Most accurate scale for weighing objects

[Secan]

Hello, What is the most accurate weighting scale in existence and what kind to look for if you want accuracy. The other day I got this scale. I put a known 7.6 pound book. It showed up as 7.730 lbs so I returned it. I need something that can show exactly the weight. What kinds of scale must I look for?

 

[hutchphd]

I need something that can show exactly the weight.

This statement has no technical meaning.
You need to specify what level of accuracy and precision you require and proceed accordingly. There exist scales that will meet almost any requirement. The will cost proportionally and might require periodic calibration.

 

[Secan]

This statement has no technical meaning.
You need to specify what level of accuracy and precision you require and proceed accordingly. There exist scales that will meet almost any requirement. The will cost proportionally and might require periodic calibration.

I just need the scale to show a 7.6 pound book as 7.6 pound weight. Would common scales do that? What are the errors usually. And what kind of weighting scale has such accuracy (for weighting humans)? Budget is just below $500.

 

[shjacks45]

I wonder how you know the book is 7.60 pounds? Another scale that you have calibrated, or you trust due to familiarity? Because the metric system is used in precision and scientific work, a scale in pounds probably won't be as accurate. Or specialized and more expensive. In picking a scale you need to know what accuracy you require and what range of weight you need to weigh. Digital bathroom scales are often inaccurate at low weight like your book. Scales, of course, you measure against real physical weights. My needs are to accurately measure milligram changes in 500g flasks or 99.999% accuracy, for example.

 

[Secan]

I wonder how you know the book is 7.60 pounds? Another scale that you have calibrated, or you trust due to familiarity? Because the metric system is used in precision and scientific work, a scale in pounds probably won't be as accurate. Or specialized and more expensive. In picking a scale you need to know what accuracy you require and what range of weight you need to weigh. Digital bathroom scales are often inaccurate at low weight like your book. Scales, of course, you measure against real physical weights. My needs are to accurately measure milligram changes in 500g flasks or 99.999% accuracy, for example.

I just need a very accurate baby scale with typical range of 0 to 44 lbs. And I'd use it for other things as well so i want to get the most accurate scale that can show 10kg as exactly 10kg or error of 0.5 ounce.

 

[Tom.G]

https://www.google.com/search?&q=analytical+scale+20kg

And to ensure accuracy, get a set of calibration weights, and use them periodically.

 

[shjacks45]

I just need a very accurate baby scale with typical range of 0 to 44 lbs. And I'd use it for other things as well so i want to get the most accurate scale that can show 10kg as exactly 10kg or error of 0.5 ounce.

The other day they weighed me on 3 different digital scales, at a hospital, and got 3 different weights. Baby scales and adult (diet) scales have no need to be that accurate. I'd think the maker of the scale was more concerned if a baby fell out of the "weighing pan". Both adults and babies on scales are moving so no absolute accuracy. Most consumer scales don't even have a Tare function and never a Calibrate function. Quality scales like Mettler or OHAUS are temerature compensated and calibrating with NBS referenced weights was right on (off by .0001 gram). Still have to go thru that step.

 

[Secan]

The other day they weighed me on 3 different digital scales, at a hospital, and got 3 different weights. Baby scales and adult (diet) scales have no need to be that accurate. I'd think the maker of the scale was more concerned if a baby fell out of the "weighing pan". Both adults and babies on scales are moving so no absolute accuracy. Most consumer scales don't even have a Tare function and never a Calibrate function. Quality scales like Mettler or OHAUS are temerature compensated and calibrating with NBS referenced weights was right on (off by .0001 gram). Still have to go thru that step.

Do all these scales use strain gauges or other more exotic principles like muons cross sections? What scales use such principles?

 

[Secan]

I wonder how you know the book is 7.60 pounds? Another scale that you have calibrated, or you trust due to familiarity? Because the metric system is used in precision and scientific work, a scale in pounds probably won't be as accurate. Or specialized and more expensive. In picking a scale you need to know what accuracy you require and what range of weight you need to weigh. Digital bathroom scales are often inaccurate at low weight like your book. Scales, of course, you measure against real physical weights. My needs are to accurately measure milligram changes in 500g flasks or 99.999% accuracy, for example.

Does it use strain gauges? What principle or technolgy or implementation is the most accurate ever?

 

[hutchphd]

This is a fascinating topic, but there is no simple answer to that question. Please begin here:

https://en.wikipedia.org/wiki/Weighing_scale

.