diff --git a/src/PMS/PMS5003.cpp b/src/PMS/PMS5003.cpp
index 128d1b1..268f9bb 100644
--- a/src/PMS/PMS5003.cpp
+++ b/src/PMS/PMS5003.cpp
@@ -1,5 +1,6 @@
 #include "PMS5003.h"
 #include "Arduino.h"
+#include "PMSUtils.h"
 
 #if defined(ESP8266)
 #include <SoftwareSerial.h>
@@ -63,7 +64,8 @@ bool PMS5003::begin(void) {
 
 #if defined(ESP8266)
   bsp->Pms5003.uart_tx_pin;
-  SoftwareSerial *uart = new SoftwareSerial(bsp->Pms5003.uart_tx_pin, bsp->Pms5003.uart_rx_pin);
+  SoftwareSerial *uart =
+      new SoftwareSerial(bsp->Pms5003.uart_tx_pin, bsp->Pms5003.uart_rx_pin);
   uart->begin(9600);
   if (pms.begin(uart) == false) {
     AgLog("PMS failed");
@@ -81,31 +83,6 @@ bool PMS5003::begin(void) {
   return true;
 }
 
-/**
- * @brief Convert PM2.5 to US AQI
- *
- * @param pm02
- * @return int
- */
-int PMS5003::pm25ToAQI(int pm02) {
-  if (pm02 <= 12.0)
-    return ((50 - 0) / (12.0 - .0) * (pm02 - .0) + 0);
-  else if (pm02 <= 35.4)
-    return ((100 - 50) / (35.4 - 12.0) * (pm02 - 12.0) + 50);
-  else if (pm02 <= 55.4)
-    return ((150 - 100) / (55.4 - 35.4) * (pm02 - 35.4) + 100);
-  else if (pm02 <= 150.4)
-    return ((200 - 150) / (150.4 - 55.4) * (pm02 - 55.4) + 150);
-  else if (pm02 <= 250.4)
-    return ((300 - 200) / (250.4 - 150.4) * (pm02 - 150.4) + 200);
-  else if (pm02 <= 350.4)
-    return ((400 - 300) / (350.4 - 250.4) * (pm02 - 250.4) + 300);
-  else if (pm02 <= 500.4)
-    return ((500 - 400) / (500.4 - 350.4) * (pm02 - 350.4) + 400);
-  else
-    return 500;
-}
-
 /**
  * @brief Read all package data then call to @ref getPMxxx to get the target
  * data
@@ -155,7 +132,7 @@ int PMS5003::getPm03ParticleCount(void) { return pmsData.PM_RAW_0_3; }
  * @param pm25 PM2.5 index
  * @return int PM2.5 US AQI
  */
-int PMS5003::convertPm25ToUsAqi(int pm25) { return this->pm25ToAQI(pm25); }
+int PMS5003::convertPm25ToUsAqi(int pm25) { return pm25ToAQI(pm25); }
 
 /**
  * @brief Check device initialized or not
diff --git a/src/PMS/PMS5003.h b/src/PMS/PMS5003.h
index 69e6de4..15b907c 100644
--- a/src/PMS/PMS5003.h
+++ b/src/PMS/PMS5003.h
@@ -2,8 +2,8 @@
 #define _AIR_GRADIENT_PMS5003_H_
 
 #include "../Main/BoardDef.h"
-#include "Stream.h"
 #include "PMS.h"
+#include "Stream.h"
 
 /**
  * @brief The class define how to handle PMS5003 sensor bas on @ref PMS class
@@ -41,6 +41,5 @@ private:
 
   bool begin(void);
   bool isBegin(void);
-  int pm25ToAQI(int pm02);
 };
 #endif /** _AIR_GRADIENT_PMS5003_H_ */
diff --git a/src/PMS/PMS5003T.cpp b/src/PMS/PMS5003T.cpp
index 57040a5..03b0fd2 100644
--- a/src/PMS/PMS5003T.cpp
+++ b/src/PMS/PMS5003T.cpp
@@ -1,5 +1,6 @@
 #include "PMS5003T.h"
 #include "Arduino.h"
+#include "PMSUtils.h"
 
 #if defined(ESP8266)
 #include <SoftwareSerial.h>
@@ -105,31 +106,6 @@ bool PMS5003T::begin(void) {
   return true;
 }
 
