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  • Renpho ES-CS20M Smart Bluetooth Body Fat Scale

  • How We Tested

  • What You Should Know About Using a Smart Scale

  • Other Smart Scales We Tested

  • More Articles You Might Enjoy

A woman standing on the Renpho smart scale
Credit: Reviewed / Betsey Goldwasser

The Renpho smart scale packs all the features you'd want into a bathroom scale for an affordable price.

Best Overall
Renpho ES-CS20M Smart Bluetooth Body Fat Scale

The Renpho delivered consistent weight and body composition measurements throughout my week of weigh-ins, is a cinch to use, and the least expensive of the smart scales we tested, all of which make it our hands-down recommendation for top smart scale.

It works quickly—all other smart scales required more idle standing to register their body composition numbers than Renpho did. Partly, this is because Renpho only shows your weight on the display—it doesn’t scroll through the “smart” readings like others do. Instead, you must open the app to view those numbers—which, as a personal trainer, I think is a better idea. It means the Renpho can be used as a basic scale for daily use with ease, while providing that next-level data if and when it’s desired (see “What You Should Know About Using a Bathroom Scale,” below). What’s more, this was one of only scales that never gave me a funky first weight reading when I stood on it—a common calibration problem that can make you doubt a scale’s accuracy.

The moment I opened the app on my Android phone, the Renpho connected via Bluetooth to upload its stored data (at least a few days’ worth are saved in scale’s memory), even “knowing” enough to differentiate users in the app based on the readings it collects—the app asked if I was a different user when I performed tests holding dumbbells to make myself heavier. The data it records includes the usual fat and lean mass percentages, as well as an estimate of basal metabolic rate (i.e., the minimum calories your body needs to function at rest) and the percentages of subcutaneous (beneath skin) fat versus visceral (around the organs) fat. There’s no way of knowing if those metrics are accurate (and most likely they aren’t—see our “How We Tested” section). Still, the body fat readings I got were consistent from day to day over the course of my testing, meaning you can rely on the Renpho for tracking how a body may change over time.

My only real complaint about this scale is its size: Its platform was the smallest of any scale we tested. This felt noticeable to me—a small-framed woman who wears a size 7.5 shoes—especially in contrast to the rest. That said, I asked an over-6-foot-tall, size 12-footed friend to try it and he didn’t feel too crowded. The Renpho also maxes out at 396 pounds, on the lower side of the spectrum, which goes up to 440 for some scales. It’s also not the prettiest piece of bathroom decor, and if you get it in black, the surface will show dust and dirt without regular cleaning (a damp microfiber cloth does the job quickly, though).

All told, if you want a smart scale (or a basic one), the Renpho does it all and quite well—and is an exceptional value for its price.


  • Shows measurements quickly and accurately

  • Delivers data to Bluetooth app quickly


  • Small platform can feel awkward beneath the feet

  • Maxes out at 396 pounds

How We Tested

The Tester

I'm Amy Roberts, a managing editor here at Reviewed, where I oversee our health and fitness coverage. As a personal trainer, I’ve coached many clients toward achieving their fitness goals, including the desire to lose weight. A good smart scale that reliably measures the body’s mass (in pounds or kilograms), and provides percentages of body fat versus lean mass can be a valuable tool for tracking progress.

The Tests

For health purposes, having absolute accuracy in measuring your weight or body composition isn’t all that important. What is: the precision of a scale in taking those measurements day to day and week to week. If even one reading is way off, it casts doubt on the reliability of the scale as a tool and negates the log of your progress.

Replicability Tests

A friend of mine who was losing weight once mentioned to me that when he weighed himself every day, he’d hop on and off the scale several times and record the lowest number he saw. My goal in this review was to find scales that didn’t require that level of dedication (or precious time). So I did that for you: Every morning for a week, I weighed myself on each scale at least twice—more, if the two numbers didn’t match—and recorded the values for weight and body fat percentage.

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What I learned: If you must move the scale before recording your weight, you should tap the surface and see a “zero” in order to calibrate it first. (Yes, the instructions on all scales recommend this method, but who reads the instructions?)

Accuracy Tests

A hand weight placed on a bathroom scale
Credit: Reviewed / Betsey Goldwasser

Not all scales are accurate—but what's more important is that they are consistent.

As absolute accuracy isn’t important, we didn’t compare weights measured on these scales to ones of a calibrated scientific scale. Still, I wanted to see if there was some semblance of accuracy in the weights these scales recorded, both as raw data and to simulate how it would record the weights of different-sized people. Therefore, I took weights on each scale for:

  • a 25-pound dumbbell
  • a 50-pound dumbbell
  • me + a 5-pound dumbbell
  • me + 50 pounds of dumbbells
  • me + 100 pounds of dumbbells

The findings: None of the smart scales were dead-on for all of these readings, but none were so far off as to be statically problematic, let alone a problem for you.

Usability tests

Ultimately, the factors that set these scales apart are in their user-friendliness. For this, I considered:

  • The frequency of errors in measuring weight
  • How easy to read the numbers were
  • How comfortably my feet fit on the platform (I also “borrowed” the larger feet of an over-6-foot-tall friend)
  • How easy it was to clean (or, really, how little dirt or dust it showed) and store when not in use (spoiler: very little difference)
  • The variety of measurement units (pounds, kilograms, and even stones) and max weight capacity (typically equivalent to 400 pounds; some go up to 440 pounds)
  • The usability of the smartphone app (if applicable)
  • The perceived quality of the scale’s materials
  • The overall experience of using the scale

What You Should Know About Using a Smart Scale

Weight on its own isn’t the most useful measure of your body size, as it only tells part of the story—it provides a value for the sum total of you and doesn’t differentiate how much of you is fat or muscle or other lean mass (bone, skin, organs). That’s where a “smart” scale can be useful. These use bioelectrical impedance, which passes a low-level charge of electricity through your tissues, using the speed at which the charge returns to the device as the means to determine how much of each type of tissue it passed through.

