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Body-composition figures from any of these scales are wellness estimates, not clinical measurements. Nothing here is medical advice, and a health decision belongs with a qualified professional.
Updated August 2026: each maker’s published accuracy wording re-checked against its current product page, the peer-reviewed BIA error figures re-verified, and the three-year cost of Withings+ recalculated at Withings’ current subscription rates for the Withings Body Smart, eufy Smart Scale P3, and Renpho Elis Nova.
Three scales, one tier, and one accuracy question running through all three. The Withings Body Smart is $129.95, the eufy Smart Scale P3 is $89.99, and the Renpho Elis Nova is $72.99. All three advertise precision of 50 g, or 0.1 lb.
I’ve stepped on more bathroom scales than I can count over the years, in humid coastal bathrooms where the glass fogs before the number settles. The weight reading has never wobbled on me the way a body-fat percentage does.
That figure describes the load cells under the glass. It has nothing to do with the body-fat percentage, and none of the three publishes a margin of error for that number anywhere I could find. Renpho takes the tally at 70.0. Withings finishes last at 42.5, which will surprise anyone who has used its app, and I explain below exactly which weight is doing that.
“Precision up to 0.1 lb” is where smart scale accuracy stops
Every claim below is quoted from the maker’s own page. The middle column is what the claim actually covers once you read it against the hardware.
| The claim, as printed | What it covers | Verdict |
|---|---|---|
| Withings, Body Smart: “50 g (0.1lb) precision” | The weighing sensor. Withings prints no plus-or-minus figure for body fat on that page. | True, and about a different measurement than the one people buy it for |
| Withings, Body Smart: “clinically validated technology and 10+ years of data expertise” | No study is named on the page. The nearest thing Withings publishes is an in-house comparison of 80 people against DEXA, on a support article, with no journal, authors or DOI. | Unverifiable as printed |
| Withings, Body Scan page: the device “does not merely provide an estimate” | Withings’ own Body Smart article says a BIA scale “can estimate the body composition.” | Two Withings pages, two different claims about what the technology is |
| eufy, Smart Scale P3: “guaranteeing precision up to 0.1 lb / 50 g” | The weighing sensor. eufy publishes neither an electrode count nor a BIA frequency for either of its scales. | Strongest verb of the three, thinnest disclosure behind it |
| Renpho, Elis Nova: “ITO technology for accurate measurements” | An adjective. The quantified figure on the same page, 0.05 kg, is again the weight readout. | Vague, but it does not overclaim |
| Renpho, MorphoScan line: “Zero Subscription Fees” | Exactly what it says. Renpho’s app carries no paid tier that I could find on its US store or its App Store listing. | The only fully checkable claim in this table |
Which Brand Discloses How Its Scale Is Built?
Renpho is also the only one of the three that tells you how its scale is built. The Elis Nova page states four BIA electrodes. Withings describes a current in “the lower half of the body” and gives no electrode count or frequency for the Body Smart. eufy gives neither for the P3.
That matters more than it sounds. At this price tier all three are foot-to-foot devices, which means the current travels up one leg and down the other and the software infers the rest of you. Eight-electrode hand-to-foot hardware exists at each brand’s flagship tier, and we cover that tier separately in the body-scan comparison.
“Clinically validated” against what the FDA has cleared
Withings does hold FDA clearances. Seven of them show up in the 510(k) database, and none is for body composition.

The one people cite is K230812, cleared 23 August 2023 for the Withings Scan Monitor 2.0. Its Indications for Use describe recording and transferring a two-channel electrocardiogram and detecting atrial fibrillation. Body fat, bioelectrical impedance, muscle mass and visceral fat appear nowhere in it. A cleared ECG on the same sheet of glass confers nothing on the body-fat estimate sitting beside it.
Renpho has zero 510(k) records. Anker, which owns eufy, has two, both for wearable breast pumps.
So all three sit under the FDA’s General Wellness: Policy for Low Risk Devices guidance, docket FDA-2014-N-1039, reissued in January 2026. Products that are intended only for general wellness use and present low risk are, in the guidance’s terms, not regulated as devices at all. Claims about maintaining a healthy weight are named in it as an example. That is the regime these scales operate in, and it is the correct one. It just is not the same thing as clearance.
“Comparable to the Reference Method”? The Peer-Reviewed Numbers
Withings’ Body Scan support page reports correlations against DEXA of r = 0.99 for fat mass and r = 0.98 for lean mass, and concludes that the result is “comparable to that obtained by the reference method.” No margin of error is given, and no limits of agreement.
