int analogInput = 0; float vout = 0.0; float vin = 0.0; float val = 0.0; float R1 = 100000.0; // resistance of R1 (100K) float R2 = 10000.0; // resistance of R2 (10K) int value = 0; void setup() { Serial.begin(9600); pinMode(analogInput, INPUT); } void loop() { value = analogRead(analogInput); vout = (value * 5) / 1024.0; vin = vout / (R2 / (R1 + R2)); val = vin*8; if (vin < 0.09) { val = 0.0; } Serial.println(val); }