ADC Count ↔ Voltage Converter
Counts to volts and back at any resolution and reference — including input voltage dividers, both directions.
Three catches: (1) “5 V” USB Vcc sits 4.6–5.1 V — if Vref is Vcc your calibration drifts with the cable; use the internal bandgap to measure Vcc. (2) High divider impedance starves the ADC's sample capacitor — keep source < 10 kΩ or add 100 nF at the pin. (3) ESP32's ADC is nonlinear near the rails; use its calibrated API, not the raw formula.
ADC Count to Voltage Converter computes ADC readings to volts and back, including input-divider scaling — free, instant and private in your browser. Arduino/ESP32 users turning analogRead numbers into real units use it to skip the datasheet algebra: type your numbers, read the answer with the substituted formula shown step by step, and share an exact permalink of the calculation.
About ADC Count ↔ Voltage Converter
ADC Count to Voltage Converter computes ADC readings to volts and back, including input-divider scaling using the standard engineering relation: V(pin) = count·Vref/2ⁿ; V(source) = V(pin)·(R1+R2)/R2. Worked live: count 512 on a 10-bit, 5 V Arduino is 2.50 V at the pin — 6.0 V at the source through a 1:2.4 divider. The result recalculates on every keystroke, the worked-example panel shows your numbers substituted into the formula, and the Copy permalink button encodes the inputs in the URL so a colleague opens exactly your calculation. Everything runs client-side — nothing you type leaves your device.
How to use ADC Count ↔ Voltage Converter
- 1Enter your values — the tool starts with realistic defaults for this exact use case, so the worked example is meaningful immediately.
- 2Read the live result and the worked-example panel, which substitutes your numbers into the formula step by step.
- 3Adjust any input to compare scenarios, then use Copy result or Copy permalink to share the calculation.
Why use ADC Count ↔ Voltage Converter?
- ✓Implements the real formula — V(pin) = count·Vref/2ⁿ — with the substitution shown, not a black box
- ✓Built for Arduino/ESP32 users turning analogRead numbers into real units
- ✓Copy result and permalink buttons — share the exact calculation in a README, forum answer or design review
- ✓100% free, no sign-up, runs entirely in your browser (works offline once loaded)
Frequently asked questions
How do you calculate adc count to voltage?+
ADC readings to volts and back, including input-divider scaling follows V(pin) = count·Vref/2ⁿ; V(source) = V(pin)·(R1+R2)/R2. For example, count 512 on a 10-bit, 5 V Arduino is 2.50 V at the pin — 6.0 V at the source through a 1:2.4 divider. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Why do my readings drift with USB power?+
Default Vref is Vcc, and 'USB 5 V' wanders 4.6–5.1 V with cable and load — your conversion factor wanders with it. Use the internal bandgap reference for absolute measurements, or measure Vcc itself against the bandgap and correct in software.
Why does a high-resistance divider read low and noisy?+
The ADC charges a small sample capacitor through your divider; above ~10 kΩ source impedance it can't settle in the sample window. Keep dividers stiff, add 100 nF at the pin (slow signals), lengthen sample time in the driver, or buffer with an op-amp.
Is the ADC Count to Voltage Converter free and private?+
Yes — completely free with no sign-up or usage limits, and it runs entirely in your browser: the values you enter are never uploaded or stored on a server.
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