SparkFun Load Cell Amplifier - HX711

The SparkFun Load Cell Amplifier is a small breakout board for the HX711 IC that allows you to easily read load cells to measure weight. By connecting the amplifier to your microcontroller you will be able to read the changes in the resistance of the load cell, and with some calibration you’ll be able to get very accurate weight measurements. This can be handy for creating your own industrial scale, process control or simple presence detection.

This version of the SparkFun Load Cell Amplifier features a few changes that you specifically asked for! We have separated the analog and digital supply, as well as added a 3.3uH inductor and a 0.1uF filter capacitor for digital supply.

The HX711 uses a two-wire interface (Clock and Data) for communication. Any microcontroller’s GPIO pins should work, and numerous libraries have been written, making it easy to read data from the HX711. Check the hookup guide below for more information.

Load cells use a four-wire Wheatstone bridge configuration to connect to the HX711. These are commonly colored RED, BLK, WHT, GRN and YLW. Each color corresponds to the conventional color coding of load cells:

  • Red (Excitation+ or VCC)
  • Black (Excitation- or GND)
  • White (Amplifier+, Signal+ or Output+)
  • Green (A-, S- or O-)
  • Yellow (Shield)

The YLW pin acts as an optional input that is not hooked up to the strain gauge but is utilized to ground and shield against outside EMI (electromagnetic interference). Please keep in mind that some load cells might have slight variations in color coding.

Note: Special thanks to Bodge for supplying the Library for the HX711!

Get Started with the HX711 Load Cell Amplifier Guide

  • Operation Voltage: 2.7V–5V
  • Operation Current: < 1.5mA
  • Selectable 10SPS or 80SPS output data rate
  • Simultaneous 50 and 60Hz supply rejection

SparkFun Load Cell Amplifier - HX711 Product Help and Resources

IoT Weight Logging Scale

May 9, 2018

This tutorial will show you how to make a scale that logs your weight to a custom website on the Internet. The principles can be extrapolated to any type of data.

Getting Started with Load Cells

June 11, 2015

A tutorial defining what a load cell is and how to use one.

ESP32 Thing Hookup Guide

October 27, 2016

An introduction to the ESP32 Thing's hardware features, and a primer on using the WiFi/Bluetooth system-on-chip in Arduino.

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Use the power of a Windows 10 UWP app to control and monitor a kegerator to keep your beverages cold, fresh and always on tap.

Core Skill: Soldering

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1 Soldering

Skill Level: Noob - Some basic soldering is required, but it is limited to a just a few pins, basic through-hole soldering, and couple (if any) polarized components. A basic soldering iron is all you should need.
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Core Skill: Programming

If a board needs code or communicates somehow, you're going to need to know how to program or interface with it. The programming skill is all about communication and code.

2 Programming

Skill Level: Rookie - You will need a better fundamental understand of what code is, and how it works. You will be using beginner-level software and development tools like Arduino. You will be dealing directly with code, but numerous examples and libraries are available. Sensors or shields will communicate with serial or TTL.
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Core Skill: Electrical Prototyping

If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.

3 Electrical Prototyping

Skill Level: Competent - You will be required to reference a datasheet or schematic to know how to use a component. Your knowledge of a datasheet will only require basic features like power requirements, pinouts, or communications type. Also, you may need a power supply that?s greater than 12V or more than 1A worth of current.
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Customer Comments

  • Review: The HX711 is THE “Mighty Might”! We can’t say enough about this little wonder. The only problem we found was with the omission of one little important item in the documentation and that has to do with increasing the data output rate (at the expense of sample rate/accuracy which we have proven is negligible). The board as supplied has an existing trace between the two solder pads immediately above TRACE and this trace needs to be cut to enable 80 SPS (RBB01). This was required to log the very fast data coming from our Sugar Rocket Motor Data Logger Test Bench. We are capturing a reading every 50 milliseconds and using SparkFun’s 10Kg load cell With this we are able to replicate the published data of store bought rocket motors; completely validating what the HX711 can do! The next project I used this on was to measure to a ridicules .01 gram accuracy (utilizing a 300g load cell pulled from a 20$ scale) and also control a stepper motor (stepper motor stops when target weight is reached), all with amazing consistency too! There is absolutely no difference between what you can measure with an HX711 and an expensive digital weigh scale. The BIG difference is that the MIGHTY HX711 can do a lot more & it’s inexpensive too! Buder Rocket Boys (mastering the art of sugar rockets)

