---
title: "MQTT Sensor"
description: "Instructions on how to integrate MQTT sensors within Home Assistant."
ha_category:
  - Sensor
ha_release: 0.7
ha_iot_class: Configurable
ha_domain: mqtt
---

This `mqtt` sensor platform uses the MQTT message payload as the sensor value. If messages in this `state_topic` are published with *RETAIN* flag, the sensor will receive an instant update with last known value. Otherwise, the initial state will be undefined.

## Configuration


To use an MQTT sensor in your installation, [add a MQTT device as a subentry](/integrations/mqtt/#configuration), or add the following to your {% term "`configuration.yaml`" %} file.
{% include integrations/restart_ha_after_config_inclusion.md %}

```yaml
# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Bedroom Temperature"
      state_topic: "home/bedroom/temperature"
```

Alternatively, a more advanced approach is to set it up via [MQTT discovery](/integrations/mqtt/#mqtt-discovery).

{% configuration %}
availability:
  description: A list of MQTT topics subscribed to receive availability (online/offline) updates. Must not be used together with `availability_topic`.
  required: false
  type: list
  keys:
    payload_available:
      description: The payload that represents the available state.
      required: false
      type: string
      default: online
    payload_not_available:
      description: The payload that represents the unavailable state.
      required: false
      type: string
      default: offline
    topic:
      description: An MQTT topic subscribed to receive availability (online/offline) updates.
      required: true
      type: string
    value_template:
      description: "Defines a [template](/docs/configuration/templating/#using-value-templates-with-mqtt) to extract device's availability from the `topic`. To determine the devices's availability result of this template will be compared to `payload_available` and `payload_not_available`."
      required: false
      type: template
availability_mode:
  description: When `availability` is configured, this controls the conditions needed to set the entity to `available`. Valid entries are `all`, `any`, and `latest`. If set to `all`, `payload_available` must be received on all configured availability topics before the entity is marked as online. If set to `any`, `payload_available` must be received on at least one configured availability topic before the entity is marked as online. If set to `latest`, the last `payload_available` or `payload_not_available` received on any configured availability topic controls the availability.
  required: false
  type: string
  default: latest
availability_template:
  description: "Defines a [template](/docs/configuration/templating/#using-value-templates-with-mqtt) to extract device's availability from the `availability_topic`. To determine the devices's availability result of this template will be compared to `payload_available` and `payload_not_available`."
  required: false
  type: template
availability_topic:
  description: The MQTT topic subscribed to receive availability (online/offline) updates.
  required: false
  type: string
default_entity_id:
  description: Use `default_entity_id` instead of name for automatic generation of the entity ID. For example, `sensor.foobar`. When used without a `unique_id`, the entity ID will update during restart or reload if the entity ID is available.  If the entity ID already exists, the entity ID will be created with a number at the end. When used with a `unique_id`, the `default_entity_id` is only used when the entity is added for the first time. When set, this overrides a user-customized entity ID if the entity was deleted and added again.
  required: false
  type: string
device:
  description: "Information about the device this sensor is a part of to tie it into the [device registry](https://developers.home-assistant.io/docs/device_registry_index/). Only works when [`unique_id`](#unique_id) is set. At least one of identifiers or connections must be present to identify the device."
  required: false
  type: map
  keys:
    configuration_url:
      description: 'A link to the webpage that can manage the configuration of this device. Can be either an `http://`, `https://` or an internal `homeassistant://` URL.'
      required: false
      type: string
    connections:
      description: 'A list of connections of the device to the outside world as a list of tuples `[connection_type, connection_identifier]`. For example the MAC address of a network interface: `"connections": [["mac", "02:5b:26:a8:dc:12"]]`.'
      required: false
      type: list
    hw_version:
      description: The hardware version of the device.
      required: false
      type: string
    identifiers:
      description: A list of IDs that uniquely identify the device. For example a serial number.
      required: false
      type: [string, list]
    manufacturer:
      description: The manufacturer of the device.
      required: false
      type: string
    model:
      description: The model of the device.
      required: false
      type: string
    model_id:
      description: The model identifier of the device.
      required: false
      type: string
    name:
      description: The name of the device.
      required: false
      type: string
    serial_number:
      description: "The serial number of the device."
      required: false
      type: string
    suggested_area:
      description: 'Suggest an area if the device isn’t in one yet.'
      required: false
      type: string
    sw_version:
      description: The firmware version of the device.
      required: false
      type: string
    via_device:
      description: 'Identifier of a device that routes messages between this device and Home Assistant. Examples of such devices are hubs, or parent devices of a sub-device. This is used to show device topology in Home Assistant.'
      required: false
      type: string
device_class:
  description: The [type/class](/integrations/sensor/#device-class) of the sensor to set the icon in the frontend. The `device_class` can be `null`.
  required: false
  type: device_class
enabled_by_default:
  description: Flag which defines if the entity should be enabled when first added.
  required: false
  type: boolean
  default: true
encoding:
  description: The encoding of the payloads received. Set to `""` to disable decoding of incoming payload.
  required: false
  type: string
  default: "utf-8"
entity_category:
  description: The [category](https://developers.home-assistant.io/docs/core/entity#generic-properties) of the entity. When set, the entity category must be `diagnostic` for sensors.
  required: false
  type: string
entity_picture:
  description: "Picture URL for the entity."
  required: false
  type: string
expire_after:
  description: If set, it defines the number of seconds after the sensor's state expires if it's not updated. After expiry, the sensor's state becomes `unavailable`. Default the sensors state never expires. By default, the sensor's state never expires. Note that when a sensor's value was sent retained to the MQTT broker, the last value sent will be replayed by the MQTT broker when Home Assistant restarts or is reloaded. As this could cause the sensor to become available with an expired state, it is not recommended to retain the sensor's state payload at the MQTT broker. Home Assistant will store and restore the sensor's state for you and calculate the remaining time to retain the sensor's state before it becomes unavailable.
  required: false
  type: integer
  default: 0
force_update:
  description: Sends update events even if the value hasn't changed. Useful if you want to have meaningful value graphs in history.
  required: false
  type: boolean
  default: false
icon:
  description: "[Icon](/docs/configuration/customizing-devices/#icon) for the entity."
  required: false
  type: icon
json_attributes_template:
  description: "Defines a [template](/docs/configuration/templating/#using-value-templates-with-mqtt) to extract the JSON dictionary from messages received on the `json_attributes_topic`."
  required: false
  type: template
json_attributes_topic:
  description: The MQTT topic subscribed to receive a JSON dictionary payload and then set as sensor attributes. Implies `force_update` of the current sensor state when a message is received on this topic.
  required: false
  type: string
last_reset_value_template:
  description: "Defines a [template](/docs/configuration/templating/#using-value-templates-with-mqtt) to extract the last_reset. When `last_reset_value_template` is set, the `state_class` option must be `total`. Available variables: `entity_id`. The `entity_id` can be used to reference the entity's attributes."
  required: false
  type: template
name:
  description: The name of the MQTT sensor. Can be set to `null` if only the device name is relevant.
  required: false
  type: string
  default: MQTT Sensor
options:
  description: List of allowed sensor state value. An empty list is not allowed. The sensor's `device_class` must be set to `enum`. The `options` option cannot be used together with `state_class` or `unit_of_measurement`.
  required: false
  type: list
payload_available:
  description: The payload that represents the available state.
  required: false
  type: string
  default: online
payload_not_available:
  description: The payload that represents the unavailable state.
  required: false
  type: string
  default: offline
platform:
  description: Must be `sensor`. Only allowed and required in [MQTT auto discovery device messages](/integrations/mqtt/#device-discovery-payload).
  required: true
  type: string
suggested_display_precision:
  description: The number of decimals which should be used in the sensor's state after rounding.
  required: false
  type: integer
qos:
  description: The maximum QoS level to be used when receiving and publishing messages.
  required: false
  type: integer
  default: 0
state_class:
  description: The [state_class](https://developers.home-assistant.io/docs/core/entity/sensor#available-state-classes) of the sensor.
  required: false
  type: string
state_topic:
  description: The MQTT topic subscribed to receive sensor values. If `device_class`, `state_class`, `unit_of_measurement` or `suggested_display_precision` is set, and a numeric value is expected, an empty value `''` will be ignored and will not update the state, a `'None'` value will set the sensor to an `unknown` state. If a `value_template` is used to parse a JSON payload, a `null` value in the JSON [will be rendered as](/docs/configuration/templating/#using-value-templates-with-mqtt) `'None'`. Note that the `device_class` can be `null`.
  required: true
  type: string
unique_id:
  description: "An ID that uniquely identifies this sensor. If two sensors have the same unique ID, Home Assistant will raise an exception. Required when used with device-based discovery."
  required: false
  type: string
unit_of_measurement:
  description: Defines the units of measurement of the sensor, if any. The `unit_of_measurement` can be `null`.
  required: false
  type: string
value_template:
  description: "Defines a [template](/docs/configuration/templating/#using-value-templates-with-mqtt) to extract the value. If the template throws an error, the current state will be used instead."
  required: false
  type: template
{% endconfiguration %}

