// Calibrating the load cell
#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_GFX.h>
#include "HX711.h"

// HX711 circuit wiring
const int LOADCELL_DOUT_PIN = 8;
const int LOADCELL_SCK_PIN = 9;

HX711 scale; //define scale

void setup() {
  Serial.begin(115200); //begin serial output

  scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN); //initialize scale
  tare(); //tare scale
 
}

void loop() {
  long reading = scale.get_units(10); //get scale reading
  display.print(reading); //display reading on OLED
  display.print("g");
 
}

void tare(){
  if (scale.is_ready()) {
    scale.set_scale();    
    Serial.println("Tare... remove any weights from the scale.");
    delay(5000);
    scale.tare();
    Serial.println("Tare done...");
    Serial.print("Place a known weight on the scale...");
    delay(5000);
    long reading = scale.get_units(10);
    Serial.print("Result: ");
    Serial.println(reading);
   
  }
   else {
    Serial.println("HX711 not found.");
  }
  delay(1000);
  }

//calibration factor will be the (reading)/(known weight)

Upload this code to for scale function. Remember to change the calibration factor in the code.
#include <Arduino.h>
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_GFX.h>
#include "HX711.h"

// HX711 circuit wiring
const int LOADCELL_DOUT_PIN = 8;
const int LOADCELL_SCK_PIN = 9;

HX711 scale; //define scale
#define CALIBRATION_FACTOR 21.3636363 //enter calibration factor from code 1
#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(OLED_RESET);

void setup() {
  Serial.begin(115200); //begin serial output
  display.begin(SSD1306_SWITCHCAPVCC,0x3C); //begin OLED display
  display.clearDisplay();
  scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN); //initialize scale
  scale.set_scale(CALIBRATION_FACTOR);   // calibrates the scale
  scale.tare();               // reset the scale to 0
 
}

void loop() {
 
  long reading = scale.get_units(10); // gets reading from the scale
  Serial.print("Result: ");
  Serial.println(reading);
  delay(1000);
  display.clearDisplay();
  display.setTextSize(4); // set OLED text size and color
  display.setTextColor(WHITE);
  display.setCursor(0,0); //location of reading on OLED
  display.print(reading); // display the current reading
  display.print("g");
  display.display();
  delay(1000);
}