diff --git a/libraries/AP_Compass/AP_Compass_AK8963.cpp b/libraries/AP_Compass/AP_Compass_AK8963.cpp
index f9598b80ea..3c1edd31c6 100644
--- a/libraries/AP_Compass/AP_Compass_AK8963.cpp
+++ b/libraries/AP_Compass/AP_Compass_AK8963.cpp
@@ -180,8 +180,6 @@ bool AP_Compass_AK8963::init()
     set_dev_id(_compass_instance, _bus->get_dev_id());
     hal.scheduler->register_timer_process(FUNCTOR_BIND_MEMBER(&AP_Compass_AK8963::_update, void));
 
-    set_milligauss_ratio(_compass_instance, 1.0f);
-    
     _bus_sem->give();
     hal.scheduler->resume_timer_procs();
 
diff --git a/libraries/AP_Compass/AP_Compass_Backend.cpp b/libraries/AP_Compass/AP_Compass_Backend.cpp
index 1bfc1642bd..4aa694ab26 100644
--- a/libraries/AP_Compass/AP_Compass_Backend.cpp
+++ b/libraries/AP_Compass/AP_Compass_Backend.cpp
@@ -141,9 +141,3 @@ void AP_Compass_Backend::set_external(uint8_t instance, bool external)
 {
     _compass._state[instance].external.set(external);
 }
-
-// set ratio to convert to milligauss
-void AP_Compass_Backend::set_milligauss_ratio(uint8_t instance, float ratio)
-{
-    _compass._state[instance].milligauss_ratio = ratio;
-}
diff --git a/libraries/AP_Compass/AP_Compass_Backend.h b/libraries/AP_Compass/AP_Compass_Backend.h
index 1d6ae29a3e..6d41721857 100644
--- a/libraries/AP_Compass/AP_Compass_Backend.h
+++ b/libraries/AP_Compass/AP_Compass_Backend.h
@@ -73,9 +73,6 @@ protected:
     // set external state for an instance
     void set_external(uint8_t instance, bool external);
 
-    // set ratio to convert to milligauss
-    void set_milligauss_ratio(uint8_t instance, float ratio);
-    
     // access to frontend
     Compass &_compass;
 
diff --git a/libraries/AP_Compass/AP_Compass_HIL.cpp b/libraries/AP_Compass/AP_Compass_HIL.cpp
index afc2b07dc7..671fcf2b56 100644
--- a/libraries/AP_Compass/AP_Compass_HIL.cpp
+++ b/libraries/AP_Compass/AP_Compass_HIL.cpp
@@ -53,7 +53,6 @@ AP_Compass_HIL::init(void)
     // register two compass instances
     for (uint8_t i=0; i<HIL_NUM_COMPASSES; i++) {
         _compass_instance[i] = register_compass();
-        set_milligauss_ratio(_compass_instance[i], 1.0f);
     }
     return true;
 }
diff --git a/libraries/AP_Compass/AP_Compass_HMC5843.cpp b/libraries/AP_Compass/AP_Compass_HMC5843.cpp
index 951485d967..5dbe6c6943 100644
--- a/libraries/AP_Compass/AP_Compass_HMC5843.cpp
+++ b/libraries/AP_Compass/AP_Compass_HMC5843.cpp
@@ -332,8 +332,6 @@ AP_Compass_HMC5843::init()
     _compass_instance = register_compass();
     set_dev_id(_compass_instance, _product_id);
 
-    set_milligauss_ratio(_compass_instance, 1.0f);
-
 #if CONFIG_HAL_BOARD == HAL_BOARD_LINUX && CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_RASPILOT
     set_external(_compass_instance, true);
 #endif
diff --git a/libraries/AP_Compass/AP_Compass_LSM303D.cpp b/libraries/AP_Compass/AP_Compass_LSM303D.cpp
index f2b91a74fe..5bf2643304 100644
--- a/libraries/AP_Compass/AP_Compass_LSM303D.cpp
+++ b/libraries/AP_Compass/AP_Compass_LSM303D.cpp
@@ -341,8 +341,6 @@ AP_Compass_LSM303D::init()
 
     hal.scheduler->register_timer_process(FUNCTOR_BIND_MEMBER(&AP_Compass_LSM303D::_update, void));
 
-    set_milligauss_ratio(_compass_instance, 1.0f);
-
     _spi_sem->give();
     hal.scheduler->resume_timer_procs();
     _initialised = true;
diff --git a/libraries/AP_Compass/AP_Compass_PX4.cpp b/libraries/AP_Compass/AP_Compass_PX4.cpp
index d1f1048e85..8f5a41cbd4 100644
--- a/libraries/AP_Compass/AP_Compass_PX4.cpp
+++ b/libraries/AP_Compass/AP_Compass_PX4.cpp
@@ -96,7 +96,6 @@ bool AP_Compass_PX4::init(void)
         _count[i] = 0;
         _sum[i].zero();
 
-        set_milligauss_ratio(_instance[i], 1.0f);
     }
 
     // give the driver a chance to run, and gather one sample
diff --git a/libraries/AP_Compass/Compass.h b/libraries/AP_Compass/Compass.h
index 370d98eb59..596fee568d 100644
--- a/libraries/AP_Compass/Compass.h
+++ b/libraries/AP_Compass/Compass.h
@@ -119,7 +119,7 @@ public:
     uint8_t get_count(void) const { return _compass_count; }
 
     /// Return the current field as a Vector3f
-    const Vector3f &get_field(uint8_t i) const { return _state[i].field * _state[i].milligauss_ratio; }
+    const Vector3f &get_field(uint8_t i) const { return _state[i].field; }
     const Vector3f &get_field(void) const { return get_field(get_primary()); }
 
     // raw/unfiltered measurement interface
@@ -180,7 +180,7 @@ public:
     ///
     /// @returns                    The current compass offsets.
     ///
-    const Vector3f &get_offsets(uint8_t i) const { return _state[i].offset * _state[i].milligauss_ratio; }
+    const Vector3f &get_offsets(uint8_t i) const { return _state[i].offset; }
     const Vector3f &get_offsets(void) const { return get_offsets(get_primary()); }
 
     /// Sets the initial location used to get declination
@@ -391,7 +391,6 @@ private:
 
         // corrected magnetic field strength
         Vector3f    field;
-        float       milligauss_ratio;
 
         // when we last got data
         uint32_t    last_update_ms;