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The Digital Scale for Body Fat and Muscle Mass Calculator

THE BEST Body Fat Scale!

We’ve used this scale for years. Our personal trainers used it and introduced us to it as well as our naturopathic doctor trained in exercise science. If you’re serious about health and fitness with fat loss and muscle gain, this is definitely for you!

If you’re reading this, chances are you already know that your body fat percentage is critical to achieving your overall fitness goals. Chances are that you also know that physique is not the only place that more muscle and less fat make a difference.

More muscle and less fat reveals a lower biometric age.

With a Tanita body fat calculator, you can also track your biometric age. We love how you can see a direct association between fat loss and lowered biometric age, and muscle gain to improve your fitness age. Muscle gain and fat loss improves your fitness age.


Fitness is About More Muscle, Less Fat.

But how do you track it? Do you weigh every day, once a week, or randomly? Some say it’s best to do it daily, others weekly. Some (and I’ve been there 😯) avoid weighing because they don’t want to know the bad news. But not knowing doesn’t change anything. In fact, it typically makes it worse.

Too many people who want to lose weight, just eat less, and often lots less, to drop pounds. I did that for years. The problem with that is that losing weight that way means losing fat, but also losing too much muscle.

The more muscle you lose, the weaker you become, the less fit and the slower your metabolism, because muscle burns more calories than fat. That’s why when you do a muscle building workout versus a straight cardio, you continue burning calories even after you’ve left the gym.

Fitness isn’t Your Number on a Weight Scale

We are all so conditioned to think of fitness as measurable by weight. However, weight is just a number on the scale, unless you have a way to also track fat loss and muscle gain. As you build muscle, you may actually gain weight in terms of that number on the scale.

But don’t despair and drop those weights now, because it’s not about where the needle lands on the scale. Rather, it’s about the story behind the needle. It’s about body composition, and the simplest way to ascertain your body composition is with a body scan monitor.

In fact, some bodybuilders with very low body fat can actually show up in the overweight or even obese category if you’re only judging by scale weight or Body Mass Index. BMI is well known to be a very poor and outdated assessment of actual body fat, and yet many still use it because it’s what people know. It’s time for a new metrics on obesity, body health and physique rating, and Tanita is the best system for that.

Muscle is more compact than fat, so you can actually gain weight while losing inches.

Essential Equipment: a Body Composition Scale

Measuring body fat to muscle is essential for weight loss. Weight loss without muscle gain, will not create the fit physique you want, and without increasing muscle percentage it will be harder to keep off the weightloss.

This is why we love the Tanita Body Composition Scale (pictured below). For years now, we’ve used the awesome Tanita BC-558 Ironman Segmental Body Composition Monitor, and love it!! (There is a less expensive model that we now own that we’ll get to in a minute).

Tanita BC-558 Ironman Segmental Body Composition Monitor

Without this tool, your fitness journey could be somewhat of a guessing game. This is the perfect scale for serious bodybuilders as well as anyone eager to lose fat, gain muscle, and get healthier and fitter.

Next, we cover charts and more on why Tanita is a great tool for bodybuilders.

The reason it’s the perfect tool for bodybuilders, is because it measures the fat and muscle composition of each area of your body: each arm, each leg, torso and entire body.

Our Bodybuilder Friend Loves It!

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We recently gave our Tanita BC-558 to a heavy weight bodybuilding friend, Randy Ganther. He was visiting for a couple days, tried it and loved it. He’s in awesome shape as a powerlifter because he’s very disciplined, methodical and consistent in his training and food regimen. For him bodybuilding is a no-compromise, fixed asset in his schedule, even when he’s traveling.

He knows his approximate body metrics such as fat and muscle percentage. However, what he did not know, that the Tanita BC-558 revealed to him, is that one of his arms and legs were comprised of a pound or two more muscle than the other.

The Tanita scale sees your body metrics even before your mirror does.

For a bodybuilder lifting heavy, this kind of variance could create bigger imbalance problems down the road, such as skeletal distortions and undue muscle and ligament strain in other areas, yet it could be something that wouldn’t show up for awhile, until there was an ache or pain or injury.

Having this Tanita BC-558 allows him to see—even daily if he wanted, though he typically weighs weekly—the immediate results of his training.

When I weigh daily, I can see the direct results of my activities (or lack of) on the scale. I see the good news: how muscle can increase in one day after one workout and subsequently reduce my metabolic age and fat percentage. And the bad news: how one day no exercise can reduce the muscle mass and show a gain in fat percentage, even if by a few decimal points.

It’s a fat loss, muscle gain, training tool for anyone serious about losing fat and building muscle.

The BC-558 that we gave to our friend, costs $350 new. We gave it to him because we got a new one with a Bluetooth activated app that allows us to track our progress on our iPhones. It works amazingly well, and in terms of basal metabolic rate, it seems to work even better than the BC-558.

