In the world of scales and balances, sensitivity, resolution, and accuracy are distinct but related characteristics that describe how the scale performs. Here’s how they differ:

1. Sensitivity (Also known as Readability)

• Definition: The smallest displayed weight change that causes a detectable scale or balance output change.
• Purpose: Indicates how responsive the scale is to small changes in weight.
• Example: If a scale has a sensitivity of 0.01 g, it will detect a 0.01 g increase or decrease in mass. It will read in increments of .01g from 0.00 throughout its capacity.

Sensitivity is the scale’s ability to “feel” tiny weight changes.

2. Resolution

• Definition: The total number of divisions a scale or balance can display or differentiate.
• Calculation: To calculate a scale of balance’s resolution, divide the capacity by the sensitivity.
• Example: If a lab balance has a 1000 g capacity and has .01 g sensitivity, you would calculate 1000 / .01 = 100,000 divisions, giving it a resolution of 1:100,000, said as “One part in 100,000”. If a floor scale has a 5000 lb capacity and 1 lb sensitivity, you would calculate 5000 / 1 = 5000 divisions, giving it a resolution of 1:5000, as “One part in 5000”. Lab balances with a force restoration load cell typically have higher resolution than bench or floor scales with a typical analog strain gauge load cell.  

3. Accuracy

• Definition: The closeness of the scale’s displayed weight to the true or known weight.
• Purpose: Tells you how correct the measurement is.
• Calculation: To calculate a scale or balance’s deviation and accuracy, divide the error by the capacity, then multiply by 100 to give you the deviation in percentage. Subtract that from 100 to give you the percentage accuracy.
• Example: If a 100 g standard weight is placed on a scale and it reads 99.8 g, the scale has an error of 0.2 g, meaning its accuracy is ±0.2 g. In terms of percentage, the deviation is .2%, and the accuracy is 99.8%.
  • (.2/100)x100=.2% deviation. 100% - .2% deviation = 99.8% accuracy.

When purchasing a scale or balance, our sales team at AAA Weigh will ask you about capacity and sensitivity requirements and discuss your accuracy goals. Resolution isn’t something we will always ask you about, but we will always keep it in mind when helping you choose the right weighing solution for your company.

If you want to discuss scale or balance sensitivity, resolution, or accuracy or need help selecting a scale or laboratory balance, Click Here to contact AAA Weigh or Call us Toll-Free at 800-394-6622.