diff --git a/Marlin/src/HAL/ESP32/HAL.cpp b/Marlin/src/HAL/ESP32/HAL.cpp
index 4000dcc908..c1a44a3dea 100644
--- a/Marlin/src/HAL/ESP32/HAL.cpp
+++ b/Marlin/src/HAL/ESP32/HAL.cpp
@@ -229,11 +229,15 @@ void MarlinHAL::adc_init() {
   }
 }
 
+#ifndef ADC_REFERENCE_VOLTAGE
+  #define ADC_REFERENCE_VOLTAGE 3.3
+#endif
+
 void MarlinHAL::adc_start(const pin_t pin) {
   const adc1_channel_t chan = get_channel(pin);
   uint32_t mv;
   esp_adc_cal_get_voltage((adc_channel_t)chan, &characteristics[attenuations[chan]], &mv);
-  adc_result = mv * 1023.0 / 3300.0;
+  adc_result = mv * 1023.0f / float(ADC_REFERENCE_VOLTAGE) / 1000.0f;
 
   // Change the attenuation level based on the new reading
   adc_atten_t atten;
diff --git a/Marlin/src/pins/esp32/pins_MKS_TINYBEE.h b/Marlin/src/pins/esp32/pins_MKS_TINYBEE.h
index 122dad2146..68b8ed4ac8 100644
--- a/Marlin/src/pins/esp32/pins_MKS_TINYBEE.h
+++ b/Marlin/src/pins/esp32/pins_MKS_TINYBEE.h
@@ -113,6 +113,11 @@
 //#define E0_AUTO_FAN_PIN                    148  // need to update Configuration_adv.h @section extruder
 //#define E1_AUTO_FAN_PIN                    149  // need to update Configuration_adv.h @section extruder
 
+//
+// ADC Reference Voltage
+//
+#define ADC_REFERENCE_VOLTAGE                2.5  // 2.5V reference VDDA
+
 //
 // MicroSD card
 //