Correlation and agreement are not the same statistic, and the gap between them is the whole story here. A 2025 study of 1,000 active-duty US Marines using an InBody 770 — clinical-grade, eight-electrode, better hardware than anything in this comparison — reported a correlation of r = 0.89 for body fat in men alongside limits of agreement running from −10.01 to +1.57 percentage points. High correlation, and an agreement window nearly twelve points wide.
Two published numbers are worth carrying into a purchase decision.
| Source | What was tested | Reported error |
|---|---|---|
| British Journal of Nutrition, 2023 (Siedler et al., DOI 10.1017/S0007114522003749) | 15 BIA devices, 73 adults, against a four-compartment reference model | Precision error 0.0–0.49%. Cross-sectional constant error −3.5% to +11.7%; standard error of the estimate 3.1–7.5% |
| JMIR mHealth and uHealth, 2021 (Frija-Masson et al.) | Three consumer smart scales including a Withings Body Cardio, against DEXA, in a hospital physiology unit | Median weight error 0 to 0.3 kg. Median fat-mass error −2.2 to −4.4 kg; the Withings unit −3.7 kg |
What Do the Published Error Rates Show?
Read those two rows together and the picture is consistent. These devices are extremely repeatable and not very accurate. Precision error under half a percent means the scale will tell you the same thing tomorrow. A standard error of the estimate up to 7.5 percent means the thing it tells you both days may be several points off the truth.
The British Journal of Nutrition authors found tracking change over time considerably better than measuring the absolute number, with constant error narrowing to −0.4% to +1.3% over a 12-to-16-week follow-up. The JMIR authors were blunter: “Smart scales are not accurate for body composition and should not replace DEXA in patient care.”
What Does the CDC Say About Body-Composition Scales?
One more piece of context, from the government that measures this for a living. The CDC’s NHANES Body Composition Procedures Manual evaluates national body composition by anthropometry and DXA. Earlier survey cycles collected bioelectrical impedance. The current one does not.
Weigh yourself daily if the habit helps. Watch the body-fat line as a trend, not as a measurement, and none of that requires a $129.95 scale rather than a $72.99 one.
“1 Month Free” and What a Withings Scale Really Costs
Withings is the only one of these three with a subscription, and it is fairer than its reputation. Weight, body fat, water mass, bone mass, muscle mass and visceral fat all stay visible without paying. What Withings+ unlocks is the interpretation layer: the Health Improvement Score, the predictive insights, the programmes. On the newest hardware it also gates named metrics, including Heart Age and a Glucose Resilience Score.

Here is what three years costs, computed at each published rate.
| Scale and plan | Hardware | Subscription over 36 months | Three-year total |
|---|---|---|---|
| Renpho Elis Nova | $72.99 | None offered | $72.99 |
| eufy Smart Scale P3 | $89.99 | None offered | $89.99 |
| Withings Body Smart, no subscription | $129.95 | $0 | $129.95 |
| Withings Body Smart + Withings+ annual | $129.95 | 3 × $99.50 = $298.50 | $428.45 |
| Withings Body Smart + Withings+ monthly | $129.95 | 35 × $9.95 = $348.25, after one free month | $478.20 |
Prices are approximate, current as of publication, and change frequently — confirm the latest price with the retailer before buying.
Why Do Withings’ Own Pages Disagree on the Price?
A flag on that arithmetic, because Withings does not agree with itself. Its Body Smart product page and its “Subscribing to Withings+” support article both give the annual rate as $99.50. Its Withings+ FAQ and its terms and conditions both give $99.95. At the higher figure the three-year total is $429.80. The monthly rate is $9.95 on every page. The free trial is one month if you buy hardware from Withings and two weeks if you subscribe from inside the app, so the “1 month free” line does not apply to everyone who reads it.
There is a second hook worth knowing before you buy. Withings+ Protect is lifetime warranty coverage that exists only while the subscription is active. Its terms, dated 27 April 2026, require an “active, fully paid, and uninterrupted” membership and exclude complimentary access, so the free month does not count. Miss a payment and coverage is suspended with a grace period of up to one month; do not reactivate and the warranty is “permanently voided” for every Withings product it covered.
“No corresponding product found” — eufy’s own US store, on eufy scales
The direct product pages for the eufy Smart Scale P3 and P2 Pro are live and show stock. Its US collection pages for smart scales return no products at all, and one of them returns that sentence. The European store lists a different lineup again, with a C20 and a P2 Pro and no P3.
The warranty position is the same shape. eufy’s US warranty table itemises stick vacuums at 24 months, robot vacuums at 12, smart locks at 18, and has no row for smart scales at all. Its Australian warranty page lists smart scales at 24 months. The US P3 page offers a 30-day money-back guarantee and the phrase “Hassle-Free Warranty” with no period attached.
