Every load cell on the market comes with a manufacturer’s data sheet that lists its performance capabilities. These specifications help engineers determine if a load cell meets their application’s requirements. They also serve as a performance benchmark for proper calibration or for identifying faults.
This guide explains how to read a load cell data sheet in two parts: a comprehensive table of specs with brief explanations, and a deeper dive into the most important load cell characteristics for those interested in the science behind them.
What Information Does a Load Cell Datasheet Provide?
Specs on a load cell data sheet generally cover three areas: output voltage expectations for a given load, the maximum expected error under specific operating conditions, and safe environmental and mechanical operational boundaries.
Table of Load Cell Specifications
For some terms below, it may be helpful to refer to Figure 6 in our Force Measurement Glossary. Other definitions in this resource may likewise provide some clarity.
| Specification | Units | Interpretation | Notes |
|---|---|---|---|
| Breaking Overload | % | The ultimate load limit the instrument can withstand before experiencing catastrophic structural failure. | Expressed as a total percentage of rated capacity (e.g., 300% means structural failure occurs under a load 3 times the rated capacity). |
| Combined Error | % | The maximum expected output deviation from a theoretical straight line (voltage output vs. force plot) due to the combined effects of non-linearity and hysteresis. | Expressed as a percentage of full scale output (FSO). |
| Compensated Temp Range | °C to °C °F to °F |
The temperature limits within which the load cell will maintain its zero balance and rated sensitivity specifications. | “Compensated” indicates internal temperature-sensitive resistors have been added to the circuit to offset thermal zero and span drift. |
| Creep in 30 minutes | ± % | The change in output signal occurring over time while under a constant, continuous load (typically rated capacity) with all environmental factors held constant. | Expressed as a percentage of full scale output (FSO). |
| Full Scale Output (FSO) | mV/V | The output voltage the load cell produces at rated capacity, minus the output voltage at minimum load, per excitation volt at the input terminals. | Multiply the FSO by the excitation voltage to calculate the total expected voltage swing from a zero-load state to full capacity. |
| Hysteresis Error | ± % | The maximum difference between ascending-load and descending-load output voltage readings at the exact same load point across the measurement range. | Expressed as a percentage of full scale output (FSO). |
| Input Resistance | Ω | The electrical resistance of the load cell’s internal excitation circuit. | Measured across the input terminals under no load conditions and an open circuit at the output. |
| Insulation Resistance | GΩ | The electrical resistance measured between the internal circuit bridge and the physical structure (body) of the load cell. | High insulation resistance (typically 5 GΩ or greater) prevents stray voltage leakage and signal degradation. |
| IP Rating | “IP” + 2 digits | A standardized classification indicating the level of environmental protection a load cell’s coating or structure provides against solids and liquids. | Ratings use two digits (e.g., IP68); the first digit measures solid particle protection and the second measures liquid ingress protection. See this useful graphic. |
| Non-linearity | ± % | The maximum output voltage deviation from a theoretical linear input-output plot at any load between zero and rated capacity. The comparative theoretical linear input-output function is the line from zero balance output at no load to output at max load. | Expressed as a percentage of full scale output (FSO). |
| Output Resistance | Ω | The electrical resistance of the internal output signal circuit. | Measured across the output terminals under no-load conditions with an open circuit at the input. |
| Rated Capacity | Mass or force units | Maximum load the device can bear and still perform within its rated tolerance limits. | Expressed in standard engineering units such as lbs, kg, tons, or Newtons, depending on the specific load cell’s scale. |
| Recommended Excitation | V | The optimal input voltage required to power the internal strain gauge bridge circuit. | Usually listed as a baseline value along with a maximum allowable voltage limit (e.g., 10V Recommended, 15V Max). Load cells are passive devices; therefore, all require excitation voltage. |
| Repeatability | ± % | The maximum difference between output readings when the exact same load is applied repeatedly under identical environmental and loading conditions. | Expressed as a percentage of full scale output (FSO). |