  • Works well for me with a Raspberry Pi. I wrote some threaded C++ code to read weights repeatedly into an array. I also wrote a Python wrapper so you can do that from a Python/C module. Just got around to putting code on GitHub.

    https://github.com/jamieboyd/GPIO_Thread

    We used it to log data for mice

    https://github.com/jamieboyd/AutoMouseWeight

  • I have a load cell that requires 5 to 10V of power supply. Can I still use HX711? What if I push the power supply to 6V? Will it burn the board?

  • Is there a way to use this with 6 load sensors? I’ve seen the load sell combinator board, but obviously, that only works if you have 4 load sensors, right? Is there a way to do this with 6?

  • Getting the following compile error from Arduino IDE. Library used id from https://github.com/bogde/HX711

    In file included from Loadcell_Sparkfun_code.ino:34: C:\Users\Jeremy\Documents\Arduino\libraries\HX711/HX711.h:16: error: ISO C++ forbids initialization of member ‘OFFSET’ C:\Users\Jeremy\Documents\Arduino\libraries\HX711/HX711.h:16: error: making ‘OFFSET’ static C:\Users\Jeremy\Documents\Arduino\libraries\HX711/HX711.h:16: error: ISO C++ forbids in-class initialization of non-const static member ‘OFFSET’ C:\Users\Jeremy\Documents\Arduino\libraries\HX711/HX711.h:17: error: ISO C++ forbids initialization of member ‘SCALE’ C:\Users\Jeremy\Documents\Arduino\libraries\HX711/HX711.h:17: error: making ‘SCALE’ static C:\Users\Jeremy\Documents\Arduino\libraries\HX711/HX711.h:17: error: ISO C++ forbids in-class initialization of non-const static member ‘SCALE’

    Anyone encounter this?

    • What Arduino version and board definition are you using? I was able to install and use that library on 1.6.11 without issue.

      • Updated to 1.7.11 and compiles fine, but now my arduino isn’t recognized by the IDE. Arduino Uno shows up in my “Other Devices” under Device Manager, but I can’t install the driver!

        Windows gives me this when I point it to the driver folder and try to install:

        “windows found driver software but encountered an error while attempting to install it. One of the installers for this device cannot perform the installation at this time”

        Never seen this before in my life, been searching relentlessly online for solutions.

  • The formula for the output voltage AVDD appears wrong in the HX711 datasheet and the SparkFun schematic. I think it should be VAVDD = VBG*(R1+R2)/R2 … not R1 in the denominator. My derivation and measurements support this. I had to dig into this to use VSUP = DVDD = 3.3 V and change the 20 KΩ resistor to a 10 KΩ for a different load cell excitation voltage.

  • To second RobotRacer’s comment, I too would be interested to know where I can find the bare IC so I can use it on my own PCB. I’d buy one from SparkFun if they sold it on its own.

  • Will this work with a pressure sensor where all 4 legs of the wheatstone are variable?

  • Every load cell I try on this thing drifts waaay more than it’s rated - as much as 2% of FS. It seems to drift most with slight temperature changes (10 to 20 deg F). Anyone else having this problem?

  • Any idea what the maximum output impedance of the sensor can be? Those 100 Ohm resistors makes me think it has to be pretty small.

    I have a pressure sensor that’s basically a load cell but the output impedance is 1.5K.

    • 1.5k should be fine. The load cells I’ve used are a little under 2k. The 100 ohm resistors, in conjunction with the 0.1uF capacitor help to reduce noise on the input.

