The map() Function

What is map()?

map() re-scales a number from one range to another. It's one of the most useful Arduino functions.

long map(long value, long fromLow, long fromHigh, long toLow, long toHigh)

How It Works

map(value, fromLow, fromHigh, toLow, toHigh)

Translates value from the range [fromLow, fromHigh] to [toLow, toHigh].

Common Examples

Potentiometer → Servo angle

int potValue = analogRead(A0);           // 0-1023
int angle = map(potValue, 0, 1023, 0, 180); // 0-180

Potentiometer → LED brightness

int potValue = analogRead(A0);              // 0-1023
int brightness = map(potValue, 0, 1023, 0, 255); // 0-255

Sensor → Display percentage

int raw = analogRead(A0);                    // 0-1023
int percent = map(raw, 0, 1023, 0, 100);    // 0-100

Inverted mapping

// Reverse: more light = lower value
int brightness = map(lightLevel, 0, 1023, 255, 0);

Important Notes

• map() uses integer math, so no decimal results
• Values outside the input range get extrapolated (not clamped)
• Use constrain() if you need to clamp the result:

int value = constrain(map(raw, 200, 800, 0, 255), 0, 255);