Home Assistant Fan Speed by Temperature: Setup and Pause

Start with a running fan, then adjust its speed

To set Home Assistant fan speed by temperature, use the built-in fan.set_percentage action with a room-temperature reading and a visible Auto speed switch. First confirm your fan accepts speed commands. Then rehearse the two-speed rule below before connecting it to the real device.

The household turns the fan on when someone wants a breeze and off when they leave. While Auto speed is enabled, Home Assistant chooses a slower or faster speed. There is no automatic start merely because the room is warm, and no temperature-based shutoff. That makes the controls easier to explain: the fan switch controls the motor; Auto speed controls who chooses the speed.

A circulating fan helps a person feel cooler; it does not refrigerate the room. Do not expect the thermometer to fall until the fan shuts itself off. The Department of Energy’s cooling guide (PDF) distinguishes room air circulation from cooling the building. Bathroom extraction belongs in our separate humidity-controlled bathroom fan guide.

Researched from current Home Assistant documentation on October 31, 2026. The example is a configuration walkthrough, not a tested fan installation. No noise, airflow, energy-saving or response-time measurements are claimed. The cover is an illustration.

1. Check the existing fan’s capabilities

An entity is a named control or reading in Home Assistant, such as fan.office. Its integration is the connection that makes it available. You need permission to create helpers and automations, an existing room sensor, and a fan already connected through an integration that supports speed control. The built-in helpers and actions below require no paid license or extra app.

On a phone, scroll sideways inside the table.

Home Assistant represents supported speeds as percentages, but a three-speed fan still has three speeds. A request for 40% does not create a fourth motor setting. Presets can also control speed themselves. These distinctions follow the fan entity contract; check the documentation for your particular integration before enabling the routine.

2. Choose two speeds and two temperature boundaries

This example uses 33% and 100% for a hypothetical three-speed room fan. Those are demonstration settings, not universal comfort recommendations. Later, replace them with the two values your fan actually accepts and reports.

• Above 25.5°C: request the faster speed.
• Below 24.5°C: request the slower speed.
• From 24.5°C through 25.5°C, including both exact boundaries: keep the current speed.

This gap prevents small temperature changes near 25°C from repeatedly switching speeds. That behavior is called hysteresis. Our Threshold helper guide explains the same idea for a reusable on/off status; this routine compares the reading directly and keeps the fan’s reported speed inside the gap.

Match the numbers to the source reading’s unit. For a Fahrenheit sensor, the equivalent boundaries are 76.1°F and 77.9°F. The templates below compare numbers; they do not convert units automatically. On restart inside the gap, the routine leaves whatever speed the fan reports, rather than restoring an earlier preference.

3. Rehearse without controlling a real fan

A helper is a virtual control stored in Home Assistant. This rehearsal changes only a number helper. Keep these demo helpers out of existing groups, labels and routines that control equipment.

1. Go to Settings → Devices & services → Helpers → Create helper. Create two Toggle helpers named Fan demo running and Fan demo auto. Keep both off initially.
2. Create a Number helper named Fan demo temperature, minimum 15, maximum 35, step 0.1, unit °C. Set it to 24.
3. Create another Number helper named Fan demo speed, minimum 0, maximum 100, step 1, unit %. Set it to 33. Put all four helpers on a dashboard so you can see their changes.
4. Open Settings → Automations & scenes, create a new empty automation, and use its menu’s Edit in YAML option. Paste the rehearsal below and replace example entity IDs with the actual IDs shown in your helper settings. Save it. Menu wording can differ across releases.
5. Turn both demo toggles on and follow the table in order. Change the helpers themselves to trigger the automation; do not use Run actions, which is not a test of its triggers and top-level conditions.

The Number helper supplies the pretend temperature and displayed speed. The Toggle helpers stand in for a running fan and permission to adjust it.

On a phone, scroll sideways inside the code box and copy the entire example.

alias: Fan speed temperature rehearsal
mode: restart
triggers:
  - trigger: state
    entity_id: input_number.fan_demo_temperature
    to: null
  - trigger: state
    entity_id:
      - input_boolean.fan_demo_running
      - input_boolean.fan_demo_auto
    to: "on"
  - trigger: homeassistant
    event: start
  - trigger: time_pattern
    minutes: "/5"
conditions:
  - condition: state
    entity_id: input_boolean.fan_demo_auto
    state: "on"
  - condition: state
    entity_id: input_boolean.fan_demo_running
    state: "on"
actions:
  - variables:
      temperature: "{{ states('input_number.fan_demo_temperature') }}"
      current_speed: "{{ states('input_number.fan_demo_speed') }}"
      low_speed: 33
      high_speed: 100
  - condition: template
    value_template: >-
      {{ is_number(temperature) and is_number(current_speed) }}
  - variables:
      requested_speed: >-
        {% if temperature | float > 25.5 %}
          {{ high_speed }}
        {% elif temperature | float < 24.5 %}
          {{ low_speed }}
        {% else %}
          {{ current_speed | float }}
        {% endif %}
  - condition: template
    value_template: >-
      {{ ((requested_speed | float) -
          (current_speed | float)) | abs > 2 }}
  - condition: template
    value_template: >-
      {{ is_state('input_boolean.fan_demo_auto', 'on') and
         is_state('input_boolean.fan_demo_running', 'on') }}
  - action: input_number.set_value
    target:
      entity_id: input_number.fan_demo_speed
    data:
      value: "{{ requested_speed | int }}"

Expected results from the rule, not measurements from hardware. Wait for each result before continuing.