  • Has anyone had any luck finding the HX711 bare IC available anywhere? We are looking to integrate one into a new PCB, up to now we have been using the first version of this board (works great!!!!!!!) for prototyping. We are just ready to make the next step with development and can’t find this chip on SparkFun, DigiKey, Mouser or Arrow. We bought a bunch of these boards and stripped them just to populate some of our boards

    We love using spark fun breakouts for prototyping!

    • Have you tried sending Avia Semiconductor an e-mail and asking them who their U.S. Distributors and/or Reps are? (There are a number of U.S. companies that act as “factory reps” for various manufacturers – my experience is that they’ll be glad to answer “where can I get” questions for companies on their line-card, especially if they know you’re trying to incorporate it into a “product”.)

      Google turned up that the English web page for Avia Semiconductor is http://www.aviaic.com/enindex.asp

      Also, depending on the quantity you’re looking for, you might try asking the “volume sales” at SparkFun – it seems to me that they might be willing to sell you some (at a mark-up from what they pay, of course). The worst they can do is say “no”! (Remember, there’s an old Indian saying “If you don’t ask, you don’t get!” The old Indian who said it was named Gandhi.)

    • AliExpress has some suppliers (I found one with this title: “50PCS HX711 HX711 SOP16”) for only a few bucks.

  • Can I use Three or more HX711 modules each with separate loadcell with a single arduino UNO or mega at a time and make some algebraic sums to find out the total force acting the load cells

Customer Reviews

4.4 out of 5

Based on 30 ratings:

Currently viewing all customer reviews.

Small and simple.

It gets the job done. The labels are clear and easy to read. The example code had only one minor issue: include <name> vs include “name” and worked just fine after it was resolved. Thanks for a nice web site with all the cool stuff.

worked great!

Followed the hookup guide and it worked perfect with my Arduino Uno! Very easy to use with a load cell.

It works just like any other HX711

I was comparing this to some of the others that I’ve picked up and really don’t see much in a difference for readings other than it is a bit more expensive. Its nice that they at least have dropped the price a little from when I bought it.

I do have to say the Sparkfun library is great as its probably the most comprehensive when setting up a load cell or tieing in 4 load sensors.

It took me a little researching on the differences between a load cell and a load sensor.

You can tie 1 load cell into the hx711 or you can tie 4 load sensors into this using a wheatstone bride.

Perfect for my sugar rocket motor test stand!

I knew Sparkfun was the place to go to get the components I needed for our experimental sugar rocket motor test stand with data logger. Now we can fine tune the Buder Rocket Boy’s sugar rocket engine formula this winter perfecting a replacement for commercial hobby rocket motors. The XH711 along with the 10kg straight bar load cell (TAL220) was a perfect fit. Precise, compact and at a great price. Thanks guys for designing and supplying awesome stuff!

Well done product

Well designed, works as advertised, documentation and SW is freely available. It took just few minutes to power it up and get good reading. I am very satisfied with this product.

Great board

Connection to cell are best done soldered directly to load cell. Awesome amplifier.

Good value and easy to follow guides for beginners like me

Had it up and publishing(Uno and Ethernet shield) to broker in 30 minutes.

easy to integrate with tutorials

This was my first time using load cells and did not know what to expect. I read the tutorials and got it wired up easily. I got it hooked up to my Arduino and with the library that Sparkfun provides I got it running with no fuss at all. The one problem I had was that the rate that it was updating was not very fast. After some reading I realized it has a jumper on the bottom which if you bridge will increase the data rate. Once I did that it worked perfectly for my application.

Still in the box!

I have not yet been able to work on my scales projects. I will update this review once I’ve completed the two projects.

Easy to use and accurate

This was surprisingly accurate. My load cell was for 780 g max. I calibrated it for 32 g, (two ½-13 nuts) weighted with a scale accurate to .001 g and then tested it up to 320 g. It was spot on.
The one problem I had was in finding the calibration constant. Mine was far different (much larger) than the example given in the tutorial, and the calibration program would have taken forever to slowly find it. I modified the program so it would take bigger steps and zero in on the constant faster.

Really helpful!

