BMI Result: 5ft 8in, 121 lbs (BMI 18.4) - Male
According to CDC and WHO standards, a BMI of 18.4 is classified as Underweight.
A male who is 5ft 8in tall and weighs 121lbs has a BMI of 18.4, which falls into the Underweight category used by the CDC and WHO for adults.
| Category | BMI Range |
|---|---|
| Underweight | < 18.5 |
| Underweight | < 18.5 |
| Obese | ≥ 30 |
Healthy weight range for 5ft 8in: 122 lbs – 164 lbs
Metric: 172.7 cm, 54.9 kg
📏 Healthy waist circumference for your height: 35" – 40" (below 40" for male)
So you're 5ft 8in and weigh 121lbs. Your BMI is 18.4, which falls into the Underweight category according to CDC and WHO standards. Let's break down what this means for your health.
Adjust Your Numbers
Change your height or weight to see how your BMI changes.
Understanding Your BMI
A BMI below 18.5 may indicate nutritional insufficiency. According to the CDC, this range is associated with increased risk of bone density loss and immune function decline. Consulting a healthcare provider is recommended for a thorough nutritional assessment.
What This Means for Your Height
For men of average height, BMI is a reliable screening tool. The CDC recommends keeping waist circumference below 40 inches to minimize health risks.
Weight & Threshold
Gaining approximately 0.7 lbs would bring your BMI to 18.5, the start of the next category.
⬆️ Gaining approximately 0.7 lbs would put you in the Normal BMI range.
Waist & Health
The CDC recommends that men keep waist circumference below 40 inches. A waist-to-height ratio below 0.5 is also associated with lower health risks.
Age Context
For adults 65 and older, BMI targets shift. Clinical guidelines (ESPEN, NIH) often recommend a slightly higher BMI range (around 23–26) for seniors to protect against bone loss and muscle decline. At 67 years old, a man at 5ft 8in and 121lbs has a BMI of 18.4.
Your BMI of 18.4 is within the standard range but sits near the lower end. Maintaining muscle mass through protein intake and light resistance training is particularly important at this age.
👉 Use our Senior BMI Calculator for age-stratified recommendations.
👉 Check our Asian BMI Calculator for ethnicity-specific guidelines (if applicable).
Health Analysis
Recommendations
General Health
A BMI of 18.4 is below the CDC and WHO healthy range of 18.5-24.9. This may indicate nutritional insufficiency. Consulting a healthcare provider is recommended for a thorough nutritional assessment.
Monitoring
In addition to BMI, pay attention to waist circumference. The CDC recommends males stay under 40 inches. Regular tracking of your measurements over time provides the most useful insight into your health trends.
Next Steps
If you're concerned about your weight or body composition, a healthcare provider can offer personalized guidance based on your full health profile.
Personalized Notes
Physical Activity
For a man at 5ft 8in, focus on strength training 3-4 times per week to build muscle mass. Compound exercises like squats, deadlifts, and bench press are most effective. The CDC recommends consulting a healthcare provider before starting any new exercise program.
Diet & Nutrition
At 5ft 8in and 121lbs, a BMI of 18.4 indicates underweight. For men of this height, the CDC recommends a healthy weight range of 121-163lbs. Focus on protein-rich foods and resistance training to build muscle mass.
Frequently Asked Questions
How common is a BMI of 18.4 for a 5ft 8in man?
What else should I track besides BMI for a 5ft 8in man?
How do I calculate my BMI at 5ft 8in and 121lbs?
How does a BMI of 18.4 affect health for a 5ft 8in man?
Related Tools & Articles
💡 About this calculation: BMI = (121 × 703) ÷ (68 × 68) = 18.4 | Metric: 172.7 cm, 54.9 kg
📖 Recommended reading:
Editorial Review: This page was generated by the BMI Calculator Web Editorial Team and reviewed at template and content-pool level for accuracy and guideline alignment by Dr. Sarah K. Johnson, PhD, RD. All content is aligned with current WHO, CDC, and NIH guidelines.
Published: 2026-08-15