## Examples

In this section, you find some real-life examples showing how to use this sensor.

### Processing Unix EPOCH timestamps

The example below shows how an MQTT sensor can process a Unix EPOCH payload.

{% raw %}

Set up via YAML:

```yaml
# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "turned on"
      state_topic: "pump/timestamp_on"
      device_class: "timestamp"
      value_template: "{{ as_datetime(value) }}"
      unique_id: "hp_1231232_ts_on"
      device:
        name: "Heat pump"
        identifiers:
          - "hp_1231232"
```

{% endraw %}

Or set up via MQTT discovery:

Discovery topic: `homeassistant/sensor/hp_1231232/config`

{% raw %}

```json
{
  "name": "turned on",
  "state_topic": "pump/timestamp_on",
  "device_class": "timestamp",
  "value_template": "{{ as_datetime(value) }}",
  "unique_id": "hp_1231232_ts_on",
  "device": {
    "name": "Heat pump",
    "identifiers": [
      "hp_1231232"
    ]
  }
}
```

{% endraw %}

To test, you can use the command line tool `mosquitto_pub` shipped with `mosquitto` or the `mosquitto-clients` package to send MQTT messages.

Payload topic: `pump/timestamp_on`
Payload: `1707294116`

To set the state of the sensor manually:

```bash
mosquitto_pub -h 127.0.0.1 -p 1883 -u username -P some_password -t pump/timestamp_on -m '1707294116'
```

Make sure the IP address of your MQTT broker is used and that user credentials have been set up correctly.

The `value_template` will render the Unix EPOCH timestamp to correct format: `2024-02-07 08:21:56+00:00`.

### JSON attributes topic configuration

The example sensor below shows a configuration example which uses the following separate topic and JSON structure to add extra attributes.

Topic: `home/sensor1/attributes`
 ```json
 {
    "ClientName": <string>,
    "IP": <string>,
    "MAC": <string>,
    "RSSI": <string>,
    "HostName": <string>,
    "ConnectedSSID": <string>
}
 ```
 It also makes use of the `availability` topic.

Extra attributes will be displayed in the frontend and can also be extracted in [Templates](/docs/configuration/templating/#attributes). For example, to extract the `ClientName` attribute from the sensor below, use a template similar to: {% raw %}`{{ state_attr('sensor.bs_rssi', 'ClientName') }}`{% endraw %}.

{% raw %}

```yaml
# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "RSSI"
      state_topic: "home/sensor1/infojson"
      unit_of_measurement: "dBm"
      value_template: "{{ value_json.RSSI }}"
      availability:
        - topic: "home/sensor1/status"
      payload_available: "online"
      payload_not_available: "offline"
      json_attributes_topic: "home/sensor1/attributes"
```

{% endraw %}

### JSON attributes template configuration

The example sensor below shows a configuration example which uses the following topic and JSON structure with a template to add `Timer1.Arm` and `Timer1.Time` as extra attributes.

Topic: `tele/sonoff/sensor`
```json
{
    "Timer1": {
        "Arm": <status>,
        "Time": <time>
    },
    "Timer2": {
        "Arm": <status>,
        "Time": <time>
    }
}
``` 
To instead only add `Timer1.Arm`as an extra attribute, change `json_attributes_template` to: {% raw %}`"{{ {'Arm': value_json.Timer1} | tojson }}"`{% endraw %}.

Extra attributes will be displayed in the frontend and can also be extracted in [Templates](/docs/configuration/templating/#attributes). For example, to extract the `Arm` attribute from the sensor below, use a template similar to: {% raw %}`{{ state_attr('sensor.timer1', 'Arm') }}`{% endraw %}.

