Every body metric your Fitdays smart scale can measure, what each one means, the BMI reference table and formula, and which metrics are model-dependent.

Measurable Parameters

Your smart scale uses Bioelectrical Impedance Analysis (BIA) to estimate body composition. A safe, imperceptible current passes through your body via the electrodes under your feet (and, on handle models, through your hands). The scale measures the resistance your tissues offer to that current and combines it with the personal data you entered in the Fitdays app — gender, date of birth (age), and height — to calculate a full set of health metrics.

Enter your profile correctly

These metrics are only as accurate as your profile. If your gender, birth year, or height is wrong in the app, the formulas produce wrong results. See Set Up the Scale and Connect the Fitdays App.

The exact list of parameters depends on your model. Basic 4-electrode foot scales measure the full BIA set below. Some models add heart rate, heart index, and body balance; 8-electrode handle models add segmental (per-limb) fat and muscle analysis. Where a metric is not available on every model, it is marked below.

Fitdays measurement details screen listing all metrics

What gets measured

The scale itself shows a few key numbers on its display; the Fitdays app shows the complete set — "More than 20 Types of Body Data" on some models. Tap More data / Details on the measurement screen to see every parameter.

Core metrics (all models)

Parameter	What it tells you
Weight	Your total body weight, in kg, lb, or st (jin on some China-market models). The primary reading shown on the display.
BMI (Body Mass Index)	An internationally used standard for judging whether your weight is healthy for your height. See the BMI formula and table below.
Body Fat Rate	The percentage of your total weight that is fat.
Fat-free Body Weight ("Without fat")	The weight of everything in your body that is not fat — muscle, bone, water, organs. Called "Without fat" on some models.
Subcutaneous Fat	The fat stored just under the skin, shown as a percentage.
Visceral Fat	The fat surrounding the organs in your abdomen, shown as an index value.
Body Water Rate	The percentage of your body made up of water.
Muscle Mass	The total weight of muscle in your body.
Skeletal Muscle Rate	The proportion of skeletal (voluntary) muscle, shown as a percentage.
Bone Mass	The estimated weight of bone (mineral content) in your body.
Protein	Your body's protein content, shown as a mass and/or a percentage on some models.
BMR (Basal Metabolic Rate)	The number of calories (Kcal) your body burns at complete rest to keep basic functions running.
Body Age	An estimate of how old your body is metabolically, compared to your actual age.

Some models also report Standard Weight (the ideal weight for your height), Muscle Rate, Protein Rate, and a Degree of Obesity value derived from the metrics above.

Model-dependent metrics

These appear only on scales that support them. Check your specific model.

Parameter	What it tells you	Availability
Heart Rate	Your pulse in beats per minute (bpm). A heart icon flashes on the scale and in the app while it measures; stay still and quiet for an accurate reading.	Heart-rate models only. The reading lengthens measurement time (about 10–20s).
Heart Index	A cardiac output index, shown as L/Min/M² (for example, 4.2 L/Min/M²).	Heart-rate models only.
Body Balance	A left/right weight comparison. The scale shows your Left weight and Right weight (for example L: 18.35 kg / R: 17.95 kg, 50% / 50%); you get about 5–10 seconds to shift and try to equalize the two sides.	Body-balance / "Posture" models only.
Segmental (Partial) Body Fat & Muscle	Fat and muscle broken down per limb — left/right arm and left/right leg — versus the standard ratio.	8-electrode handle models only (hand electrodes required).
Height record	Stores height information for users under 16, who get a weight-only measurement (body composition is not calculated for minors).	Models with the height-record feature.

Body balance test showing left and right weight

App body diagram with left/right arm and leg analysis

Socks vs. barefoot

Whether a parameter can be read depends on contact with the electrodes. If you step on with socks or shoes, the scale measures only Weight and BMI. For the full body-composition set, you must stand with bare, dry feet (and grip the handle, on 8-electrode models). See How to Measure.

BMI (Body Mass Index)

BMI is an internationally used standard for judging body fatness and whether your weight is healthy for your height. It applies to both men and women.

Formula:

BMI = Weight (kg) ÷ Height² (m²)

Worked example:

BMI = 70 kg ÷ (1.75 m × 1.75 m) = 22.86 — within the healthy range.

BMI reference table

The categories below apply to adults aged 18–100 (printed as 18–120 on some models). Source: based on standard BMI ranges (some app screens cite www.cdc.gov).

Category	BMI range
Underweight	< 18.5
Healthy weight	18.5 – 23.9
Overweight	24 – 27.9
Obesity	28 – 34.9
Severe obesity	≥ 35

A simplified BMI scale is shown inside the app on some models, labeled Thin / Standard / High / Too High with markers at 18.5, 25, and 27. The detailed table above is the reference used by the scale.

Body Type Assessment

Many models display Body Type Assessment — a row of color-coded standing-person icons (commonly five, in a blue-green-orange-red gradient) at the bottom of the screen, or a colored gradient bar on color-display models. It classifies your overall build by combining your weight with your body fat and muscle levels, giving you an at-a-glance sense of your physique rather than a single number. The highlighted icon indicates your current body type.

Where each metric appears

On the scale display: the model's headline metrics — typically Weight, BMI, Body Fat Rate, Body Water Rate, Muscle, Bone Mass, and (where supported) Heart Rate and the Body Type bar/icons. The exact layout varies by model; see Product Overview and Indicators and Errors.
In the Fitdays app: the complete parameter set, plus trend charts, a body-composition analysis report, and a body score (for example 79.7/100) on some models. See App Features and Fitdays App Functions.

All measurement data is for reference and informational purposes only and is not a medical diagnosis. Accurate readings may not be possible for some users (for example minors, professional athletes, pregnant women, or people with a pacemaker). See Cautions and Safety.

If a body-composition value is missing or shows dashes after weighing, see No Body Fat Data and Incorrect Fat/Muscle Ratio.

Measurable Parameters

Enter your profile correctly

These metrics are only as accurate as your profile. If your gender, birth year, or height is wrong in the app, the formulas produce wrong results. See Set Up the Scale and Connect the Fitdays App.