The Running toggle does not itself change the demo speed; it only stands in for the real fan’s on/off report. Step 7 therefore sets both values explicitly. If a row fails, inspect the automation’s trace before connecting equipment. A trace is the record of which trigger, conditions and actions ran.

4. Connect the rule to one room fan

1. Disable the rehearsal automation. Leave its helpers separate from the real routine.
2. Create a Toggle helper called Office fan auto speed and turn it off. In the current documented UI, expand More options → Each time Home Assistant starts and choose Turn off if you want to re-enable Auto deliberately after a restart. This startup setting does not turn the helper off now; do both steps. Pausing leaves the motor and its present speed alone.
3. Confirm the actual controls. With someone in the room, use the fan’s supported controls to select a comfortable lower and higher speed. Check that Home Assistant reports both correctly, and that turning the fan off physically changes its entity to off. Stop here if feedback is unreliable.
4. Create a separate live automation using the code below. Replace sensor.office_temperature, fan.office and input_boolean.office_fan_auto_speed everywhere with your actual IDs. Set low_speed and high_speed to accepted reported values; adapt both temperature numbers if your sensor uses Fahrenheit.
5. Check every target and keep Auto speed off while saving. Then turn the fan on normally, enable Auto speed and observe it. Above the upper boundary it should select the higher speed; below the lower boundary it should select the lower speed; in the gap it should leave the speed alone. Pause Auto before making further manual adjustments.

alias: Office fan automatic speed
mode: restart
triggers:
  - trigger: state
    entity_id: sensor.office_temperature
    to: null
  - trigger: state
    entity_id:
      - fan.office
      - input_boolean.office_fan_auto_speed
    to: "on"
  - trigger: homeassistant
    event: start
  - trigger: time_pattern
    minutes: "/5"
conditions:
  - condition: state
    entity_id: input_boolean.office_fan_auto_speed
    state: "on"
  - condition: state
    entity_id: fan.office
    state: "on"
actions:
  - variables:
      temperature: "{{ states('sensor.office_temperature') }}"
      current_speed: "{{ state_attr('fan.office', 'percentage') }}"
      low_speed: 33
      high_speed: 100
  - condition: template
    value_template: >-
      {{ is_number(temperature) and is_number(current_speed) }}
  - variables:
      requested_speed: >-
        {% if temperature | float > 25.5 %}
          {{ high_speed }}
        {% elif temperature | float < 24.5 %}
          {{ low_speed }}
        {% else %}
          {{ current_speed | float }}
        {% endif %}
  - condition: template
    value_template: >-
      {{ ((requested_speed | float) -
          (current_speed | float)) | abs > 2 }}
  - condition: template
    value_template: >-
      {{ is_state('input_boolean.office_fan_auto_speed', 'on') and
         is_state('fan.office', 'on') }}
  - action: fan.set_percentage
    target:
      entity_id: fan.office
    data:
      percentage: "{{ requested_speed | int }}"

The Set fan speed action targets one specific fan. The routine skips a speed command when the reported speed is already within two percentage points of the request; this accommodates small rounding differences. Choose speeds farther apart than that. It also ignores changes to the fan’s speed attribute as triggers, avoiding a loop caused by its own action.

Temperature updates, enabling Auto, a fan becoming on, Home Assistant startup, and a five-minute check can each run the rule. The periodic check reads Home Assistant’s stored states; it does not force the thermometer to send a fresh sample. These are triggers followed by conditions, so every normal run requires Auto on and a fan reported on. Those two conditions are checked again just before the speed action, including when actions are run manually.

5. Make pause and failure behavior visible

Put Auto speed beside the fan control and temperature reading on the household dashboard. Turn Auto off before choosing a speed you want to keep. Changing the speed alone does not pause this example: the next temperature update or periodic check may replace it. Our manual-override guide covers wider household pause rules.

The default Toggle helper setting restores its previous state after a restart. With that default, Auto can resume once readings are usable. The current Toggle documentation also provides a Turn off at startup option, recommended here for deliberate re-enabling. If your installed version does not expose that option, do not assume it starts off: keep the restore behavior in your household instructions and leave Auto off before a planned restart.

Unknown or unavailable temperature and speed readings fail the numeric check, so no new speed command is sent. The motor may keep running at its last setting. A numeric reading that has stopped updating can still pass, and a delayed on/off report can be wrong. This rule cannot guarantee that a physical stop and a nearly simultaneous speed command will never cross. Pause Auto first when taking manual control, and keep the fan’s normal physical controls usable.

Use this only for ordinary room comfort, with the fan installed and used as its manufacturer directs. Do not apply it to required ventilation, smoke extraction, equipment cooling or any other safety function. Running the automation locally does not make a cloud-connected fan local: the sensor and fan integrations determine their own data and control paths.

If the behavior is unexpected

Scroll sideways to read all three columns.

Frequently asked questions

Can a smart plug vary a fan’s speed?

An on/off smart plug does not provide the fan’s speed controls. This example requires an integrated fan that accepts percentage speed commands. Follow the appliance and control manufacturer’s compatibility instructions.

Does pausing Auto speed turn the fan off?

No. It prevents this automation from issuing new speed commands. Use the fan’s normal control to stop the motor.

Will this work without internet?

The automation runs on Home Assistant, but its input and output paths also matter. Both the temperature sensor and fan must remain accessible through their integrations. A cloud-dependent fan connection does not become local because the rule runs at home.

Can I use the fan’s built-in Auto mode instead?

Yes, when its own sensor and behavior suit the room. Choose that controller or this Home Assistant routine deliberately, and verify the controls your exact integration exposes. Do not assume preset support also means percentage-speed support.