What the Tanita BC-558 Ironman Segmental Body Composition Monitor does:

Tanita BC-558 Ironman Segmental Body Composition Monitor

Features and Specifications:
Tanita BC-558 Ironman Segmental Body Composition Monitor, $372.99 on Amazon
  • Weight
  • Full body fat %
  • Segmental body fat% (including right arm, left arm, right leg, left leg, and trunk)
  • Total body water%
  • Full muscle mass
  • Segmental muscle mass (including right arm, left arm, right leg, left leg, and trunk)
  • Physique rating
  • Basal metabolic rate
  • Metabolic age
  • Bone mass
  • Visceral fat
  • Automatic scrolling or results: weight, body fat% and segmental body fat %
  • Recall function: weight, body fat %, body water %, muscle mass, BMR, bone mass and visceral fat
  • Graph function for: body fat % (total and segmental), body water %, bone mass, visceral fat and BMR
  • Graph recall: calendar days / 52 weeks / 36 months
  • Clock & calendar
  • Backlit icon buttons
  • Guest mode
  • Weight only button

Our new Tanita RD-901 BK Ironman iPhone Scale

The Tanita RD-901 BK Ironman iPhone Scale, synchronizes via bluetooth from iPhone to the scale via a free app that’s very easy to set up; the app walks you through the steps, so you can set up your personal profile. My husband set his up on his phone and I did mine on my phone, so it can serve multiple users.

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When you’re ready to weigh, just click on the free iPhone app icon, select ‘Measurements’, then ‘Take New’. The Tanita immediately starts communicating with your scale via Bluetooth. The scale turns on instantly, finds your profile, which it shows you by nickname you’ve designated (we used our initials), and it shows your age, so it’s double confirmed to be your profile. Then you hop on the scale and in seconds it has assessed and calculated your:

Features and Specifications:
Tanita RD-901 BK Ironman iPhone Scale
  • Weight
  • Body fat %
  • Body water %
  • Muscle mass
  • Physique rating
  • Basal Metabolic Rate
  • Metabolic age
  • Bone mass
  • Visceral fat
  • BMI
  • Weight only button
  • 4 users
  • Guest mode included
  • Includes gravity setting for greater accuracy

The RD-901 does not analyze limbs and torso (arms, legs and trunk) like the BC558.

“The addition of hand grips to Tanita’s standard platform-based electrode system allows the BC-418 body composition analyzer to calculate regional body composition, empowering healthcare professionals to better determine health risks associated with abdominal fat.” Tanita.com1)

The RD-901 is less expensive at around $200 as of this writing. So it just depends on if you need/want the extra deep dive into percentages per area of the body, or, if you want a fast read on your iPhone without specificity as to where the muscle and fat reside.

I do miss that specificity, because it’s really cool to track your muscle gain and fat loss by body area as it can really help you to hone in on the efficacy of your workouts and tweak them accordingly.

The Tanita is more than a scale; it’s a body scanner.

But I really like the super quick and simple RD-901 as it doesn’t require the paper tracking that you need to do with the BC-558. (See the forms below). And, since I’m into fitness for health, toning more than bodybuilding, it’s not as critical to hone in so specifically. Just fun to know, but not as essential.

The BC-558 can store three days of history, however, for the best tracking of your progress, you do need to fill out a form and manually enter the data, which takes a couple extra minutes.

The phone app is instantaneous.

With both models and tracking systems, you can see a history of your progress. One (BC558) is on paper in chart form, the other (RE-901) is on your phone in list and graph form.

I wish the 901-RD did track the specific body parts, however the efficiency and elegant simplicity of this version is not only superior, but I think it’s a tad more accurate. Perhaps just because it’s newer. For instance, my Metabolic Age is higher on the 901-RD app: I’m 58 and it shows a current metabolic age at between 35-45 compared to 28-32 on the BC558.

However, our BC558 was four years old when I gave it to Randy. Hopefully Tanita is regularly updating their technology for the most accurate readings. That is after all, their specialty.

Forms Used with the Tanita BC558


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Tanita Charts PDFs

So… how does this work?

How Losing Weight Can Make You Fatter

Info from Tanita’s site and brochure:
“A” and “B” were the same height and weight, and had the same percentage of body fat. Each lost 10 lb. over the same period of time. Although their weights are identical, “A” is now fatter. She simply cut calories, resulting in loss of muscle tissue, meaning her percentage of body fat increased. By exercising and eating right, “B” lost 10 lb., and her body fat dropped to 21%.2)


It’s Important to Know Your Body Fat

It’s not the amount of weight you have but the amount of body fat that’s potentially dangerous to your health. Carrying too much body fat can increase your risk of developing serious health problems such as high blood pressure, high cholesterol, heart disease, diabetes and cancer.

Your body fat number is more important than your weight number.

Maintaining a healthy body fat percentage can reduce your risk and help prevent the onset of these conditions. Until now, getting a body fat reading has been expensive and time-consuming, usually conducted only through medical and athletic facilities—or simply left to guesswork.

