Why Do Scales Give Different Readings

Why Scales May Not Be Accurate

Are you dealing with a scale that tells you that you weigh 188 pounds in the morning, 200 pounds in the afternoon and 50 pounds at night? That can be frustrating. So what could be the matter with your scale?

Before we dig into some reasons why your scale may be inaccurate, let's state that some scales are just plain substandard and poorly manufactured. Therefore, they were built to malfunction. If that's the kind of scale you have, then you may have to dump it in the garbage and buy a better one.

But sometimes, even a good scale can give inaccurate readings for other reasons like the scale is old and is malfunctioning due to wear and tear.
Even brand new scales can be inaccurate in extreme hot or cold temperatures, which is why you need a scale with excellent temperature stability. New scales could also misbehave due to vibration from mishandling and rough conditions.

Also, electronic scales may become increasingly inaccurate if there is a circuit defect within it. 

Factors that can affect the performance of your scale

1. Environmental Factors

As we started to say above, the conditions within which your device has to work could affect its accuracy.

Shock loading: When you dump heavy-duty items on your scale without regard for its maximum weight capacity, it damages the load cells. You won't like the results that follow.

Vibration: If your unit is beside or close to another working piece of machinery, sensitive loads can misread the vibrations from the machinery, which will result in an inaccurate reading.

Unrelenting wind: Your device can be affected by massive air movement even if it’s indoors. This includes air produced from air conditioners or smoke from generator exhausts (if outdoors).

Dirty scales: If you do not regularly clean your unit, dirt and other particles will collect and become an extra weight on it and underneath. If you have not cleaned your scale in two years, there is by now such a collection of strange material beneath it that whatever you place on it will not be fully supported by the load cells. And you will consistently get an inaccurate reading.

Differences in Air Pressure: If the air pressure from the operating environment is different from the internal calibration environment, inaccurate readings can follow.

2. Load Cell Accuracy

You've heard us mention load cells a few times so far. That's because the load cells are the most critical function in your digital kitchen scale or whatever kind of unit you have. Therefore, malfunctioning load cells will undoubtedly result in inaccurate weight readings.

3. Load-related Issues

An incorrect digit may also come from the load itself and the way it was positioned and supported. To load your scale correctly, make sure that the load is well aligned and that the mounting hardware is working well. If the legs of the scale are fragile and give way under heavy load, use cross braces for extra support.

4. Undue Interference

Anything that comes between the load cells and the electrical signals they transmit for display on the digital indicator will lead to inaccuracy.

Temperature and moisture are the most typical culprits behind this interference, especially for electrical scales. When temperatures rise, there is also a parallel rise in wire resistance and this causes the voltage of your device to drop leading to malfunction and misleading number displays.

Secondly, every so often, moisture builds up on the load sensor of your device, which affects electrical outputs and causes interference in the signals that the load cells transmit for display.


  • Q1
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Are digital scales more accurate than Doctor’s scale?

The simple answer is no. Balance beam scales, also known as Physician's or Doctor's scales, are typically more accurate than digital scales.

But if you own a doctor's scale that you haven't cleaned in twenty years, I can tell you for free that it will not be an accurate scale. Food for thought, hmm?

In that case, a digital scale that is in excellent condition will give a more accurate reading.  What you need to do is recalibrate your Doctor's scale, and everything’s going to be alright.

About the Author Harry Thompson

Gaining a BSc Honours in building/ property maintenance at the University of Portsmouth Harry went into the field of renovating properties. Along the journey, he has developed a wide variety of home & garden DIY skills such as installing new kitchens and landscaping gardens.