diff --git a/include/interfaces/iDistance.hpp b/include/interfaces/iDistance.hpp
index 89bd7300..5356af1a 100644
--- a/include/interfaces/iDistance.hpp
+++ b/include/interfaces/iDistance.hpp
@@ -40,7 +40,7 @@ namespace upm
     /**
      * Get distance from sensor
      * 
-     * @return Returns the distance
+     * @return Returns the distance in cm
      */
     virtual float getDistance() = 0;
     /**
diff --git a/include/interfaces/iDistanceInterrupter.hpp b/include/interfaces/iDistanceInterrupter.hpp
index 9a991539..22b5238e 100644
--- a/include/interfaces/iDistanceInterrupter.hpp
+++ b/include/interfaces/iDistanceInterrupter.hpp
@@ -33,6 +33,12 @@ namespace upm
   {
   public:
     virtual ~iDistanceInterrupter() {}
+
+    /**
+     * Determines if objected is detected
+     * 
+     * @return True if the sensor has detected an object
+     */
     virtual bool objectDetected() = 0;
   };
 }
diff --git a/include/interfaces/iHeartRate.hpp b/include/interfaces/iHeartRate.hpp
index 2ecaec8e..6aea6b99 100644
--- a/include/interfaces/iHeartRate.hpp
+++ b/include/interfaces/iHeartRate.hpp
@@ -37,7 +37,7 @@ namespace upm
     /**
      * Retrieve the computed heart rate
      *
-     * @return Computed heart rate
+     * @return Computed heart rate in BPM (beats per minute)
      */
     virtual int getHeartRate() = 0;
   };
diff --git a/include/interfaces/iHumidity.hpp b/include/interfaces/iHumidity.hpp
index da03113e..2afa9748 100644
--- a/include/interfaces/iHumidity.hpp
+++ b/include/interfaces/iHumidity.hpp
@@ -37,7 +37,7 @@ namespace upm
     /**
      * Measures humidity around the sensor
      * 
-     * @return Gets the humidity value
+     * @return Gets the relativ humidity value (%)
      */
     virtual float getHumidity() = 0;
   };
diff --git a/include/interfaces/iLight.hpp b/include/interfaces/iLight.hpp
index 94524b59..090f7f55 100644
--- a/include/interfaces/iLight.hpp
+++ b/include/interfaces/iLight.hpp
@@ -37,7 +37,7 @@ namespace upm
         /**
          * Get luminance
          * 
-         * @return Luminance value
+         * @return Luminance value in lux
          */
         virtual float getLuminance() = 0;
     };
diff --git a/include/interfaces/iTemperature.hpp b/include/interfaces/iTemperature.hpp
index 4001b575..9a8ba2a8 100644
--- a/include/interfaces/iTemperature.hpp
+++ b/include/interfaces/iTemperature.hpp
@@ -42,7 +42,7 @@ namespace upm
     /**
      * Measures temperature
      * 
-     * @return temperature value
+     * @return temperature value in degrees Celsius
      */
     virtual float getTemperature() = 0;
 
diff --git a/src/maxsonarez/maxsonarez.hpp b/src/maxsonarez/maxsonarez.hpp
index 65464d09..6b970b9f 100644
--- a/src/maxsonarez/maxsonarez.hpp
+++ b/src/maxsonarez/maxsonarez.hpp
@@ -92,9 +92,9 @@ namespace upm {
     int inches();
 
     /**
-     * Gets the distance to the object in inches
+     * Gets the distance to the object in cm
      *
-     * @return Distance to the object in inches
+     * @return Distance to the object in cm
      */
     virtual float getDistance();