diff --git a/homeassistant/components/apcupsd/sensor.py b/homeassistant/components/apcupsd/sensor.py
index 6989f58d3bb..1e73f040555 100644
--- a/homeassistant/components/apcupsd/sensor.py
+++ b/homeassistant/components/apcupsd/sensor.py
@@ -7,6 +7,7 @@ import voluptuous as vol
 from homeassistant.components.sensor import PLATFORM_SCHEMA
 from homeassistant.const import (
     CONF_RESOURCES,
+    FREQUENCY_HERTZ,
     POWER_WATT,
     TEMP_CELSIUS,
     TIME_MINUTES,
@@ -49,7 +50,7 @@ SENSOR_TYPES = {
     "itemp": ["Internal Temperature", TEMP_CELSIUS, "mdi:thermometer"],
     "lastxfer": ["Last Transfer", "", "mdi:transfer"],
     "linefail": ["Input Voltage Status", "", "mdi:information-outline"],
-    "linefreq": ["Line Frequency", "Hz", "mdi:information-outline"],
+    "linefreq": ["Line Frequency", FREQUENCY_HERTZ, "mdi:information-outline"],
     "linev": ["Input Voltage", UNIT_VOLT, "mdi:flash"],
     "loadpct": ["Load", UNIT_PERCENTAGE, "mdi:gauge"],
     "loadapnt": ["Load Apparent Power", UNIT_PERCENTAGE, "mdi:gauge"],
@@ -100,7 +101,7 @@ INFERRED_UNITS = {
     " Ampere": "A",
     " Volt-Ampere": "VA",
     " Watts": POWER_WATT,
-    " Hz": "Hz",
+    " Hz": FREQUENCY_HERTZ,
     " C": TEMP_CELSIUS,
     " Percent Load Capacity": UNIT_PERCENTAGE,
 }
diff --git a/homeassistant/components/cpuspeed/sensor.py b/homeassistant/components/cpuspeed/sensor.py
index 53598e24c70..4d984ed6829 100644
--- a/homeassistant/components/cpuspeed/sensor.py
+++ b/homeassistant/components/cpuspeed/sensor.py
@@ -5,7 +5,7 @@ from cpuinfo import cpuinfo
 import voluptuous as vol
 
 from homeassistant.components.sensor import PLATFORM_SCHEMA
-from homeassistant.const import CONF_NAME
+from homeassistant.const import CONF_NAME, FREQUENCY_GIGAHERTZ
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.entity import Entity
 
@@ -42,7 +42,6 @@ class CpuSpeedSensor(Entity):
         self._name = name
         self._state = None
         self.info = None
-        self._unit_of_measurement = "GHz"
 
     @property
     def name(self):
@@ -57,7 +56,7 @@ class CpuSpeedSensor(Entity):
     @property
     def unit_of_measurement(self):
         """Return the unit the value is expressed in."""
-        return self._unit_of_measurement
+        return FREQUENCY_GIGAHERTZ
 
     @property
     def device_state_attributes(self):
diff --git a/homeassistant/components/growatt_server/sensor.py b/homeassistant/components/growatt_server/sensor.py
index f51e38bd9da..d2b92e8efb3 100644
--- a/homeassistant/components/growatt_server/sensor.py
+++ b/homeassistant/components/growatt_server/sensor.py
@@ -13,6 +13,7 @@ from homeassistant.const import (
     CONF_PASSWORD,
     CONF_USERNAME,
     ENERGY_KILO_WATT_HOUR,
+    FREQUENCY_HERTZ,
     POWER_WATT,
     UNIT_VOLT,
 )
@@ -71,7 +72,7 @@ INVERTER_SENSOR_TYPES = {
     "inverter_internal_wattage": ("Internal wattage", POWER_WATT, "ppv", "power"),
     "inverter_reactive_voltage": ("Reactive voltage", UNIT_VOLT, "vacr", None),
     "inverter_inverter_reactive_amperage": ("Reactive amperage", "A", "iacr", None),
-    "inverter_frequency": ("AC frequency", "Hz", "fac", None),
+    "inverter_frequency": ("AC frequency", FREQUENCY_HERTZ, "fac", None),
     "inverter_current_wattage": ("Output power", POWER_WATT, "pac", "power"),
     "inverter_current_reactive_wattage": (
         "Reactive wattage",
diff --git a/homeassistant/components/homematic/sensor.py b/homeassistant/components/homematic/sensor.py
index 13e49bcf509..d52a4a2a19f 100644
--- a/homeassistant/components/homematic/sensor.py
+++ b/homeassistant/components/homematic/sensor.py
@@ -7,6 +7,7 @@ from homeassistant.const import (
     DEVICE_CLASS_POWER,
     DEVICE_CLASS_TEMPERATURE,
     ENERGY_WATT_HOUR,
+    FREQUENCY_HERTZ,
     POWER_WATT,
     SPEED_KILOMETERS_PER_HOUR,
     TEMP_CELSIUS,
@@ -58,7 +59,7 @@ HM_UNIT_HA_CAST = {
     "WIND_DIRECTION_RANGE": UNIT_DEGREE,
     "SUNSHINEDURATION": "#",
     "AIR_PRESSURE": "hPa",
-    "FREQUENCY": "Hz",
+    "FREQUENCY": FREQUENCY_HERTZ,
     "VALUE": "#",
 }
 
