# How to Read a Load Cell Data Sheet

## Preface

Every load cell on the market comes with a manufacturers’ data sheet. It lists the load cell’s performance specifications needed to determine if it meets an application’s requirements. These performance metrics also matter when determining if a load cell calibrates properly or is faulty.

So what is on a load cell data sheet? It gives the load cell model’s specifications, which generally cover three things: (1) what output voltage can you expect for a given load, (2) how much error can you expect for a given output and (3) how to safely operate the load cell. To give insight on how to interpret them, some of the most common load cell manufacturer’s specifications are explained below.

## Table of Load Cell Specifications

Specification | Units | Interpretation | Notes |
---|---|---|---|

Breaking Overload | % | The amount of load over the rated capacity the load cell can withstand before it achieves structural failure. | Expressed as a percentage of rated capacity. |

Combined Error | % | The maximum output voltage deviation from linearity of any load between zero and rated capacity due to hysteresis and non-linearity | Expressed as a percentage of rated output. |

Compensated Temp Range | °C to °C °F to °F |
The temperature range over which the load cell is compensated to maintain rated capacity and zero balance within specification limits. | |

Creep in 30 minutes | ± % | The maximum deviation of output voltage when measuring rated capacity twice under identical environmental conditions 30 minutes apart. | Expressed as a percentage of rated output. |

Full Scale Output | mV/V | The output voltage the load cell produces at rated capacity per excitation volt at the input terminals, minus the output voltage at minimum load. | The output voltage at rated capacity is calculated by multiplying the full scale output by the excitation voltage. |

Hysteresis Error | ± % | The maximum deviation of output voltage of a load measurement taken twice: once while increasing the load from zero to rated load and once while returning the load back to zero. | Measurements are taken as close in time as possible. Error is expressed as a percentage of rated output. |

Input Resistance | Ω | The resistance of the excitation circuit. | Measured under no load conditions and an open circuit at the output. |

Insulation Resistance | GΩ | Minimum resistance between the body of the load cell and any electrical wires connected to it. | The larger the insultation resistance the better. |

IP Rating | IP68 | An indication of how resistant an electrical device is to fresh water and common raw materials like dirt, dust and sand. | IP68 devices are protected from immersion in water at a depth of more than 1.5 meters for 30 minutes. |

Non-linearity | ± % | The maximum output voltage deviation from linearity of any load between zero and rated capacity. The comparative linear plot is the line from zero balance output at no load to output at max load. | Expressed as a percentage of the rated output. |

Output Resistance | Ω | The resistance of the output voltage circuit. | Measured under no load conditions and an open circuit at the input. |

Rated Capacity | t, kg, lb, etc. | Maximum load the cell can bear and still operate within spec. | Expressed in mass/weight units depending on scale of load cell. |

Recommended Excitation | V | Recommended DC input voltage to the excitation circuit. | Frequently given as a recommended value and a max value. |

Repeatability | ± % | The maximum output voltage deviation of a given load for repeated readings. | Measured under identical loading and environmental conditions. |

Safe Overload | % | The amount of load over the rated capacity the load cell can withstand before it experiences a permanent shift in performance beyond its specifications. | Expressed as a percentage of rated capacity. |

Sensitivity | mv/V | The ratio of output voltage to excitation voltage at rated capacity load. | Indicates the smallest amount of force detectable by the load cell. The higher this voltage change, the greater the load cell’s resolution will be. |

Service Temperature Range | °C to °C °F to °F |
Temperature range over which the load cell, while in use, will meet the specs in the data sheet. | |

Storage Temperature Range | °C to °C °F to °F |
Ambient temperature range allowable while the load cell is in storage, such that it will not experience a shift in performance beyond its specifications when it resumes service. | |

Temperature Effect on Sensitivity |
±% of Cn/k | The change in sensitivity due to a change in ambient temperature | Expressed as a percentage change in sensitivity per degree Kelvin. |

Temperature Effect on Zero Balance |
± % of Cn/k | The change in zero balance due to a change in ambient temperature. | Expressed as a percentage of rated output per degree Kelvin. |

Zero Balance | mV/V | The output voltage the load cell produces per volt of excitation at no load. | The output voltage at zero balance is calculated by multiplying the zero balance by the excitation voltage. |

## 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. For more guidance on selecting the right load cell for your project, see our popular article on the subject, Choosing the Right Load Cell for Your Job.