| Safe Overload | % | The maximum total load an instrument can withstand without experiencing a permanent mechanical shift in zero balance or performance beyond its specifications. | Expressed as a total percentage of rated capacity (e.g., 150% means the cell can take on a load 1.5 times its rated capacity without causing permanent deformation). |
| Sensitivity | mV/V | The ratio of the change in output signal voltage to the change in the applied mechanical load. | For an unamplified load cell, sensitivity is numerically identical to its Full Scale Output (FSO). It is a measure of signal strength. |
| Service Temperature Range | °C to °C °F to °F |
The environmental temperature limits within which the load cell can safely operate without sustaining permanent damage. | This range is wider than the Compensated range; performance errors will likely exceed standard datasheet tolerances when operating in this zone. |
| Storage Temperature Range | °C to °C °F to °F |
Ambient temperature limits while the load cell is in storage. | Storage within these limits will prevent permanent calibration shifts affecting performance when the load cell is redeployed. |
| Temperature Effect on Sensitivity | ±% of load per °C | The change in rated output (span) sensitivity caused by fluctuations in ambient temperature. | This error only impacts the reading when the load cell is under load. It represents thermal span drift. |
| Temperature Effect on Zero Balance | ± % FSO / °C | The shift in the baseline zero-load output signal caused by fluctuations in ambient temperature. | This error causes the scale’s tare or zero point to drift up or down even when the scale is completely empty. |
| Zero Balance or Zero Offset | mV/V | The electrical output signal produced by the load cell under a true no-load condition, per volt of excitation. | Tells you how far off from a perfect 0.00 mV/V the unfiltered sensor sits before first in-service calibration. |
Interpreting Key Load Cell Performance Metrics: The Science
While the specification table provides a quick reference, a deeper understanding of how certain key metrics interact in real-world applications is useful. The following sections break down the most critical performance indicators on a manufacturer’s datasheet.
Full Scale Output (FSO) and Sensitivity
On a manufacturer’s datasheet, Full Scale Output (FSO) and Sensitivity typically have the same numerical value (usually \(2.0\text{ mV/V}\) or \(3.0\text{ mV/V}\)). While they are mathematically identical, they describe the sensor from two different engineering perspectives: FSO is a measurement of mechanical span, whereas Sensitivity is a measurement of electrical gain.
Full Scale Output (FSO): The Mechanical Span
FSO looks directly at the physical scale. It defines the total signal span available across the sensor’s entire weight capacity.
- The Core Definition: The net output voltage change the load cell produces when moving from a completely unloaded state to its maximum rated capacity, measured per volt of input power.
- The Practical View: It answers the question, “What is the absolute output voltage range this sensor can swing through from a completely unloaded state to its maximum rated capacity?” Multiplying FSO by your excitation voltage gives you the exact signal span your software needs to map weight metrics accurately.
For example:
$$\text{Voltage Swing (mV)} = \text{FSO (mV/V)} \times \text{Excitation Voltage (V)}$$
Therefore, a load cell with a \(2.0\text{ mV/V}\) sensitivity powered by a \(10\text{V}\) excitation voltage will yield a net output of \(20\text{ mV}\) at full capacity.
Sensitivity: The Electrical Gain
Sensitivity describes the electronics. It reveals the efficiency of the internal Wheatstone bridge circuit as an electrical transfer function.
- The Core Definition: The slope of the line plotting output voltage (\(mV\)) against excitation voltage (\(V\)) while the load cell is under a fixed, maximum capacity load.
- The Practical View: It answers the question, “For each volt of excitation I deliver to this passive bridge, how many millivolts of differential signal will it output to my amplifier?”
The fundamental load cell output formula dictates this ratiometric relationship:
$$\text{Output Voltage (mV)} = \text{Sensitivity (mV/V)} \times \left(\frac{\text{Applied Load}}{\text{Rated Capacity}}\right) \times \text{Excitation Voltage (V)}$$
An instrumentation programmer looks at this equation through the lens of FSO to calibrate the scaling software (translating millivolts back into pounds or kilograms). Simultaneously, a hardware design engineer looks at this equation through the lens of Sensitivity to ensure that if the system’s power supply fluctuates, the output signal-to-excitation ratio remains stable and won’t clip or saturate the signal conditioner. Presenting both viewpoints ensures your system design is accurate from physical placement all the way through digital signal processing.
