diff --git a/ecowitt2mqtt/data.py b/ecowitt2mqtt/data.py
index 0f8174cc..89678b7e 100644
--- a/ecowitt2mqtt/data.py
+++ b/ecowitt2mqtt/data.py
@@ -78,8 +78,8 @@
 )
 from ecowitt2mqtt.helpers.calculator.pollution import PollutantCalculator
 from ecowitt2mqtt.helpers.calculator.precipitation import (
-    RainRateCalculator,
-    RainVolumeCalculator,
+    AccumulatedPrecipitationCalculator,
+    PrecipitationRateCalculator,
 )
 from ecowitt2mqtt.helpers.calculator.pressure import PressureCalculator
 from ecowitt2mqtt.helpers.calculator.temperature import (
@@ -121,8 +121,8 @@
     DATA_POINT_GLOB_MOISTURE: RelativeHumidityCalculator,
     DATA_POINT_GLOB_PM10: PollutantCalculator,
     DATA_POINT_GLOB_PM25: PollutantCalculator,
-    DATA_POINT_GLOB_RAIN: RainVolumeCalculator,
-    DATA_POINT_GLOB_R_RAIN: RainRateCalculator,
+    DATA_POINT_GLOB_RAIN: AccumulatedPrecipitationCalculator,
+    DATA_POINT_GLOB_R_RAIN: PrecipitationRateCalculator,
     DATA_POINT_GLOB_TEMP: TemperatureCalculator,
     DATA_POINT_GLOB_TF: TemperatureCalculator,
     DATA_POINT_GLOB_VOLT: BatteryCalculator,
@@ -137,7 +137,7 @@
     DATA_POINT_LIGHTNING: LightningStrikeDistanceCalculator,
     DATA_POINT_LIGHTNING_NUM: LightningStrikeCountCalculator,
     DATA_POINT_LIGHTNING_TIME: EpochCalculator,
-    DATA_POINT_RAIN_RATE: RainRateCalculator,
+    DATA_POINT_RAIN_RATE: PrecipitationRateCalculator,
     DATA_POINT_RUNTIME: RuntimeCalculator,
     DATA_POINT_SAFE_EXPOSURE_TIME_SKIN_TYPE_1: SafeExposureCalculator,
     DATA_POINT_SAFE_EXPOSURE_TIME_SKIN_TYPE_2: SafeExposureCalculator,
diff --git a/ecowitt2mqtt/helpers/calculator/precipitation.py b/ecowitt2mqtt/helpers/calculator/precipitation.py
index 24d9fac3..8a324959 100644
--- a/ecowitt2mqtt/helpers/calculator/precipitation.py
+++ b/ecowitt2mqtt/helpers/calculator/precipitation.py
@@ -6,64 +6,58 @@
     PRECIPITATION_INCHES_PER_HOUR,
     PRECIPITATION_MILLIMETERS,
     PRECIPITATION_MILLIMETERS_PER_HOUR,
-    UNIT_SYSTEM_IMPERIAL,
 )
 from ecowitt2mqtt.helpers.calculator import CalculatedDataPoint, Calculator
 from ecowitt2mqtt.helpers.typing import PreCalculatedValueType
+from ecowitt2mqtt.util.unit_conversion import (
+    AccumulatedPrecipitationConverter,
+    PrecipitationRateConverter,
+)
 
 
-class RainRateCalculator(Calculator):
-    """Define a rain rate calculator."""
+class AccumulatedPrecipitationCalculator(Calculator):
+    """Define a rain volume calculator."""
+
+    DEFAULT_INPUT_UNIT = PRECIPITATION_INCHES
 
     @property
     def output_unit_imperial(self) -> str:
         """Get the default unit (imperial)."""
-        return PRECIPITATION_INCHES_PER_HOUR
+        return PRECIPITATION_INCHES
 