I could not establish a US warranty term for a eufy scale from any eufy source. That is not a complaint about customer service. It is a gap in what the company publishes, and it is the reason eufy scores a 2 on that axis below.
Scoring Smart Scale Accuracy and Disclosure
Five axes, each weight argued in a sentence. Published measurement detail takes 25 percent, because a buyer cannot compare hardware a maker declines to describe. Claim discipline takes 20 percent, meaning whether the advertised precision figure describes what a buyer thinks it describes. Cost after purchase takes 25 percent, because a subscription and a warranty tied to it are real money. Published warranty takes 15 percent. Price takes 15 percent.
Notice what is missing: app quality, ecosystem breadth and design. Withings wins all three of those and I did not score them, because they are preference and the four axes above are checkable. Weight app experience at 40 percent and Withings takes this comfortably. That is a legitimate reading and the numbers are here for you to redo.
| Axis (weight) | Withings Body Smart | Renpho Elis Nova | eufy Smart Scale P3 |
|---|---|---|---|
| Published measurement detail (25%) | 3 — no electrode count, no frequency | 6 — states four electrodes; no frequency | 2 — neither published |
| Claim discipline (20%) | 4 — “clinically validated” with no citable study; two pages disagree on whether BIA estimates | 5 — vague adjective, no overclaim | 4 — “guaranteeing” attached to a weight figure |
| Cost after purchase (25%) | 3 — auto-renewing subscription; warranty extension dies with it | 9 — states zero subscription fees | 8 — none found |
| Published warranty (15%) | 8 — 2 years, product page and FAQ agree | 6 — 18 months, website purchases only | 2 — no US term published |
| Price (15%) | 5 — $129.95 | 9 — $72.99 | 7 — $89.99 |
| Tally | 42.5 | 70.0 | 46.5 |
How Do the Scores Add Up?
The arithmetic. Renpho: (6 × 0.25) + (5 × 0.20) + (9 × 0.25) + (6 × 0.15) + (9 × 0.15) = 1.50 + 1.00 + 2.25 + 0.90 + 1.35 = 7.00, or 70.0 out of 100. eufy: 0.50 + 0.80 + 2.00 + 0.30 + 1.05 = 4.65, or 46.5. Withings: 0.75 + 0.80 + 0.75 + 1.20 + 0.75 = 4.25, or 42.5.
One ratio, since the warranty numbers are unequal. The Withings costs $5.41 for each of its 24 warranted months, $129.95 divided by 24. Renpho costs $4.06 for each of its 18, $72.99 divided by 18. The eufy cell stays empty, because there is no published US term to divide by.
“Hassle-Free Warranty” and two other things you buy at this tier
Renpho Elis Nova: Smart Scale Accuracy, Cheapest Tier
Wins on the two axes that cost a company nothing to satisfy and that the other two did not: it says how many electrodes it has, and it says there is no subscription. Eighteen months of warranty, and the full eighteen only if you buy from Renpho’s own site.
Skip this if you already live inside Apple Health or a Withings ecosystem and want one app for a watch, a monitor and a scale. Renpho does not compete there.
eufy Smart Scale P3: Accuracy Claims vs. Disclosure
The middle option on price, the last on disclosure. No subscription, which is worth real money over three years, and an independent reviewer at Wareable confirms the app carries no paid tier. Against that: no electrode count, no frequency, no US warranty term, and a US store whose own collection pages say it has no scales.
Skip this if you would want a warranty claim to go smoothly. Buy it only after confirming the current US warranty period in writing.
Withings Body Smart: Where Its Smart Scale Accuracy Falls Short
The named loser on this ledger, and it is a loss on paperwork rather than on hardware. The app is the best of the three and the two-year warranty is the longest anyone here publishes plainly. It finishes last because it says the least about how the scale measures, says the most about validation without pointing at a study, and is the only one that can turn a $129.95 purchase into $428.45.
Skip this if the body-fat number is the reason you are buying. The extra $57 over the Renpho buys a better app, not a better estimate.
“Zero Subscription Fees” and the Smart Scale Accuracy Verdict
The Renpho is what I would spend my own $73 on. Not because it measures body fat better, since there is no published evidence that it does or that any of them do well. Because it is the cheapest way to get a scale that weighs to 0.1 lb, tells you how it is built, and cannot bill you again. If you want the ecosystem, buy the Withings and skip the subscription; the metrics you actually read stay free.
More in our Health & Fitness section, including which scale data to trust during a weight-loss push and how foam rollers, massage balls and percussion guns compare.
If eufy publishes a US warranty period for its scales after this goes up, send it over and I will add it. The contact page works.
































