05 Jul 2025
WHAT ARE LOAD CELLS AND HOW DO THEY WORK?
Load cells are precision devices that are used to measure force or weight by converting a mechanical load into an electrical signal. But what are load cells, and what applications are they used in? They are commonly found in industries such as manufacturing, construction and logistics and play a critical role in ensuring accurate measurements for safety, quality, and efficiency.
This article will fully explore the different types of load cells, what their key applications are, how you calibrate them and the other factors that influence their accuracy.
WHAT ARE LOAD CELLS?
The simplest answer to the question, what are load cells? it is that they are a sensor that measures force or weight by converting electrical signals. The force/weight interacts with the sensors, giving a reading that is inversely proportional to it. This allows for impressively precise measurements.
There are a variety of load cells on the market that are all powered by different means, from electrical charge to hydraulics to air pressure.
HOW DO LOAD CELLS WORK?
Load cells operate by converting an applied force or weight into an electrical signal that can be measured and interpreted. Strain gauge technology is the most common type and is where small sensors are bonded to a structural element of the load cell. When a force is applied, the load cell deforms slightly, causing the strain gauges to stretch or compress. This deformation changes the electrical resistance of the strain gauges, which is then converted into a proportional electrical signal.
The signal is typically very small, so it is amplified and processed by electronics to provide an accurate reading of the aforementioned load. In essence, the load cell is a translation device for converting mechanical force into a measurable electrical output. This process allows for precise monitoring in a wide range of industrial, commercial and even scientific applications.
WHAT DO LOAD CELLS MEASURE?
Load cells are designed to measure different types of forces, including compression (pushing), tension (pulling), and shear (sliding or lateral forces). Asking what do load cells measure is important as accurate readings of these forces provide critical data for weighing, monitoring and controlling processes across industries.
They are widely used in manufacturing to ensure quality control, in aerospace for testing structural loads, and in agriculture for monitoring machinery and bulk materials. In the medical sector, load cells are applied in patient lifts and diagnostic equipment, while logistics and transport rely on them for weighing goods and ensuring safety. Their versatility and precision make them essential tools wherever accurate force or weight measurement is required.
COMMON TYPES OF LOAD CELLS
Strain gauge load cells
A strain gauge load cell measures force by converting that energy into an electric signal via strain gauges that can detect the smallest movements. The load cell flexes under this force and adapts its electrical resistance in proportion to the strain. This change is measured by a Wheatstone bridge circuit to accurately determine the weight/force recorded.
Hydraulic load cells
This type of cell works by using fluid to apply force via a piston. The resulting pressure change will be directly proportional to the load’s weight/force. This system is based on the principles outlined in Pascal’s Law of confined fluid pressure changes.
Pneumatic load cells
A pneumatic load cell works in a very similar way to the hydraulic load cell, but instead of using liquid pressure to determine weight, it uses air pressure. This can be a cleaner and safer option for weight detection.
Capacitive load cells
Capacitance is an object's ability to store an electric charge. A capacitive load cell detects force and weight changes by converting the changes in capacitance between two conductive plates running parallel. They are highly sensitive and have huge tolerance levels.
Piezoelectric load cells
This system features a piezoelectric material, like a crystal, that will generate an electrical charge that is proportional to the level of force it is experiencing, which can be converted into a voltage signal for precise measurements.
HOW TO CALIBRATE LOAD CELLS
Learning how to calibrate load cells is a fairly time-consuming process that requires a selection of specific tools. You will need a selection of weights or a force-generating system. A device known as a ‘master standard’ or a reference load cell. A digital indicator, a deadweight stand and a universal testing machine. Obviously, these devices will arrive from the factory pre-calibrated, but you will need to conduct ‘field calibrations’ periodically to maintain accuracy.
1. Ensure that the environment for calibration is stable, free from any vibrations (no matter how small) and consistent temperature
2. Connect the load cell to its measurement system, whether that be an amplifier or indicator, and power up the system
3. After waiting 10-30 minutes for it to warm up, check for any loose fittings or potential misalignments
4. Set the measurement to zero with no load attached
5. After zeroing the load cell, gradually add a series of known weights or set force standards in ascending increments and record the output reading (10 increments is the general recommendation)
6. Use this recorded data (input vs output) to adjust the internal calibration for offsets or slopes – some systems will need this to be done manually – the goal is to bring both values to the same level
7. Repeat this process and compare the readings – these readings should also be recorded for future reference
COMMON LOAD CELL PROBLEMS AND TROUBLESHOOTING
Common problems will include electrical issues like faulty wiring, temperature changes, vibrations and moisture damage. There can be mechanical problems like misalignment or overload damage. Some problems like signal drift, noisy readings, zero shift or other fluctuations are normally signs of underlying problems.
Essentially, what are load cells? They are measuring devices. Even everyday measuring devices like kitchen scales will become misaligned over time or susceptible to various problems.
Troubleshooting should be done by conducting visual checks to see if there are any clear wiring or connection issues. Conduct a variety of load and resistance tests, change the load cells' environment and test against another device to try and isolate the problem. If nothing becomes clear, it may be time to seek professional assistance.
HOW ACCURATE ARE LOAD CELLS?
Load cells are widely used to measure weight or force with high precision, but their accuracy is subject to specific tolerances depending on type and quality. Several factors can influence a load cell’s precision. Environmental conditions such as extreme temperatures, humidity or even vibration can cause drifts in measurement. Overloading the cell beyond its rated capacity can permanently affect its accuracy, while improper installation, including misalignment, uneven mounting or inadequate support, can introduce errors.
Regular calibration is essential to maintain reliable performance, especially with how load cells are used as a weighing system. By comparing the load cell’s output against already known reference weights, calibration ensures measurements remain within specified tolerances and accounts for potential changes over time. Proper installation, careful handling and periodic recalibration allow load cells to deliver consistently accurate readings, even in demanding industrial or laboratory environments. This makes them indispensable for applications where precise force or weight measurement is critical, from manufacturing and construction to scientific research.
WHICH LOAD CELL DO I NEED?
Now that you have the answers to what load cells are, you now need to work out which one you need. When choosing the right load cell, consider factors such as load capacity, ensuring it exceeds your maximum expected weight with a suitable safety margin. You should also note that your mounting style must match your application, whether compression, tension, shear or S-type.
Feel free to download the full Load Cells Quick Guide, or for further support, contact the team of experts here at LES® for personalised guidance.