-/**
- * @brief Convert PM2.5 to US AQI
- *
- * @param pm02
- * @return int
- */
-int PMS5003T::pm25ToAQI(int pm02) {
-  if (pm02 <= 12.0)
-    return ((50 - 0) / (12.0 - .0) * (pm02 - .0) + 0);
-  else if (pm02 <= 35.4)
-    return ((100 - 50) / (35.4 - 12.0) * (pm02 - 12.0) + 50);
-  else if (pm02 <= 55.4)
-    return ((150 - 100) / (55.4 - 35.4) * (pm02 - 35.4) + 100);
-  else if (pm02 <= 150.4)
-    return ((200 - 150) / (150.4 - 55.4) * (pm02 - 55.4) + 150);
-  else if (pm02 <= 250.4)
-    return ((300 - 200) / (250.4 - 150.4) * (pm02 - 150.4) + 200);
-  else if (pm02 <= 350.4)
-    return ((400 - 300) / (350.4 - 250.4) * (pm02 - 250.4) + 300);
-  else if (pm02 <= 500.4)
-    return ((500 - 400) / (500.4 - 350.4) * (pm02 - 350.4) + 400);
-  else
-    return 500;
-}
-
 /**
  * @brief Read all package data then call to @ref getPMxxx to get the target
  * data
@@ -179,7 +155,7 @@ int PMS5003T::getPm03ParticleCount(void) { return pmsData.PM_RAW_0_3; }
  * @param pm25 PM2.5 index
  * @return int PM2.5 US AQI
  */
-int PMS5003T::convertPm25ToUsAqi(int pm25) { return this->pm25ToAQI(pm25); }
+int PMS5003T::convertPm25ToUsAqi(int pm25) { return pm25ToAQI(pm25); }
 
 /**
  * @brief Get temperature, Must call this method after @ref readData() success
diff --git a/src/PMS/PMS5003T.h b/src/PMS/PMS5003T.h
index a93cd40..ec4d78e 100644
--- a/src/PMS/PMS5003T.h
+++ b/src/PMS/PMS5003T.h
@@ -1,10 +1,10 @@
 #ifndef _PMS5003T_H_
 #define _PMS5003T_H_
 
-#include <HardwareSerial.h>
 #include "../Main/BoardDef.h"
 #include "PMS.h"
 #include "Stream.h"
+#include <HardwareSerial.h>
 
 /**
  * @brief The class define how to handle PMS5003T sensor bas on @ref PMS class
@@ -42,7 +42,6 @@ private:
 #endif
 
   bool begin(void);
-  int pm25ToAQI(int pm02);
   PMS pms;
   PMS::DATA pmsData;
   bool isBegin(void);
diff --git a/src/PMS/PMSUtils.cpp b/src/PMS/PMSUtils.cpp
new file mode 100644
index 0000000..f47813f
--- /dev/null
+++ b/src/PMS/PMSUtils.cpp
@@ -0,0 +1,26 @@
+#include "PMSUtils.h"
+
+/**
+ * @brief Convert PM2.5 to US AQI
+ *
+ * @param pm02
+ * @return int
+ */
+int pm25ToAQI(int pm02) {
+  if (pm02 <= 12.0)
+    return ((50 - 0) / (12.0 - .0) * (pm02 - .0) + 0);
+  else if (pm02 <= 35.4)
+    return ((100 - 50) / (35.4 - 12.0) * (pm02 - 12.0) + 50);
+  else if (pm02 <= 55.4)
+    return ((150 - 100) / (55.4 - 35.4) * (pm02 - 35.4) + 100);
+  else if (pm02 <= 150.4)
+    return ((200 - 150) / (150.4 - 55.4) * (pm02 - 55.4) + 150);
+  else if (pm02 <= 250.4)
+    return ((300 - 200) / (250.4 - 150.4) * (pm02 - 150.4) + 200);
+  else if (pm02 <= 350.4)
+    return ((400 - 300) / (350.4 - 250.4) * (pm02 - 250.4) + 300);
+  else if (pm02 <= 500.4)
+    return ((500 - 400) / (500.4 - 350.4) * (pm02 - 350.4) + 400);
+  else
+    return 500;
+}
diff --git a/src/PMS/PMSUtils.h b/src/PMS/PMSUtils.h
new file mode 100644
index 0000000..ffb5a84
--- /dev/null
+++ b/src/PMS/PMSUtils.h
@@ -0,0 +1,6 @@
+#ifndef _PMS_UTILS_H_
+#define _PMS_UTILS_H_
+
+int pm25ToAQI(int pm02);
+
+#endif /** _PMS_UTILS_H_ */