Get notified when the fridge door is left open

The idea

A contact sensor on the fridge or freezer door reports how long the door's actually been open, and a timed automation turns that into an alert before food spoils or energy gets wasted. It catches the problem while it's happening, not after you notice the fridge light's been on for twenty minutes.

What you'll need

• A door or reed contact sensor fitted to the fridge (and freezer, if it's separate), unless the fridge already has this built in as a smart-fridge feature.
• A hub or automation platform to time the open duration and send the alert.
• Optionally, a smart speaker or chime for an audible alert alongside (or instead of) a phone notification.

How the automation works

This one follows the same trigger, condition, action pattern as most sensor-based automations, with a reset built in:

• Trigger: the door sensor changes state to open.
• Condition: the door stays open continuously past your chosen threshold, commonly somewhere between 30 seconds and a few minutes: short enough to catch a mistake, long enough not to fire while you're grabbing a few items.
• Action: send a push notification, and optionally an audible chime through a smart speaker for anyone still in the house.
• Reset: the automation clears itself once the sensor reports closed again. No manual flag needed.

Common mistakes to avoid

• Setting the threshold too short. A few seconds will fire constantly during normal use: putting groceries away or grabbing several items in sequence can easily keep a fridge door open for 20 to 30 seconds without anything being wrong.
• Misaligning the sensor. A reed or magnetic contact sensor needs its two halves reasonably close and aligned. One mounted slightly off gives unreliable open/closed readings.
• Skipping the audible option. A phone notification is easy to miss if you're not looking at your phone. An audible chime through an existing smart speaker catches it faster if someone's still in the house.

Variations worth trying

Some recent smart fridges have this built in already, via an internal sensor and their own app, so it's worth checking before adding external hardware. The same door-sensor pattern extends to a pantry or cabinet inventory automation too: use the door open and close event as a cue to prompt an inventory check rather than just a left-open alert.