temp. no accurate with bylnk

hi all
i have a problem as my project temperature no accurate with blynk temperature display.(project temperature show 36 deg c but blynk show 32 deg C) is that my code no correct or need to improve?

int sens1; //sensor define
int swA = 12 ; //button input
int val; //val definitation
int tempPin =A0; //pin config
int sensorValue1 ; //initial gas sensor value
#include <Servo.h>
Servo myservo;

#define BLYNK_PRINT Serial //blynk print serial data

#include <ESP8266WiFi.h> //define ESP
#include <BlynkSimpleEsp8266.h> //define Blynk

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).

char auth =
//char auth =
// Your WiFi credentials.
// Set password to “” for open networks.
const char* ssid = “esp”;
const char* pass = “esp888”;

// Variable to store the previous state for Button 0.
char previousButton0 = 0;
Servo servo;


void setup()

// Set the pin as output.
pinMode(2, OUTPUT); // Set the pin as output.

Serial.begin(115200); //baudrate
Blynk.begin(auth, ssid, pass); //begin system Blynk
Blynk.virtualWrite(1,0); //set blynk virtual write
Blynk.virtualWrite(2,0); //set blynk virtual write
digitalWrite(2, HIGH); //off

void loop()
Blynk.run(); //runt he program
Blynk.virtualWrite(1,1023); //LED Blink High
Blynk.virtualWrite(1, 0); //LED Blink Low

val = analogRead(tempPin); //read temperature analog signal
float mv = ( val/1024.0)5000; //lm35 calculation
float cel = (mv/10)-20 ; //lm35 calculation
float farh = (cel
9)/5 + 32; //celcius calculation

Blynk.virtualWrite(2,cel); //LED Blink High

Serial.print(“TEMPRATURE = “); //print temp char in serial
Serial.print(cel); //print temp value in serial
Serial.print(”*C”); //print char c in serial
Serial.println(); //print new line