The Best Body Composition Tool Is Free
Most of us don’t really want to simply “lose weight.” Instead, your goal is to lose fat while preserving bone, muscle, and other lean tissues. Likewise, if you’re aiming to gain weight, you’re probably looking to add more muscle—not just any kind of weight. This is why the humble scale can sometimes be misleading—a person losing fat might see little change on the scale if they’re also building muscle.
Measuring body composition gives a clearer picture than weight alone. While the gold-standard methods like underwater weighing, Bod Pod, and DEXA scans provide accurate readings, they’re often expensive and not readily available for everyday use.
For the average person, there are three practical options:
Taking measurements: Nearly free and incredibly accessible.
Using body fat calipers: Affordable, though they require proper training.
Investing in a body fat scale (BIA): Convenient but can be costly and less precise.
Among these, the good old-fashioned tape measure stands out for its simplicity and affordability. By measuring key body parts, you can even plug these numbers into an equation to estimate your body fat percentage. But how accurate is this method?
How the Study Worked
Researchers teamed up with the Walter Reed Military Medical Center to test the reliability of tape measures compared to more advanced devices. They recruited 62 military members—25 men and 37 women—who underwent several body composition assessments:
DEXA scans: Using X-rays to estimate body fat with an accuracy of within 1–2%, these served as the control method.
Body circumference measurements: A tape measure was used to record the circumference of the neck, waist, and hips. Each measurement was taken three times and then averaged.
Bioelectrical Impedance Analysis (BIA): Two commercial models (DSM-BIA 500 and DSM-BIA 1000) were used. These devices send a small electrical current through the body and estimate body fat based on how quickly the current moves through different tissues. Note that these models are designed for professional use and cost significantly more than consumer versions.
The study did not evaluate calipers or less expensive BIA scales available on the market.
What the Study Found
Both the tape measure and the BIA models slightly underestimated body fat compared to DEXA. Interestingly, the underestimation was more pronounced in males than females, but all methods were within 1.4 to 5.5 percent of the DEXA results.
Takeaways
For many of you, a tape measure is more than sufficient. While it might not give you a perfectly accurate body fat percentage, it’s an inexpensive and straightforward way to track whether you’re moving in the right direction.
Wondering how to convert those measurements into a body fat percentage? Here’s a FREE Body Fat Calculator does the math for you. Here’s what you need to do:
Measure the widest part of your neck.
Measure the narrowest part of your waist (this might be at or just above your navel).
Measure the widest part of your hips.
Make sure the tape is snug but not too tight. If you ever need more precise tracking—especially if you’re an athlete or your performance hinges on these numbers—consider discussing advanced methods like DEXA scans or Bod Pod measurements with your coach.
Remember, your body fat percentage is just one indicator of your overall health. It’s not a measure of your worth. Use it as one of many data points to guide your progress.
Closing Thoughts
Over the years, I’ve personally tested numerous methods to track body composition—from using a simple $7 skin caliper to experimenting with advanced bioelectrical impedance machines and even some rather outlandish tools. I’ve seen it all: the infrared monitoring device that required a strange “jelly” application, DEXA scans that set you back $50 a pop, and even a Bod Pod in a gym parking lot. What I’ve learned is that while no method is perfect (only cutting you open would provide 100% accuracy!), the real value lies in tracking trends over time.
Pick a method that works for you and stick with it. Consistent data beats chasing absolute precision every time. Trust the trends, and let them guide you on your journey to better health.
Take care of yourself, no one else can do it for you.
– Michael Beiter
Personal Trainer
Nutrition, Sleep, Stress management, and Recovery coach