{% raw %}

```yaml
# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Timer 1"
      state_topic: "tele/sonoff/sensor"
      value_template: "{{ value_json.Timer1.Arm }}"
      json_attributes_topic: "tele/sonoff/sensor"
      json_attributes_template: "{{ value_json.Timer1 | tojson }}"

    - name: "Timer 2"
      state_topic: "tele/sonoff/sensor"
      value_template: "{{ value_json.Timer2.Arm }}"
      json_attributes_topic: "tele/sonoff/sensor"
      json_attributes_template: "{{ value_json.Timer2 | tojson }}"
```

{% endraw %}

{% warning %}
If `json_attributes_topic` and `state_topic` share the same topic, a state update will happen only once, unless the state update did not change the state or `force_update` was set to `true`.

Setting up MQTT sensor's with extra state attributes that contain values that change at every update, like timestamps, or enabling the `force_update` option, is discouraged, as this will trigger state writes for every update. This can have a serious impact on the total system performance. A better option is creating separate sensors instead.
{% endwarning %}

### Usage of `entity_id` in the template

The example below shows how a simple filter, that calculates the value by adding 90% of the new value and 10% of the previous value, can be implemented in a template.

{% raw %}

```yaml
# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Temp 1"
      state_topic: "sensor/temperature"
      value_template: |-
        {% if states(entity_id) == None %}
          {{ value | round(2) }}
        {% else %}
          {{ value | round(2) * 0.9 + states(entity_id) * 0.1 }}
        {% endif %}
```

{% endraw %}

### Owntracks battery level sensor

If you are using the [OwnTracks](/integrations/owntracks) and enable the reporting of the battery level then you can use an MQTT sensor to keep track of your battery. A regular MQTT message from OwnTracks looks like this:

Topic: `owntracks/tablet/tablet`
```json
{
    "_type": "location",
    "lon": 7.21,
    "t": "u",
    "batt": 92,
    "tst": 144995643,
    "tid": "ta",
    "acc": 27,
    "lat": 46.12
} 
```

Thus the trick is extracting the battery level from the payload.

{% raw %}

```yaml
# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Battery Tablet"
      state_topic: "owntracks/tablet/tablet"
      unit_of_measurement: "%"
      value_template: "{{ value_json.batt }}"
```

{% endraw %}

### Temperature and humidity sensors

If you are using a DHT sensor and a NodeMCU board (esp8266), you can retrieve temperature and humidity with a MQTT sensor. A code example can be found [here](https://github.com/mertenats/open-home-automation/tree/master/ha_mqtt_sensor_dht22). A regular MQTT message from this example looks like this:

Topic: `office/sensor1`
```json
  {
    "temperature": 23.20,
    "humidity": 43.70
  }
```

Then use this configuration example to extract the data from the payload:

{% raw %}

```yaml
# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Temperature"
      state_topic: "office/sensor1"
      suggested_display_precision: 1
      unit_of_measurement: "°C"
      value_template: "{{ value_json.temperature }}"
    - name: "Humidity"
      state_topic: "office/sensor1"
      unit_of_measurement: "%"
      value_template: "{{ value_json.humidity }}"
```

{% endraw %}

### Get sensor value from a device with ESPEasy

Assuming that you have flashed your ESP8266 unit with [ESPEasy](https://github.com/letscontrolit/ESPEasy). Under "Config" set a name ("Unit Name:") for your device (here it's "bathroom"). A "Controller" for MQTT with the protocol "OpenHAB MQTT" is present and the entries ("Controller Subscribe:" and "Controller Publish:") are adjusted to match your needs. In this example the topics are prefixed with "home". Please keep in mind that the ESPEasy default topics start with a `/` and only contain the name when writing your entry for the {% term "`configuration.yaml`" %} file.

- **Controller Subscribe**: `home/%sysname%/#` (instead of `/%sysname%/#`)
- **Controller Publish**: `home/%sysname%/%tskname%/%valname%` (instead of `/%sysname%/%tskname%/%valname%`)

Also, add a sensor in the "Devices" tap with the name "analog" and "brightness" as value.

As soon as the unit is online, you will get the state of the sensor.

```bash
home/bathroom/status Connected
...
home/bathroom/analog/brightness 290.00
```

The configuration will look like the example below:

```yaml
# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Brightness"
      state_topic: "home/bathroom/analog/brightness"
```