Tanita products give you a more complete picture of the shape you’re in because they tell if you’re losing pounds from fat or from muscle. They’re essential tools for monitoring the progress of any exercise and diet program. They provide the facts you need to make the right decisions, and used over time, they can help you take the right steps toward a healthier life.

How BIA Works

Tanita uses a state-of-the-art method of body composition assessment called Bioelectrical Impedance Analysis (BIA).

Not to be confused with BAI, which you can read more about here.

Body impedance is measured when a safe, low electrical signal (about 50kHz, 500 Micro Amp) is passed through the body, carried by water and fluids.

Fat tissue does not contain much water and creates resistance or impedance to the signal. (Fat is approximately 10-15% hydrated, whereas muscle is normally between 50-70%.) This impedance information is then used to calculate the amount of lean and fat tissue within the body.

Through a process called multiple regression analysis, Tanita has developed highly researched proprietary formulas that are based on impedance, height, weight, gender, body type (normal adult or athletic build), and in some cases, age.

Tanita’s reference is Dual Energy X-ray Absorptiometry (DEXA), which many experts now believe is better than Hydrostatic Weighing because of its accuracy and reliability. All analytical methods use equations derived from large, multi-ethnic population studies to predict body composition.

The integrated monitor-scales are cleared by the FDA, easy to use, provide clinically accurate results, and make body composition assessment accessible in professional environment as well as the home.

In Conclusion – Which Tanita Scale is Best for You?

So there you have an expanded perspective and comparison of two of the Tanita home scales. They have professional models. I first learned of it when standing on the commercial version used by my naturopathic doctor and first fitness mentor, Dr. Jade Teta. So here’s a summary of our top 3 body fats scales by use.

Best Professional Scale for Health Professionals

(If you’re not a health and fitness professional, scroll down to the next section).

If you’re a doctor or fitness professional coaching and training clients, you can add significant value to your clients by investing in the professional version of the Tanita scale. Complete with the ability to create printouts of client body metrics, such as the Tanita MC-780U is the top of the line best and most accurate body fat scale.

This professional body fat scale by Tanita MC-780U is the latest technology with the most accurate printable and trackable results in just 20 seconds for clients and patients up to 600 lbs.

Features of the Tanita MC-780U

  • User Friendly
  • Latest technology
  • FDA approved type 2 medical device
  • Record multiple measurements in 20 seconds:
  • Segmental fat
  • Muscle mass
  • Basal metabolic rate
  • Visceral fat levels
  • Weighing capacity of 600 lb (270 kg)
  • Auto calibration before each analysis
  • Bioelectrical Impedance Analysis (BIA) technology (safe, low-level electrical signal)
  • Clinically comparable to x-ray absorptiometry and hydrostatic (underwater) weighing
  • Extra-large LCD display console, reverses for clinician view
  • Printable full consultation sheet c
  • Assess fitness program effectiveness
    • Multiple Outputs
    • built-in SD card facility collects data
    • USB and RS-232 connectors for simple integration with EMR systems
    • database management
    • client IDs for collecting continuous measurement data
    • ideal for research studies
    • compatible with HealthWare Software allowing full database management
    • The MC-780U reports are compatible with the following printers:
      • Canon Pixma iP4820
      • Canon Pixma MP560
      • Epson Artisan 837
      • Epson XP-820, XP-830

Sample Tanita MC-780U Printouts:

weight scale & body fat calculator
Sample printout from Tanita’s professional body fat calculator, MC780U. Image by

Best Body Fat Calculator for Bodybuilders and Powerlifters

If you’re a bodybuilder, powerlifter, figure competitor, etc., consider the BC-558.


Best Body Fat and Weight Scale for Fitness Enthusiasts

If you’re into health and fitness and trying to keep close watch on your body metrics, fat content and muscle mass, and you have an iPhone, I think you’ll be satisfied with the RD-901.

There are other versions and tools by Tanita, but these listed are the ones we’re familiar with and should get you going in the right direction.

Oh! And…. here’s Randy, heading to the gym early a.m., even while on vacation! 💪🏼💪🏼

The Tanita body fat calculators may just be the most accurate bathroom scale you can buy, while helping you stay lean and healthy to boot!

Be Fit!

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Hello! I’m LeAura, a former homeschooling mom, fitness professional, entrepreneur, author, ideator, web publisher, and podcasterpassionate about helping others achieve their best possible life! I’m the owner of this site and a few others that I run along with my entrepreneurial family in areas that interest us, because we love to create and we love to share! If you really want to know more about me, you can check our ‘About’ page. (And while you’re there, please tell me about you)!

We haven’t created our family publishing company site yet, but as soon as we do we’ll link that here. Meanwhile, if you’re into gardening, you can see our gardening site, And, if you’re into creating anything, please visit our creators site,
Thanks for reading… take care and be fit!
LeAura Alderson, owner,

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