When we’re talking about load cell accuracy, what we’re really after is trust. A load cell needs to be able to tell the truth every time it’s put to the test, under any condition it was designed to handle.
And accuracy isn’t just some single number; it’s the result of a bunch of different performance characteristics all working together. Two of the most important ones are nonlinearity and repeatability.
These two factors are related, but they’re not the same thing. Understanding how they do or don’t interact can be a big help to engineers when it comes to troubleshooting systems, improving performance, and choosing the right load cell for the job at hand.
What Do We Mean by Load Cell Accuracy?
Load cell accuracy is all about how well the sensor’s output reflects the actual load being applied. This depends not only on factors like linearity, hysteresis, repeatability, creep, temperature effects, signal noise, and installation quality but also on the sensitivity of the load cell, which is its ability to detect small changes in force reliably.
Each of these factors affects performance in different ways, influencing both the accuracy and reliability of the load cell’s measurements. Among the many factors, two of the most important are nonlinearity and repeatability, because they have the greatest impact on whether the sensor can provide consistent, trustworthy readings under real-world conditions.
Nonlinearity: A Matter of Shape
Ideally, if you were to plot a load cell’s electrical output signal against the load that’s being applied, you’d get a perfect straight line. But in the real world, things don’t work quite so neatly.
Nonlinearity measures how much the actual response curve deviates from that ideal straight-line relationship.
Morehouse, a leading load cell laboratory, does a great job of explaining this – and they note that nonlinearity is typically expressed as a percentage of full-scale output, like ±0.02% FS.
Why Nonlinearity Happens
- Manufacturing tolerances in the strain gauges
- The elastic properties of the materials used
- Slight variations in the beam geometry or the way it’s machined
The key thing to keep in mind here is that nonlinearity affects accuracy right across the full working range of the sensor.
Repeatability: A Matter of Consistency
Repeatability is all about asking one question: If we apply the same load repeatedly under the same conditions, will the sensor output the same value each time?
A load cell with high repeatability will produce consistent readings even if the relationship between the load and the cell output isn’t perfectly linear.
What Affects Repeatability
- The quality of the mechanical mounting and seating
- Temperature variation
- Electrical noise and grounding quality
- Micro-movements in the structures or frames
Repeatability can’t be corrected through calibration. If a sensor behaves differently every time, no calibration curve can predict or compensate for that uncertainty.
The key thing to keep in mind here is that repeatability affects usability, especially in things like batching, dosing, or closed-loop control.
How Nonlinearity and Repeatability Influence Each Other
Even though they’re measured separately, these two specifications interact in meaningful ways.
| Property | What It Describes | Where It Matters Most |
| Nonlinearity | Deviation from ideal straight-line output | Accuracy across the full load range |
| Repeatability | Whether repeated measurements match | Consistency of point-by-point readings |
Here’s the important relationship:
- Nonlinearity can often be corrected through calibration – because it’s predictable.
- Poor repeatability can’t be – because inconsistency is unpredictable.
So, if there’s one specification that deserves extra attention when evaluating a load cell, it’s repeatability.
Maintaining Load Cell Accuracy in Real Installations
Even a perfectly built load cell can lose accuracy if it’s installed incorrectly.
To Protect Accuracy:
- Make sure you get the mounting and alignment right. The load needs to travel through the sensor the way it’s designed to.
- Manage environmental conditions. Keep the load cell within its compensated temperature range.
- Minimize noise interference. Use shielded cables and high-quality instrumentation.
- Calibrate regularly. Calibration helps to map out nonlinearity and restore force measurement accuracy.
- Avoid overload or shock loading. Permanent damage can affect both load cell linearity and repeatability.
What Drives Load Cell Accuracy
Nonlinearity and repeatability are two of the most influential contributors to load cell accuracy. Understanding the difference helps to ensure that systems are designed, installed, and maintained to produce reliable, trustworthy results:
- Nonlinearity affects how close the measurement is to ideal.
- Repeatability affects how consistent the measurement is over time.
The measurement of the accuracy of load cells isn’t just one correct number but instead it’s the system’s ability to tell the truth again and again, across thousands of cycles.
Learn More and Speak with Our Load Cell Experts Today
Massload designs and manufactures Canadian-built load cells that are optimized for real-world stability, long-term reliability, and repeatable measurement performance.
Need support with a weighing application or performance troubleshooting? We’re here to help. Talk to our engineering team today!