Combined Error, Non-Linearity, and Hysteresis
The previous section describes a perfect, linear relationship between a load cell’s input and output. In reality, the materials used in sensor construction exhibit minor deviations in their elastic behavior that affect this ideal line. Datasheets quantify these deviations using three interrelated metrics:
- Non-linearity: The maximum deviation of the output signal from a theoretical straight line drawn between zero load and rated capacity during an increasing load test.
- Hysteresis Error: The maximum difference between ascending-load and descending-load voltage output readings at the exact same weight point.
- Combined Error: A comprehensive metric where the manufacturer bounds the worst-case effects of both non-linearity and hysteresis into a single accuracy window.
Using Combined Error simplifies your system math. If a load cell has a combined error of \(\pm0.03\%\) of FSO, you can quickly calculate the maximum expected measurement deviation across the entire operating range without needing separate calculations for ascending and descending weights.
Load Cell Creep and Time-Dependent Drift
Creep is the change in the output signal that occurs over time while a load cell remains under a constant, continuous load with all environmental variables held completely steady. On a datasheet, this is typically specified as a maximum percentage of FSO over a 30-minute interval.
Creep occurs due to the microscopic, time-dependent strain properties of both the metal spring element and the adhesives bonding the strain gauges to it. Understanding creep is vital for static weighing installations—such as tank, silo, or hopper batching systems—where materials sit on the scale for extended periods before processing. If creep limits are too high, the signal will slowly drift, recording an artificial change in weight.
Temperature Effects: Thermal Zero Shift vs. Thermal Span Drift
Temperature fluctuations physically alter the electrical resistance of a load cell’s internal circuitry and the elasticity of its metal body. Datasheets break these thermal impacts into two separate metrics because they affect the measurement curve differently:
- Temperature Effect on Zero Balance: This shifts the baseline starting point of the entire measurement curve up or down. It acts as a constant, additive error that is present even when the scale is completely empty. Because it is static at any given temperature, this effect can be eliminated in the field by pressing the Tare button before beginning a measurement cycle.
- Temperature Effect on Sensitivity (Thermal Span Drift): This alters the slope or multiplier of the measurement curve. It changes how much the signal reacts per unit of force. This error is completely invisible when the scale is empty, but scales up linearly as more weight is added. It cannot be corrected by taring the scale.
Manufacturers add temperature-sensitive resistors directly into the internal bridge circuit to minimize these variations across the listed Compensated Temperature Range.
Structural Overload Limits: Safe vs. Breaking Overload
Overload specifications establish the definitive physical boundaries for protecting your equipment from unexpected forces, such as wind loads, mechanical binding, or shock loading.
- Breaking Overload: The ultimate structural limit before catastrophic physical failure occurs. A breaking overload spec of \(300\%\) means the sensor body will physically shear, buckle, or fracture at \(3,000\text{ lbs}\) of total absolute force, posing an immediate structural safety risk to the entire assembly.
- Safe Overload: The maximum total load an instrument can withstand relative to its capacity before experiencing permanent structural distortion. For instance, a safe overload spec of \(150\%\) means a \(1,000\text{ lb}\) load cell can briefly experience a total absolute load of \(1,500\text{ lbs}\). Exceeding this limit will cause a permanent mechanical shift in the zero balance, requiring recalibration or component replacement.
Conclusion: How Load Cell Specifications Apply to Your Project
It may seem somewhat intuitive, but applying the numbers in the spec sheet simply amounts to making sure the performance they describe matches the requirements of your project. Can the load cell operate in the ambient temperatures where it would function? Can it handle the humidity and particulate matter where the weigh system operates? Is the sensitivity appropriate for my output device? (See “How does a load cell’s sensitivity relate to the display or interface I choose?” in our FAQs.) These and similar questions make knowing how to read a load cell data sheet important to any weigh system design.
For more information on these data sheet specifications, see What is the Lowest Weight a Load Cell Can Measure?. For more guidance on selecting weigh system components, see our popular article, Choosing the Right Load Cell for Your Job. Or use our contact form to request project-specific consultation.
