The Xiaomi Body Composition Scale S400 is Xiaomi’s smart bathroom scale that measures far more than weight. It sends two alternating currents, at 50 kHz and 250 kHz, through the body to estimate 25 body composition indicators, shows weight, body fat and heart rate on the scale itself, and syncs the full report to the Xiaomi Home app over Bluetooth. We sell it in white, and some shops list it as the Xiaomi Body Fat Scale S400; Xiaomi’s official name is Body Composition Scale S400, model MJTZC01YM.
Table of Contents
How the Body Composition Scale S400 Measures
Most basic smart scales pass one low-frequency current through the body and estimate fat from a single impedance reading. The Body Composition Scale S400 uses two: a low frequency of 50 kHz and a high frequency of 250 kHz. Xiaomi explains that the two frequencies pass through cell membranes differently, which lets the scale separate impedance inside and outside the cells instead of relying on one number.
Xiaomi benchmarked the S400 against DEXA, the dual-energy X-ray method used in clinics for body composition. Its published result is a correlation coefficient of 0.93 or higher for key data such as body fat percentage and fat mass; the footnote specifies the 0.93 figure for fat mass. That is a correlation with DEXA, not a medical diagnosis, and the scale is a wellness device rather than a medical one.
25 Body Metrics and What the Scale Shows
The full analysis covers 25 body composition indicators, viewed in the Xiaomi Home app (Mi Home). Xiaomi lists weight, body fat, heart rate and battery level as the readings shown directly on the scale’s display, so you see the essentials the moment you step off, and the complete report on your phone.
The Body Composition Scale S400 also measures static heart rate: beats per minute while you stand calm and still on the scale. It is a resting snapshot taken during the weigh-in, not continuous monitoring.
One Scale for the Whole Family
The S400 stores information for up to 36 family members, through a main account, five shared accounts and virtual users created in the app. It recognises each person automatically when their weight is within ±2 kg of their previous reading, so a household can share one scale without selecting profiles every morning.
Extra modes cover the moments a normal scale cannot: a baby holder mode for weighing infants and pets while you hold them, balance testing, a visitor mode for guests, and small object weighing from 0.1 kg to 10 kg, accurate to 0.1 kg (those small-object results under 10 kg are not saved). Body composition is measured for users aged 6 to 80; outside that range the Body Composition Scale S400 records weight only.
Battery, App and Build
Three AAA alkaline batteries power the scale. Xiaomi rates them at 180 days under its test conditions: three weigh-ins a day of about 45 seconds each, at 25°C. Heavier daily use by a large family will shorten that.
The Body Composition Scale S400 connects over Bluetooth Low Energy 5.0 and works only with the Mi Home/Xiaomi Home app; Xiaomi states it is not compatible with the Mi Fitness app or any other app. It needs Android 8.0 or iOS 12.0 and later. The platform is 300 × 300 × 24.55 mm in reinforced glass and engineering plastic, weighs 1.45 kg and measures from 0.1 kg to 150 kg in kg or lb.
Who This Is Not For
Anyone with an implanted medical device such as a pacemaker: Xiaomi does not recommend the scale for them, because it passes a small current through the body. Xiaomi also advises pregnant women to use it with caution.
People who track health in Mi Fitness, Apple Health or another platform and want the data there. Xiaomi says the S400 works only with Mi Home/Xiaomi Home.
Users above 150 kg, the scale’s maximum, and children under 6 or adults over 80 who want body composition rather than weight alone. And anyone expecting batteries in the box: Xiaomi lists only the scale and the user manual as package contents, so plan to buy three AAA cells.
Buy the Body Composition Scale S400 in the UAE
We sell the Xiaomi Body Composition Scale S400 in white with a 1-year warranty from Totot. It is delivered to every emirate within 3 business days, with free delivery on orders from AED 300. A defective or non-matching item can be returned within 14 days, and any shipping damage should be reported within 48 hours of delivery.
Technical Specifications
- Product name: Xiaomi Body Composition Scale S400
- Model: MJTZC01YM
- Colour: White
- Measurement method: Dual-frequency bioelectrical impedance, 50 kHz and 250 kHz
- Body metrics: 25 body composition indicators in the Xiaomi Home app; static heart rate
- DEXA benchmark: Correlation coefficient ≥ 0.93 for fat mass (Xiaomi’s published test)
- On-scale display: Weight, body fat percentage, heart rate, battery level
- Weighing range: 0.1 kg – 150 kg
- Units: kg, lb
- Minimum division: 0.1 kg
- Users: Up to 36 family members; automatic recognition within ±2 kg
- Modes: Baby holder (infants and pets), balance testing, visitor, small object weighing 0.1–10 kg
- Body composition age range: 6–80 years (weight only outside this range)
- Batteries: 3 × AAA alkaline, 4.5 V; up to 180 days (3 weigh-ins a day of about 45 s, at 25°C)
- Connectivity: Bluetooth Low Energy 5.0
- App: Mi Home / Xiaomi Home only (not compatible with Mi Fitness or other apps)
- System requirements: Android 8.0 or iOS 12.0 and later
- Material: Reinforced glass + engineering plastic
- Dimensions: 300 × 300 × 24.55 mm
- Weight: 1.45 kg
- Operating temperature: 0°C – 40°C
- In the box: Scale, user manual
- Warranty: 1-year warranty from Totot
Specifications, test conditions and safety notes come from Xiaomi UAE’s official Body Composition Scale S400 product and specifications pages. Full details are published on the Xiaomi UAE Body Composition Scale S400 specifications page.
FAQ
Is the Xiaomi Body Fat Scale S400 the same as the Body Composition Scale S400?
Yes. Body Composition Scale S400 (model MJTZC01YM) is Xiaomi’s official name; “Body Fat Scale S400” is a name some sellers use for the same scale.
Which app does the Body Composition Scale S400 use?
1 app only: Mi Home/Xiaomi Home. Xiaomi states it is not compatible with Mi Fitness or any other app.
How many people can use one scale?
36. The S400 stores up to 36 family members and recognises each one automatically within ±2 kg of their last weight.
How long do the batteries last?
Up to 180 days on three AAA alkaline batteries, based on Xiaomi’s test of three weigh-ins a day of about 45 seconds each at 25°C.
Can I weigh my baby or pet?
Yes. Baby holder mode weighs infants and pets while you hold them, and the data can be saved in the app.
Can someone with a pacemaker use it?
No. Xiaomi does not recommend it for people with implanted medical devices, and advises pregnant women to use it with caution.
Browse more in our Fitness Trackers range. Every order from Totot carries a 1-year warranty covering manufacturing defects, with our 14-day return policy for defective or non-compliant items, and nationwide UAE delivery.
Please note: The fitness and wellness sensors in this product are intended for sport and general activity tracking and are not a medical device. Readings are approximate and are not intended to diagnose, monitor or treat any medical condition. Consult a qualified doctor for any health-related decision.
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