This really saved my partner and I for our project and the product got to my home faster than expected.

0 of 5 found this helpful:

4 weeks and I still don't have it.

FedEx sent my package all over the country. 4 weeks later I still don’t have it.

Good product, and remarkably tolerant of my stupidity

Very impressed. Through means of some heavy-duty stupidity on my part, I had to de-solder and re-solder some connections between the amps and the rest of my project multiple times. I thought sure I’d used too much heat and had destroyed the traces, but nope: both of my load cell amplifiers are still working flawlessly.

Easy to use amp

This is a great product and it’s really easy to install and use. I would definitely use it again.

Works great!

BEWARE! The HX711 is an analog-to-digital converter! It is not a simple amplifier! I went back and reread the product description and it’s not really obvious from reading the Sparkfun website. After I figured out how to get the data from the thing, everything went smoothly and the weighing systems appears to be accurate and repeatable.

Works great- see forum for device modifications for teensy

Hey, so as of Oct-2017, the Teensy 3.X core “shiftIn” function that is used by the default HX711 library is too fast. I opened a github issue, pjrc forum post, and sparkfun forum that all link together (as the three threads related to each other.) There’s a simple fix involving a delaymicro(1) in the library code

It’s up in the air as of october 2017 whether this is a HX711 library issue, or a teensy issue, insofar as teensy core is not emulating the slow AVR functionality, but at the same time, to add the delay to the core could disrupt code that relies on the teensy being faster with ShiftIn than the stock.

Anyway, after documenting my problem and getting community help on the fix, although it was a major hassle at first to use the HX711 breakout, it was an awesome demonstration of the community :). I hope it works well for you!

The actual results I’m getting from the HX711 are great. It’s superb to have a 24-bit device so easy to use and relatively cheap :)

Sparkfun should add some clarity on what the excitation voltage is for the HX711 breakout, and not assume everyone will want to calibrate their load cells and/or doesn’t have a datasheet for it. I was expected 4.2V from background reading on the HX711, but measured an excitation of 4.36V, and just a little bit of clarity on that core functionality might be useful. Maybe I didn’t see it in the guide, but the guide seemed to try and abstract what was going on with its calibration example, and may have been more educational if it got into excitation voltages.

Good Product and Great "Getting Started"

A super simple solution with a typically reliable SparkFun “Getting Started” guide! Using with the Sparkfun Redboard and a single 10kg load cell. The reason i shop with Sparkfun, is that I find their product guides understandable and complete. This is another example of a great guide and, of course, it was written by Nathan. I can quickly get started with the features of the project and world domination…

Used for robot paws!

I have a quadruped under construction, and each foot has a load cell to measure paw pressure to assist with balance calculations. I’m using non-SparkFun micro load cells, electrically similar to those SparkFun sells. I interface each HX711 to a 16-bit PIC and that has worked well. When the HX711 DAT signal goes low, indicating data available, it triggers an interrupt and all the CLK pulsing, and DAT reading, is handled by bit-banging in a loop in the interrupt service routine. It’s easy, responsive and low-overhead.

Measure Force

The HX711 amp made the connection simple and easy, and works great!

You can't beat this!

Easy to use, inexpensive, and very reliable. I love these.

Digital CG Scale

I use three HX711 to evaluate the CG of my RC planes. Works so far fine.

Nice load cell interface

I got this recently to go along with the wheatstone bridge combinator board so I could hack a bathroom scale to use as a load cell in a project. The HX711 made the signal from the strain gages readable with an Arduino. It all works pretty good!

Great ADC module

While meant for load cells, this is a great general purpose ADC module. I’ve used it across projects and embedded platforms for a better ADC than is typically included on chip. I love the serial communication model. Would be 5 stars if it didn’t have a maximum pulse width for the serial clock.

yet another sparkfun product that works great

works as expected, great hardware and components, libraries are well implemented yet again another reason why sparkfun staff is the goto for real life projects.

Works great!

He had no issues setting this up with our load cells and it works like a charm!

Good and simple!

Good and simple, easy to use!