Sensor Calculator

Convert ADC to Physical Units

How to use

Enter your microcontroller's ADC parameters and the sensor's physical range. This tool uses linear ratiometric scaling, which works for most standard analog sensors.

Raw ADC Value

The raw reading from your sensor

ADC Resolution (bits)

Determines the max ADC value

Reference Voltage (V)

e.g., 3.3V or 5.0V

Sensor Min Physical Value

Value at 0V or min ADC

Sensor Max Physical Value

Value at Vref or max ADC

Unit Name

The unit of measurement

Calculated Physical Value

0 °C

Enter values to analyze

Sensor Voltage

0.00 V

Max ADC Value

1023

Voltage Resolution

0.00 mV

Range Percentage

Detailed Sensor Analysis

Voltage Level

Analog signal strength

Reading Position

Where the reading falls in range

Precision

Smallest detectable change

Signal Health

Potential wiring or clipping issues

Electronics & Calibration Tips

Understanding ADC and Sensor Calculations

Microcontrollers read analog sensors using an Analog-to-Digital Converter (ADC). The ADC converts a continuous voltage into a discrete digital number. To make this number useful, we must scale it back to the physical unit the sensor measures (e.g., temperature, distance, pressure).

📐 Core Formulas

V_out = (ADC_raw / (2^n - 1)) × V_ref
Physical Value = Min_phys + ((ADC_raw / (2^n - 1)) × (Max_phys - Min_phys))

ADC_raw: The raw digital reading from the microcontroller.

n: ADC resolution in bits (e.g., 10 bits = max value 1023).

V_ref: The reference voltage of the ADC (e.g., 3.3V or 5.0V).

Min_phys / Max_phys: The sensor's minimum and maximum physical values.

🎯 Key Concepts Explained

Ratiometric Sensors: Most analog sensors are ratiometric, meaning their output voltage is proportional to the supply voltage. If V_ref changes, the calculation automatically compensates if configured correctly.
Resolution: The smallest change in voltage the ADC can detect. A 10-bit ADC at 5V has a resolution of ~4.88 mV per step. A 12-bit ADC at 3.3V has a resolution of ~0.8 mV per step.
Quantization Error: The inherent uncertainty in ADC readings, equal to ±½ of the voltage resolution. This is the theoretical limit of precision for your setup.
Linear vs. Non-Linear: This calculator assumes a linear relationship between voltage and the physical value. Sensors like thermistors (NTC/PTC) require the Steinhart-Hart equation or lookup tables instead of simple linear scaling.

💡 Best Practices for Sensor Accuracy

Use Oversampling: Take multiple rapid readings and average them to reduce random noise and effectively increase ADC resolution.
Add a Low-Pass Filter: A simple RC filter (resistor + capacitor) on the analog input pin smooths out high-frequency electrical noise.
Verify V_ref: Ensure your microcontroller's actual reference voltage matches the value used in the calculation. USB 5V can often fluctuate between 4.75V and 5.25V.
Calibrate at Two Points: For highest accuracy, measure the sensor's output at two known physical values and calculate the exact slope and offset, rather than relying on datasheet typicals.
Avoid Clipping: Ensure the sensor's maximum output voltage does not exceed the ADC's V_ref, or the reading will "clip" at the maximum ADC value.

🔍 How to Use This Tool

Enter the raw ADC value: The number your code reads from the analog pin.
Select ADC resolution: Choose the bit-depth of your microcontroller (e.g., Arduino Uno is 10-bit, ESP32 is 12-bit).
Set reference voltage: Enter the V_ref of your system (commonly 3.3V or 5.0V).
Define physical range: Input the minimum and maximum values the sensor can measure, along with the unit name.
Click "Calculate": Review the scaled physical value, voltage, and actionable calibration tips.