There are various ways to estimate muscle mass percentage. These include using medical equipment, calculating body fat percentage, and measuring certain areas of the body.
Maintaining a healthy percentage of muscle mass has several benefits, such as reducing the risk of age-related muscle loss.
In this article, we describe what muscle mass percentage is, why it can be useful to know, and how to calculate it.
A note about sex and gender
Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Learn more.
Muscle mass
Muscles primarily help with movement, maintaining posture, and supporting bodily functions.
There are three main types of muscle:
- smooth muscle, which is in the internal organs
- cardiac muscle, the muscle of the heart
- skeletal muscle, which exists throughout the body
The body’s collective muscle tissue forms its muscle mass.
However, in most contexts, the term “muscle mass” specifically refers to skeletal muscle. This is the only type of muscle that a person can voluntarily control.
Skeletal muscle plays a key role in movement. For example, bending the arm upward requires the bicep muscle to contract and the triceps to relax. Exercising the skeletal muscles in various ways can increase the body’s mobility, balance, and strength.
Keeping the skeletal muscles healthy is important for daily functioning. This may be particularly important for older adults.
Learn more about the different muscle types.
It is possible to determine how much of a person’s body is made up of muscle, fat, and other components.
The most accurate ways involve expensive medical equipment. For example, it is possible to calculate muscle mass percentage from an MRI scan.
However, it is also possible to estimate muscle mass percentage at home. While many online calculators and tools claim to do this, it is unclear whether any of these methods are accurate.
Most rely on calculating body fat percentage. Subtracting this percentage from 100
While lean body mass includes muscle mass, it also includes bone and other components of the body.
There are several ways to determine body fat percentage at home. For example, a person can use a body fat scale, which calculates the amount of fat by sending an electrical current through the body.
The United States Navy recommends a different method, which involves measuring the circumferences of various body parts. These add up to a certain value, and different values and heights represent various body fat percentages.
Muscle mass percentage can be an indicator of health.
Over time, muscle mass naturally declines, and this reduction, called sarcopenia, can make everyday activities such as walking or climbing the stairs more difficult.
The percentage of muscle mass varies between people. It depends on several factors, including fitness, body size, and gender.
There are currently no specific guidelines for what a healthy or normal muscle mass percentage should be. However, a healthy body fat percentage can be a useful indicator of overall body composition.
The flaws of BMI
BMI is a calculation of a person’s body fat based on their height and weight. However, studies suggest it is a poor indicator of a person’s body fat percentage.
It can be misleading because the measure does not account for overall body composition or capture information on the mass of fat in different body sites. The latter relates to both health and social issues.
BMI cutoff points were generated mostly from the white population, but body fat distribution differs by race and ethnicity.
For additional information, talk with your doctor about other body fat assessment methods.
According to the American College of Sports Medicine (ACSM), guidelines for healthy body fat percentages in males are:
| Age (years) | 20–29 | 30–39 | 40–49 | 50–59 | 60–69 | 70–79 |
| Very lean | 4.2–6.4 | 12.5–14.9 | 9.5–13.0 | 11.1–14.9 | 12.0–16.1 | 13.6–15.5 |
| Excellent | 7.9–10.5 | 12.5–14.9 | 15.0–17.5 | 17.0–19.4 | 18.1–20.2 | 17.5–20.2 |
| Good | 11.5–14.8 | 15.9–18.4 | 18.5–20.8 | 20.2–22.3 | 21.0–23.0 | 21.1–22.9 |
| Fair | 15.8–18.6 | 19.2–21.6 | 21.4–23.5 | 23.0–24.9 | 23.6–25.6 | 23.6–25.2 |
| Poor | 19.8–23.3 | 22.4–25.1 | 24.2–26.6 | 25.6–28.1 | 26.4–28.8 | 25.7–28.0 |
| Very poor | 25.1–33.7 | 26.4–34.4 | 27.7–35.2 | 29.2–36.4 | 29.8– 37.2 | 29.3–37.3 |
ACSM guidelines for healthy body fat percentages in females are:
| Age (years) | 20–29 | 30–39 | 40–49 | 50–59 | 60–69 | 70–79 |
| Very lean | 11.4–14.1 | 11.0–13.8 | 11.7–15.2 | 13.8–16.9 | 13.8–17.7 | 13.7–16.4 |
| Excellent | 15.2–16.1 | 15.5–16.5 | 16.8–18.2 | 19.1–20.8 | 20.1–22.0 | 18.8–21.2 |
| Good | 16.8–20.0 | 17.5–21.0 | 19.5–23.6 | 22.3–26.6 | 23.2–27.5 | 22.6–26.3 |
| Fair | 20.7–23.5 | 22.0–24.8 | 24.6–27.4 | 27.4–30.0 | 28.3–30.8 | 27.1–30.0 |
| Poor | 24.4–28.6 | 25.8–29.6 | 28.3–31.9 | 30.7–33.8 | 31.5–34.4 | 30.9–33.6 |
| Very poor | 30.9–38.4 | 31.4–39.0 | 33.4–39.0 | 34.9–39.8 | 35.4–40.3 | 35.0–40.0 |
Maintaining a healthy muscle mass will help older adults counter sarcopenia and stay mobile.
It can also help with maintaining a healthy weight, as a higher percentage of muscle mass means a lower percentage of body fat.
In addition, there are various overall benefits to keeping the muscles strong and healthy, such as reducing the risk of injury. Also, forms of exercise that build muscle can also increase bone density.
Exercise that increases muscle mass may also have mental health benefits. For example,
Resistance training, or strength training, can increase muscle mass. It involves pushing or pulling to counter resistance from the body’s own weight, a resistance band, or another exercise tool.
Countering resistance places strain on the muscles, forming tiny tears in the muscles’ fibers. The body then heals these tears and adapts to strengthen the muscles.
With repetition, this process leads to an increase in muscle mass. It is usually necessary to gradually increase the amount of resistance over time in order to keep the muscles adapting.
It is important to take precautions to avoid injuries during these workouts, especially for older adults.
It may help to follow a certain diet, such as one that involves a high protein intake.
Learn more about building muscle mass through exercise.
Muscle mass refers to the body’s muscle tissue collectively. Often, people use the term to refer to the skeletal muscle only.
Calculating the percentage of muscle mass can help a person monitor or maintain their health, and maintaining muscle mass becomes more important as adults get older.
While it is difficult to calculate muscle mass precisely without specialist equipment, a person can start to estimate the figure by calculating their body fat percentage and then subtracting the number from 100.
