,191 kcal |
Weights and heights: CDC National Center for Health Statistics, Anthropometric Reference Data for Children and Adults: United States, August 2021–August 2023 (Vital and Health Statistics, Series 3, No. 50), Tables 3 and 7. BMR: our calculation with the Mifflin-St Jeor equation at ages 25, 35, 45, 55, 65 and 75.
Two patterns jump out. First, men sit roughly 350–390 calories above women at every age. Second, the numbers barely move from the 20s to the 40s, then fall step by step after 50.
“Average” describes the typical person in the survey. It does not tell you what is healthy, and it does not tell you what your body burns. — The one rule to keep in mind while reading any BMR chart
Same chart with the older Harris-Benedict formula
Some calculators still use the revised Harris-Benedict equation from 1984. It tends to give higher numbers. Here is the same data run through it, so you can see why two calculators disagree.
| Age group | Men: Mifflin-St Jeor | Men: Harris-Benedict | Women: Mifflin-St Jeor | Women: Harris-Benedict |
|---|---|---|---|---|
| 20–29 | 1,850 | 1,955 | 1,484 | 1,538 |
| 30–39 | 1,845 | 1,959 | 1,489 | 1,548 |
| 40–49 | 1,836 | 1,956 | 1,429 | 1,497 |
| 50–59 | 1,740 | 1,846 | 1,388 | 1,463 |
| 60–69 | 1,664 | 1,753 | 1,292 | 1,380 |
| 70–79 | 1,584 | 1,665 | 1,191 | 1,296 |
The gap is about 50–120 calories a day. That's why you should always compare your result with a chart built on the same formula. Our guide to all five BMR equations explains where each one comes from.
How We Built These Numbers
We want you to be able to check this work. So here is the full method, step by step.
Step 1: Real body measurements, not guesses
The CDC runs the National Health and Nutrition Examination Survey (NHANES). Trained staff measure people with scales and stadiometers. They don't rely on what people report about themselves. The newest report covers August 2021 to August 2023 and includes 8,545 examined people aged 2 and older.
For all adults 20 and over, the CDC's FastStats page lists the average man at 68.9 inches and 199.0 pounds, and the average woman at 63.5 inches and 171.8 pounds. Our age-group values come from the detailed tables in the same report.
Step 2: The Mifflin-St Jeor equation
Mifflin-St Jeor was published in 1990 and is the formula most calculators use today, including ours. It looks like this:
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Example for the average man in his 30s: 10 × 91.4 + 6.25 × 176.1 − 5 × 35 + 5 = 1,845 kcal/day.
Step 3: Middle age of each group
We used the middle of each 10-year range (25, 35, 45 and so on). A 30-year-old would sit about 25 calories higher than our number for the 30–39 row. A 39-year-old would sit about 20 calories lower.
Does BMR Really Drop With Age?
Yes, but not in the way most people think. The chart shows a slow slide. Yet most of that slide comes from changes in body size and body makeup, not from the calendar alone.
What the big 2021 study found
In 2021, a team led by Herman Pontzer pooled data from more than 6,400 people aged 8 days to 95 years, measured with the doubly labeled water method. They published it in Science. Duke University's news release summed up the main finding in plain words:
Metabolism, adjusted for body size, stayed stable from about age 20 to 60, then declined by about 0.7% a year. — Summary of Pontzer et al., Science 2021 (Duke University and Pennington Biomedical news releases)
That means a 45-year-old does not have a "broken" metabolism compared with a 25-year-old of the same size and muscle. The decline is real after 60, and it is gradual.
So why does the chart still fall after 50?
- Lower weight and height in older groups. In the CDC data, average weight peaks in the 40s for men and the 50s for women, then drops. Average height also falls a little.
- The age term in the formula. Mifflin-St Jeor subtracts 5 calories for every year of age. That's a statistical shortcut that captures muscle loss in the people it was built on.
- Less muscle. Muscle burns more at rest than fat does, and most people lose some muscle as they age. Our article on how much muscle really boosts BMR puts honest numbers on this.
| Life stage | What usually happens | What it means for you |
|---|---|---|
| 20s–30s | BMR near its adult peak for your size | Habits you build now protect muscle later |
| 40s–50s | Little change from age alone; weight often rises | Weight gain is usually about intake and activity, not a "slow metabolism" |
| 60s+ | Gradual decline, about 0.7% a year after size adjustment | Strength training and protein matter more than ever |
How to Compare Your Own BMR
Comparing yourself to an average is only useful if you do it fairly. Follow these steps.
- Get your own estimate. Use the free BMR calculator on our home page or follow our step-by-step BMR formula guide.
- Check the formula. Make sure your calculator used Mifflin-St Jeor if you compare with the first chart.
- Find your row. Pick your age group and sex.
- Compare your body size, too. If you're lighter or shorter than the average shown, your BMR should be lower. That's normal, not a problem.
- Look at the gap, not the label. A difference under about 150 calories is small. It's within the normal error of the equation.
