Flexiforce pressure sensor or force sensitive resistor “FSR” Programming & calibration using Arduino

(Last Updated On: February 13, 2020)



This Tutorial is about the FlexiForce sensor. In this tutorial I will show you the easiest and simplest way how to calibrate the flexiforce sensor, During the calibration, we will be measuring some known weights with this sensor, I personally don’t recommend using flexiforce sensor for weight measurement, for weight measurement load cell is the best choice, I have very detailed tutorials on weight measurement using load cell and hx711 “Click Her” if in case you want to watch this tutorial. In this tutorial, I will be using weights only for demonstration purposes. This tutorial covers the extreme basics, how to use the flexiforce sensor with Arduino, while in the upcoming tutorials we will be using this sensor in security-based projects, we will also be using this sensor in a plastic injection molding machine for pressure monitoring, we will also be using this in robots.

For the step by step explanation, you can watch a video Tutorial “Click Here

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FlexiForce Sensor:


A flexiforce sensor is also known as the force Sensoring Resistor. The Flexiforce sensor or force sensing resistor is made up of such type of material whose resistance changes when a force or pressure or mechanical stress is applied. A flexiforce sensor is also known as force sensitive resistor “FSR”.

As you can see clearly in the picture, the flexiforce sensor has three legs or pins. The middle one is not used.

The circular area of the sensor is the effective area of the sensor, where the force or pressure will be applied. To apply the force or pressure exactly at this area I cut a piece of hard rubber in a circular shape and fix it using hot glue. Now our sensor is ready.

Circuit Diagram:


FlexiForce sensor is connected in series with a 10k resistor, you can try some other resistors like 1 megaohm or 3.3k if you want to measure high force or high pressure. The Flexiforce sensor and the 10k resistor makes a voltage divider, this way for different forces or pressure values we will get different voltages.

From this voltage variation which is due to the force or weight, we can calculate the weight in pounds or kgs. So make sure you have some known weights, I have 1kg and 3kg weights which I will use for the calibration. A 47uf capacitor is connected in parallel with the 10k resistor, you can use a small value capacitor, the purpose of this capacitor is to stop the voltage fluctuation and get stable values. We will read these voltages using the Arduino’s analog pin A0. Once again if you want to measure high pressure or weight then use a small value resistor.

For the Flexiforce sensor interfacing watch video Tutorial “Click Here


Arduino FlexiForce sensor programming

for the step by step program explanation watch Video Tutorial “Click Here

Watch Video Tutorial:


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About the Author: Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

1 Comment

  1. What an awesome post ! Thanks you for sharing such a great content. Just one question, do you know if this method is valid por sensors like ‘SF15-600@10kg from LEANSTAR’ ? and do you know any multiplex or devices to define something like a bus of sensor in order to use just one arduino ? thanks you in advance, keep on it !

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