diff --git a/homeassistant/components/isy994/sensor.py b/homeassistant/components/isy994/sensor.py
index bc213d805ce..2e694e5d234 100644
--- a/homeassistant/components/isy994/sensor.py
+++ b/homeassistant/components/isy994/sensor.py
@@ -5,6 +5,7 @@ from typing import Callable
 from homeassistant.components.sensor import DOMAIN
 from homeassistant.const import (
     CONCENTRATION_PARTS_PER_MILLION,
+    FREQUENCY_HERTZ,
     LENGTH_CENTIMETERS,
     LENGTH_KILOMETERS,
     LENGTH_METERS,
@@ -110,7 +111,7 @@ UOM_FRIENDLY_NAME = {
     "87": "m³/m³",
     "88": "Water activity",
     "89": "RPM",
-    "90": "Hz",
+    "90": FREQUENCY_HERTZ,
     "91": f"{UNIT_DEGREE} (Relative to North)",
     "92": f"{UNIT_DEGREE} (Relative to South)",
 }
diff --git a/homeassistant/components/mysensors/sensor.py b/homeassistant/components/mysensors/sensor.py
index 3e9d39fa64b..ea621228cc4 100644
--- a/homeassistant/components/mysensors/sensor.py
+++ b/homeassistant/components/mysensors/sensor.py
@@ -3,6 +3,7 @@ from homeassistant.components import mysensors
 from homeassistant.components.sensor import DOMAIN
 from homeassistant.const import (
     ENERGY_KILO_WATT_HOUR,
+    FREQUENCY_HERTZ,
     LENGTH_METERS,
     MASS_KILOGRAMS,
     POWER_WATT,
@@ -36,7 +37,7 @@ SENSORS = {
     "V_VOLUME": ["m³", None],
     "V_LEVEL": {
         "S_SOUND": ["dB", "mdi:volume-high"],
-        "S_VIBRATION": ["Hz", None],
+        "S_VIBRATION": [FREQUENCY_HERTZ, None],
         "S_LIGHT_LEVEL": ["lx", "mdi:white-balance-sunny"],
     },
     "V_VOLTAGE": [UNIT_VOLT, "mdi:flash"],
diff --git a/homeassistant/components/nut/const.py b/homeassistant/components/nut/const.py
index b62a413e82b..13ffa318a4a 100644
--- a/homeassistant/components/nut/const.py
+++ b/homeassistant/components/nut/const.py
@@ -5,6 +5,7 @@ from homeassistant.components.sensor import (
     DEVICE_CLASS_TEMPERATURE,
 )
 from homeassistant.const import (
+    FREQUENCY_HERTZ,
     POWER_WATT,
     TEMP_CELSIUS,
     TIME_SECONDS,
@@ -159,10 +160,10 @@ SENSOR_TYPES = {
     ],
     "input.voltage": ["Input Voltage", UNIT_VOLT, "mdi:flash", None],
     "input.voltage.nominal": ["Nominal Input Voltage", UNIT_VOLT, "mdi:flash", None],
-    "input.frequency": ["Input Line Frequency", "hz", "mdi:flash", None],
+    "input.frequency": ["Input Line Frequency", FREQUENCY_HERTZ, "mdi:flash", None],
     "input.frequency.nominal": [
         "Nominal Input Line Frequency",
-        "hz",
+        FREQUENCY_HERTZ,
         "mdi:flash",
         None,
     ],
@@ -176,8 +177,13 @@ SENSOR_TYPES = {
     "output.current.nominal": ["Nominal Output Current", "A", "mdi:flash", None],
     "output.voltage": ["Output Voltage", UNIT_VOLT, "mdi:flash", None],
     "output.voltage.nominal": ["Nominal Output Voltage", UNIT_VOLT, "mdi:flash", None],
-    "output.frequency": ["Output Frequency", "hz", "mdi:flash", None],
-    "output.frequency.nominal": ["Nominal Output Frequency", "hz", "mdi:flash", None],
+    "output.frequency": ["Output Frequency", FREQUENCY_HERTZ, "mdi:flash", None],
+    "output.frequency.nominal": [
+        "Nominal Output Frequency",
+        FREQUENCY_HERTZ,
+        "mdi:flash",
+        None,
+    ],
 }
 
 STATE_TYPES = {
diff --git a/homeassistant/components/solaredge_local/sensor.py b/homeassistant/components/solaredge_local/sensor.py
index 8d1b7262fc0..d9e7a45def2 100644
--- a/homeassistant/components/solaredge_local/sensor.py
+++ b/homeassistant/components/solaredge_local/sensor.py
@@ -13,6 +13,7 @@ from homeassistant.const import (
     CONF_IP_ADDRESS,
     CONF_NAME,
     ENERGY_WATT_HOUR,
+    FREQUENCY_HERTZ,
     POWER_WATT,
     TEMP_CELSIUS,
     TEMP_FAHRENHEIT,
@@ -58,7 +59,7 @@ SENSOR_TYPES = {
     "current_frequency": [
         "gridfrequency",
         "Grid Frequency",
-        "Hz",
+        FREQUENCY_HERTZ,
         "mdi:current-ac",
         None,
     ],
diff --git a/homeassistant/const.py b/homeassistant/const.py
index 74647864fab..e2fc11cf22e 100644
--- a/homeassistant/const.py
+++ b/homeassistant/const.py
@@ -381,6 +381,10 @@ LENGTH_FEET: str = "ft"
 LENGTH_YARD: str = "yd"
 LENGTH_MILES: str = "mi"
 
+# Frequency units
+FREQUENCY_HERTZ = "Hz"
+FREQUENCY_GIGAHERTZ = f"G{FREQUENCY_HERTZ}"
+
 # Pressure units
 PRESSURE_PA: str = "Pa"
 PRESSURE_HPA: str = "hPa"