     @property
     def output_unit_metric(self) -> str:
         """Get the default unit (metric)."""
-        return PRECIPITATION_MILLIMETERS_PER_HOUR
+        return PRECIPITATION_MILLIMETERS
 
     def calculate_from_value(
         self, value: PreCalculatedValueType
     ) -> CalculatedDataPoint:
         """Perform the calculation."""
         assert isinstance(value, float)
+        converted_value = self.convert_value(AccumulatedPrecipitationConverter, value)
+        return self.get_calculated_data_point(converted_value)
 
-        if self._config.input_unit_system == self._config.output_unit_system:
-            rain_volume = value
-        elif self._config.output_unit_system == UNIT_SYSTEM_IMPERIAL:
-            rain_volume = round(value / 25.4, 1)
-        else:
-            rain_volume = round(value * 25.4, 1)
-        return self.get_calculated_data_point(rain_volume)
 
+class PrecipitationRateCalculator(Calculator):
+    """Define a rain rate calculator."""
 
-class RainVolumeCalculator(Calculator):
-    """Define a rain volume calculator."""
+    DEFAULT_INPUT_UNIT = PRECIPITATION_INCHES_PER_HOUR
 
     @property
     def output_unit_imperial(self) -> str:
         """Get the default unit (imperial)."""
-        return PRECIPITATION_INCHES
+        return PRECIPITATION_INCHES_PER_HOUR
 
     @property
     def output_unit_metric(self) -> str:
         """Get the default unit (metric)."""
-        return PRECIPITATION_MILLIMETERS
+        return PRECIPITATION_MILLIMETERS_PER_HOUR
 
     def calculate_from_value(
         self, value: PreCalculatedValueType
     ) -> CalculatedDataPoint:
         """Perform the calculation."""
         assert isinstance(value, float)
-
-        if self._config.input_unit_system == self._config.output_unit_system:
-            final_value = value
-        elif self._config.output_unit_system == UNIT_SYSTEM_IMPERIAL:
-            final_value = round(value / 25.4, 1)
-        else:
-            final_value = round(value * 25.4, 1)
-
-        return self.get_calculated_data_point(final_value)
+        converted_value = self.convert_value(PrecipitationRateConverter, value)
+        return self.get_calculated_data_point(converted_value)
diff --git a/tests/test_data.py b/tests/test_data.py
index 54618528..2f2786ad 100644
--- a/tests/test_data.py
+++ b/tests/test_data.py
@@ -5202,14 +5202,14 @@ def test_unit_conversion_to_imperial(device_data, ecowitt):
         ),
         "monthlyrain": CalculatedDataPoint(
             "rain",
-            2.2,
+            55.3,
             unit=PRECIPITATION_INCHES,
             attributes={},
             data_type=DataPointType.NON_BOOLEAN,
         ),
         "yearlyrain": CalculatedDataPoint(
             "rain",
-            4.4,
+            112.8,
             unit=PRECIPITATION_INCHES,
             attributes={},
             data_type=DataPointType.NON_BOOLEAN,
@@ -5573,14 +5573,14 @@ def test_unit_conversion_to_imperial(device_data, ecowitt):
                 ),
                 "monthlyrain": CalculatedDataPoint(
                     "rain",
-                    55.3,
+                    55.2958,
                     unit=PRECIPITATION_MILLIMETERS,
                     attributes={},
                     data_type=DataPointType.NON_BOOLEAN,
                 ),
                 "yearlyrain": CalculatedDataPoint(
                     "rain",
-                    112.8,
+                    112.8014,
                     unit=PRECIPITATION_MILLIMETERS,
                     attributes={},
                     data_type=DataPointType.NON_BOOLEAN,
@@ -5893,14 +5893,14 @@ def test_unit_conversion_to_imperial(device_data, ecowitt):
                 ),
                 "yearlyrain": CalculatedDataPoint(
                     "rain",
-                    298.6,
+                    298.6024,
                     unit=PRECIPITATION_MILLIMETERS,
                     attributes={},
                     data_type=DataPointType.NON_BOOLEAN,
                 ),
                 "totalrain": CalculatedDataPoint(
                     "rain",
-                    298.6,
+                    298.6024,
                     unit=PRECIPITATION_MILLIMETERS,
                     attributes={},
                     data_type=DataPointType.NON_BOOLEAN,