The quickest way to change temperature units on a Honeywell thermostat

Most Honeywell thermostats let you switch between Celsius and Fahrenheit through the settings menu on the display itself. The exact steps depend on your model — some use a physical menu button, others use a touchscreen — but the process takes less than a minute once you find the right menu. You do not need to call a technician or reset the device.

The most common route is to press the Menu button on your thermostat's face, scroll to Settings or Preferences, find the Temperature Units or Display option, and toggle between °C and °F. After you make the change, the thermostat saves it automatically and displays all temperatures in your chosen unit from that point forward.

Key Takeaways

  • Press Menu on your thermostat's display, then navigate to Settings or Preferences to find the temperature unit option.
  • Touchscreen models often require you to swipe or tap a settings icon rather than press a physical button.
  • The change takes effect when ready and applies to both the display and any connected app or remote control.
  • If your model does not show a temperature unit option in the main settings, check the installer menu or consult your manual by model number.

Steps for button-based Honeywell thermostats

If your thermostat has physical buttons below or beside the display, start by pressing the Menu button. On most models this is labeled clearly, though on some older units it may say Select or Options instead. A menu will appear on the screen showing choices like Current, Schedule, Settings, or Preferences.

Use the up and down arrow buttons to scroll through the menu until you see Settings, Preferences, or Display. Press Select or Menu again to enter that section. Look for an option called Temperature Units, Display Units, or straightforward Units. Highlight it and press Select. You should see two choices: °C and °F. Press the arrow buttons to move between them, then press Select to confirm your choice. The display will update when ready.

If you do not see a temperature unit option in the main Settings menu, try scrolling further down — some models bury it under Advanced Settings or System Settings. If it is not there either, your thermostat may require access to the installer menu, which is password-protected on most units.

Steps for touchscreen Honeywell thermostats

Touchscreen models like the Honeywell Home T9 and T6 use a different interface. Look for a settings icon — usually a gear or three horizontal lines — on the main display screen. Tap it to open the settings menu.

Scroll down through the options by swiping up on the screen until you find Display Settings, Preferences, or Units. Tap that option. You should see a toggle or selection for Temperature Units or Display Format. Tap the option that shows °C or °F, and select the unit you want. The change saves automatically, and your display will switch within seconds.

Some newer touchscreen models also let you change the unit through the Honeywell Home app on your phone. Open the app, tap the thermostat, go to Settings, and look for Display or Units. The app and the physical thermostat will sync the change across both.

What to do if you cannot find the temperature unit setting

If you have scrolled through all visible menus and found no temperature unit option, your thermostat may not support user-facing unit changes, or the setting may be in the installer menu. The installer menu is usually locked behind a PIN code that only HVAC technicians have.

Check your thermostat's model number — it is usually printed on a sticker on the back or inside the battery compartment — and search for the manual online using that number. The manual will tell you whether your specific model can switch units and where that setting is located. If the manual confirms the feature exists but you still cannot find it, contact Honeywell customer support with your model number and they can walk you through the steps or provide the installer PIN if you own the thermostat.

If your thermostat is rented or part of a building system managed by your landlord or property manager, you may not have permission to change the unit setting. In that case, ask the property manager or building maintenance to make the change for you.

How the change affects your thermostat and connected devices

When you switch from Celsius to Fahrenheit (or vice versa), the thermostat converts all stored temperature settings automatically. If your heating was set to 20°C, it will display as 68°F after the switch. The actual temperature your system maintains does not change — only the way it is displayed and how you read it.

If you have a Honeywell Home app connected to your thermostat, the app will update to show the same unit within a few seconds. Any remote controls or wall-mounted displays linked to the same thermostat will also switch units. You do not need to change them separately.

Troubleshooting if the change does not stick

In rare cases, a thermostat may revert to its original unit setting after a power loss or battery replacement. If this happens, repeat the steps above to change it again. After you make the change, the new setting should remain even if power is lost, because the thermostat stores it in permanent memory.

If the unit keeps reverting even after multiple attempts, the thermostat may have a hardware issue or corrupted settings. Try removing the batteries (if it is battery-powered) for 30 seconds, then reinstalling them. This performs a soft reset without erasing your schedule or other settings. Then change the temperature unit again. If it still reverts, contact Honeywell support or have an HVAC technician inspect the device.

Frequently Asked Questions

Will changing the temperature unit affect my heating and cooling schedule?

No. Your schedule runs on the same temperatures — only the display changes. If you had heating set to turn on at 20°C, it will still turn on at that same point; the display will just show 68°F instead. All your programmed settings stay exactly as they were.

Can I change the unit from the Honeywell Home app instead of the thermostat itself?

On newer models like the T9, yes. Open the app, tap your thermostat, go to Settings, and look for Display or Units. Older models may not have this option in the app, so you may need to change it on the physical thermostat. Check your app's settings menu to see if the option is there.

What if my thermostat is a basic model without a display menu?

Very straightforward models with only up and down buttons and no screen cannot switch units — the unit is fixed at the factory. Check your manual or model number to confirm. If you need a different unit, you would need to replace the thermostat with one that supports both.

Do I need to turn off my heating or air conditioning to change the temperature unit?

No. You can change the unit while your system is running. The change takes effect when ready and does not interrupt heating or cooling. Your system will continue to maintain the temperature it was already set to.

Where do I find my thermostat's model number if I need to look up the manual?

The model number is usually on a sticker on the back of the thermostat or inside the battery compartment. It often starts with letters like T, RTH, or CT followed by numbers. Write it down and search for "[model number] manual" online to find the PDF from Honeywell or a retailer.