Quick rule of thumb
Under Mifflin-St Jeor, every extra kilogram adds 10 calories, every extra centimeter of height adds 6.25 calories, and every extra year takes away 5 calories. So a woman in her 30s who weighs 65 kg instead of 80.9 kg will have a BMR about 159 calories lower than the average shown. Her number is still perfectly healthy.
Why Your BMR May Be Above or Below Average
Formulas only know four things: weight, height, age and sex. Your body knows a lot more. Here are the main reasons a real person differs from the chart.
| Factor | Pushes BMR | Why |
|---|---|---|
| More muscle (lean mass) | Up | Lean tissue is more active at rest than fat tissue |
| Larger body size | Up | More tissue to keep alive and warm |
| Recent strict dieting | Down (a bit) | The body adapts to lower intake; see our article on starvation mode |
| Thyroid conditions | Up or down | Thyroid hormones set much of your resting burn |
| Fever or illness | Up | Your body works harder to fight infection |
| Genetics | Either way | Some people simply run a little warmer or cooler |
Things that matter less than people think
- Cold showers. They add only a small amount. Our cold shower BMR breakdown shows the real numbers.
- "Metabolism-boosting" foods. Spicy food or green tea may nudge burn for a short time, but the effect is tiny next to body size.
- Eating more often. Six small meals don't raise your BMR. The calories you burn digesting food depend on how much you eat, not how often. See our article on the thermic effect of food.
What to Do With Your Number
BMR is only the starting point. It is what you burn lying still. Your full day, called TDEE, adds movement, exercise and digestion on top.
| Activity level | Typical multiplier | Avg. woman, 30s (BMR 1,489) | Avg. man, 30s (BMR 1,845) |
|---|---|---|---|
| Mostly sitting | × 1.2 | ≈ 1,787 kcal | ≈ 2,214 kcal |
| Light exercise 1–3 days/week | × 1.375 | ≈ 2,047 kcal | ≈ 2,537 kcal |
| Moderate exercise 3–5 days/week | × 1.55 | ≈ 2,308 kcal | ≈ 2,860 kcal |
| Hard exercise 6–7 days/week | × 1.725 | ≈ 2,569 kcal | ≈ 3,183 kcal |
Activity multipliers are the common estimates used by most calorie calculators. They are rough guides, not exact values.
A simple plan
- ✅ Work out your BMR, then your TDEE with an honest activity level.
- ✅ To lose weight, eat a little below TDEE, not below BMR for long periods. Our guide Can you eat below your BMR? explains why.
- ✅ Track your weight for 2–3 weeks and adjust. Real results beat any formula.
- ✅ Lift weights 2–3 times a week to protect muscle, especially after 40.
- ✅ Re-calculate after every 4–5 kg of weight change.
For the full math on weight loss, see How many calories should I eat to lose weight? And if a gym test gave you an "RMR" number, our BMR vs RMR guide shows how the two relate.
Your BMR is a starting estimate. The scale, your energy and your strength over the next month tell you the real story. — BmrCalc editorial team
Frequently Asked Questions
What is a normal BMR for a woman?
For the average US woman, the estimated BMR is about 1,480–1,490 calories a day in her 20s and 30s, about 1,390–1,430 in her 40s and 50s, and about 1,190–1,290 after 60. A smaller woman can be well below these numbers and still be completely healthy.
What is a normal BMR for a man?
For the average US man, it's about 1,840–1,850 calories a day from the 20s to the 40s, about 1,740 in the 50s, and about 1,580–1,660 after 60.
At what age does metabolism slow down?
According to the 2021 Pontzer study, metabolism adjusted for body size stays fairly stable from about 20 to 60 and then declines by roughly 0.7% a year. Weight gain in midlife is usually driven by lifestyle, not by a sudden metabolic slowdown.
Is a BMR of 1,200 too low?
Not on its own. For a small or older woman, around 1,200 calories can be a normal BMR. It only becomes a concern if it's far below what the formula predicts for your size, or if you have symptoms like constant tiredness or feeling cold. In that case, talk with a doctor.
Why is my BMR different on every calculator?
Different calculators use different equations. Harris-Benedict usually gives a higher number than Mifflin-St Jeor, by about 50–120 calories for an average adult. Some calculators also add activity and show TDEE instead of BMR.
Can I raise my BMR?
A little. Building muscle is the most reliable way. Eating enough protein and avoiding long, extreme diets also helps protect it. Don't expect huge changes. Most of your BMR is set by your size.
Sources
- Fryar CD, et al. Anthropometric Reference Data for Children and Adults: United States, August 2021–August 2023. Vital Health Stat 3(50). National Center for Health Statistics, 2025. Tables 3 and 7.
- CDC FastStats: Body Measurements (cdc.gov/nchs/fastats/body-measurements.htm).
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241–247.
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005;105(5):775–789.
- Pontzer H, et al. Daily energy expenditure through the human life course. Science. 2021;373(6556):808–812.
- Duke University news release: "Metabolism Changes With Age, Just Not When You Might Think" (August 12, 2021); Harvard Health Blog: "Surprising findings about metabolism and age" (October 8, 2021).
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