Some smart scales differentiate body composition types to account for your relative bone mass, muscle mass, and body water content, while some only give “fat” mass and "lean" mass, which encompasses the other three. But this, too, is rife with its own accuracy and validity problems. In a stand-on scale, the charge only passes through the lower body (meaning if you carry more fat below the waist, you’ll come back with a higher body-fat percentage than is likely true). Secondly, your hydration level can alter the results.

All of that said, there’s value in taking recordings of weight and body composition—at the same time of day, to better control for your food intake and hydration variables—if you’re looking to track progress while following an exercise-and-nutrition plan. Smart scales all have companion apps that save your numbers electronically, so you don’t need to keep a pen and pad handy. If your goal is to lose (or gain) a significant amount of weight, hopping on the scale on a daily or weekly basis can show if you’re going in the direction you want, and at what rate. And by recording biweekly, monthly, or even bi-monthly body composition percentages, you may see a shift in the percent of muscle versus fat. Those numbers are especially useful to gauge the efficacy of a strength- or muscle-building plan and may help account for a weight plateau. When someone’s aim is to “tone up” (rather than lose or gain), they may not see a dramatic change in their total weight yet be building muscle while losing fat. A log of readings from a bioelectrical impedance device could capture that trend.

Other Smart Scales We Tested

Product image of Fitbit Aria 2
Fitbit Aria 2

If you’re a Fitbit superfan, you might consider the Aria 2 smart scale, which gave me reliable results from my weigh-ins. It’s a lot pricier than our top-pick Renpho, but if you value seamless integration into your Fitbit app, this is the only way to go. (You can also manually log your weight into the app, but where’s the fun in that?) The Aria 2 measures all of the same metrics as the Renpho; however, it takes a lot longer of you standing there to record its readings (a matter of seconds, really, but annoying in comparison) and even longer to sync them to the app. The latter may have been due to a slow WiFi connection, but with the scale mere feet from my router, I’m dubious.


  • Shows reliable numbers


  • Takes a long time to deliver readings and even longer to show them on the app

Product image of Garmin Index S2
Garmin Index S2

If you’re a faithful Garmin GPS watch wearer, I can see the allure of buying the company’s Index 2 Smart Scale, which sends weight and body composition data to the same Connect app, for an even more holistic picture of your fitness. The scale works statistically fine, in terms of recording readings that varied by no more than 1%. However, in my testing, I found it annoying to hop on and off the scale a couple of times in a row to have different weights and body fat percentages recorded, especially as the scale automatically displays a line graph showing up or down progress.

I tested the Index S2 separately from the rest of the field, more than a year later, so I can’t compare its numbers directly to the rest—when I first tested, I was training for a triathlon and was most certainly leaner. Still, it recorded my body fat percentage being a lot higher than I believe it to be in real life—disconcerting, to say the least. Unless you’re deeply entrenched in the Garmin ecosystem, and given the slight reliability issues, I can’t justify recommending you spend this much cash—approximately five times more than our top pick.


  • Large, easy-to-read display

  • Roomy platform


  • Small inconsistencies in measurements affect tracking log

Product image of Weight Watchers by Conair WW910 Body Analysis Bluetooth Scale
Weight Watchers by Conair WW910 Body Analysis Bluetooth Scale

I wasn’t a huge fan of the “smart” Weight Watchers by Conair Body Analysis Bluetooth Digital Bathroom Scale from the get-go: It made an unsettling creaking noise every time I stepped up on it. I wasn’t impressed with its performance, either. Despite being the only smart scale that required me to tap the surface first to calibrate to zero before stepping on, I got two inaccurate readings during my tests.


  • None that we could find


  • Inconsistent readings

  • Sounds like it's going to break when stepped on

Product image of Withings Body+
Withings Body+

The “smart” Withings Body+ looks sleek, but it failed to wow me with either its usability or its reliability. For starters, the scale’s feet slid around on my bathroom tile, so I had to be extra-careful when I stepped up. The display is crowded and it only scrolls the data once, and too quickly. You can take your time looking it over on the app—which, by the way, isn’t called “Withings,” which made it hard to find on my phone (it’s called HealthMate, fyi). The most disconcerting issue were the three bad readings I got over one week’s time. This isn’t a huge deal, except the app creates a line chart to show your weight trend, and mine was therefore all over the place. You can delete any erroneous weights manually—if you’re confident they’re actually wrong—but it would be better if they just didn’t happen in the first place.


  • Sleek, attractive aesthetic


  • Feet can slide on smooth surfaces

  • Partner app is difficult to use

Product image of Greater Goods Designer Bluetooth + BC Smart Scale
Greater Goods Designer Bluetooth + BC Smart Scale

I tested two smart scales from Greater Goods, this one and the Weight Gurus Bluetooth Body Composition Scale. On the plus side, the app setup is a friendly experience. On the minus side: inaccurate and wildly unreliable weight recordings. Without tapping the surface first to calibrate to zero, I weighed 23 pounds too light on multiple occasions.


  • Easy app setup


  • Often gave inaccurate and wildly unreliable weight recordings

Meet the tester

Amy Roberts

Amy Roberts

Managing Editor, Lifestyle


At Reviewed, Amy edits and writes articles on health, beauty, fitness, fashion, sleep, pets, and more.

See all of Amy Roberts's reviews

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