I compared a $20 smart scale with an $8,500 body composition machine and the results were surprising.

For over four months, I've been using a Vitafit smart scale to monitor my body weight. Acquiring one of the best smart scales is one of the easiest ways to track not just weight, but also key metrics like body mass index (BMI), body fat, and more. This device can provide insights into how many calories you should consume daily to lose weight, as well as assist in tracking your progress over time.

I bought my Vitafit on Amazon for around $20, and honestly, I didn’t have high expectations. However, I have been quite satisfied with its interface and features, although I’ve always had the suspicion that it might not be very accurate. The results were consistent, making the relative data useful, but I wasn't entirely convinced it was a truly accurate scale.

This questioning intensified when I tested it during a recent review. In terms of performance, the only true measure of quality for a smart scale is accuracy. I was fortunate to live near a modern gym equipped with a state-of-the-art body composition machine, so I decided to conduct a comparison. The results surprised me.

The Tanita MC-780MA P machine, worth £6,500 / $8,500 / AU$12,500, promises Japanese engineering precision and clinical accuracy. It provides over 20 body measurements, including BMI, fat mass, among others, and is classified as a Class III weighing instrument and a Class II-a medical device. In summary, it’s one of the best body composition technologies available.

I conducted a series of controlled tests between the Vitafit and the Tanita. I weighed myself on both, first on the Vitafit, then on the Tanita, and repeated the process with the Vitafit shortly after, having walked between tests. The results varied, but the accuracy of the Vitafit in some key measurements surprised me; many figures were reasonably close, while only a couple showed marked discrepancies.

Both scales shared 11 total measurements.

Regarding body weight (in kg), the Vitafit showed 107.75 kg in the first test and 107.45 kg in the second, while the Tanita gave a result of 107.61 kg. The Vitafit was only 0.15 kg off from the Tanita value on both occasions.

In terms of body fat, the Vitafit showed 26.1% in the first test and 26% in the second, compared to Tanita's 27.4%. The Vitafit seems to underestimate body fat, which could be problematic, given that high levels can increase health risks, although the opposite is also dangerous.

For lean mass (KG), the Vitafit reported 79.64 kg, continuously higher than Tanita's 78.1 kg, which seems logical given the underestimation of fat.

Bone mass was a strong point for the Vitafit, which remained within 90 grams of Tanita's value, showing 3.89 kg in both tests.

However, for muscle mass (KG), the Vitafit appeared to overestimate the value by 1.3-1.4 kg.

Visceral fat was another area of concern, with Tanita reporting a 10 and the Vitafit a notable 18, which is alarming considering the first was within a healthy range while the latter was not.

As for body water, the Vitafit reported a figure of 46.30%, but it turned out to be over 5% lower than that reported by Tanita, which is concerning given the permissible margin limits.

The Body Mass Index (BMI) was quite accurate, with the Vitafit reporting 32.2, while the Tanita showed 32.1.

The Basal Metabolic Rate (kcal) reflected a discrepancy of about 200 calories between the two, which could be explained by the use of different formulas to calculate it.

Skeletal muscle mass showed a small difference, with 41.8% on Vitafit compared to 40.1% on Tanita.

Finally, metabolic age was a very different result: 24 on Vitafit versus 44 on Tanita, which can be explained due to variations in metabolic rates.

In summary, while Tanita is more accurate and precise in comparison, I was surprised by how close the Vitafit came in several measurements. This analysis also highlights the limitations of a smart scale, especially in body composition areas where the Vitafit struggled. However, it is reassuring to see that the Vitafit provides consistent measurements, which can be useful in tracking personal progress, even if they are not completely accurate.