Why Does My Digital Scale Give Inconsistent Readings?

Does your digital scale give inconsistent readings when weighing the same or identical items? Whether you’re weighing in a lab, kitchen or warehouse, this blog reviews the most common causes for inconsistent readings, as well as how you can resolve each issue.

Weighing Units

Ensure you’re using the same weighing units during both weighing sessions. It can be easy to switch from grams to ounces by accident or forget to switch back when weighing different items. This can lead you into believing the readings are inconsistent. You're simply portraying them a different way!

Digital Scale Lacks Stability

When digital scales are unstable, you can see fluctuations in the readings. This is due to uneven weight distribution of the items on the pan. Place your digital scale on as flat and stable a surface as you can manage. Then, use the built-in leveller and adjustable feet to ensure the scale itself is as even as possible. This will prevent rocking or certain areas of the pan withstanding more weight than others.

Environmental Fluctuations

The environment around you can impact your balance and lead to inconsistent readings, including:

• Air drafts
• Vibrations
• Direct sunlight

Are you outdoors, near a window or right under the building’s heating and cooling system? Air drafts could be causing the inconsistent readings. Attempt to keep your balance blocked from air currents. Ensure you're closing the draft shield completely before recording your results.

Look out for vibrations from the HVAC system, construction down the street or even a large lorry lumbering down the road. Your balance could be picking it up. Anti-vibration tables neutralise these tremors so you can weigh more effectively.

Finally, keep your digital scale or balance away from direct sunlight. It can begin to heat up the glass, plastic and metal, causing inconsistent readings.

Sample Inconsistency

If you weigh a hot object and then weigh it again when it’s cooled, you might notice two different readings. This is because the sample has fundamentally changed. Likewise if you’re weighing an item while it’s damp as opposed to when it’s dry. To get the best results when weighing more than once, your samples should be in the same state both times.

Calibrating Your Digital Scale

If you’ve ruled out stability, environment and sample consistency, consider the last time you calibrated your digital scale or balance. When a digital scale is out of calibration, you could see results begin to drift, jump or become inconsistent. We recommend calibrating before important weighing sessions (particularly if you’re using a balance), after moving the digital scale to a different location, and after bumping or jostling the digital scale. There's really no such thing as calibrating a digital scale or balance too often – calibrating often is recommended, especially for machines with a fine readability.

It’s also important to note that semi-micro and analytical balances benefit from “warming up” in a new environment before being calibrated or used at all. Place it in its new environment about 12 hours before you need to start weighing so it can acclimate to the space.

Tare or Zero

Inconsistent readings could be caused by misuse of the Tare or Zero buttons. For example, taring out a weigh boat when weighing one sample of powder, but forgetting to retare when using a different weigh boat. The difference may be minimal and seem like inconsistent readings.

When you’re done weighing, the display should show a zero value when there’s nothing on the pan. If there's still a reading, yau could have stored a tare weight in your digital scale’s memory, and you should Zero it out. If you leave it on, the next time you weigh will have a stored tare value subtracted from your results, which would also lead to inconsistent readings!

Using the Right Digital scale for the Job

If you just can’t get consistent readings, it may ultimately be that you’re not using the best digital scale or balance for the job. For example, semi-micro balances may offer five place results, but they’re also much more sensitive than others and it can be more difficult to get valuable results without proper prep. Consider what readability you truly need to do your job and meet regulatory requirements – you may be going too precise!

Need help figuring out the right digital scale or balance for you? Contact the Inscale team, we can help!