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Best Smoke Detectors and Fire Alarms of 2021

Smoke detectors and fire alarms help alert your family to a fire inside the home. In this review, the This Old House Reviews team delves into the best smoke detectors and fire alarms that can help alert you to an in-home emergency. The products included in this article are available at various home improvement stores, local home centers, and online retailers like Amazon.

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Protecting your home from fire damage and dangerous gases starts with installing the proper detection devices, like smoke detectors and carbon monoxide alarms. These easy-to-install and affordable devices can help you save not only your personal belongings but the lives of your loved ones that live inside the home.

While all smoke detectors and fire alarms are designed to catch high volumes of smoke inside your home, not all models work the same. That’s why purchasing the right smoke and carbon monoxide detectors for your home is important. To help you make an informed purchasing decision, the This Old House Reviews team researched the best smoke detectors, carbon monoxide detectors, and fire alarms on Amazon. Here are our top recommendations.

Best Smoke Detectors and Fire Alarms

While smoke detectors help you protect your home from dangerous fires by sensing the presence of smoke and emitting a warning sound, fire alarms typically work as a group to not only detect a fire but trigger actions to combat it, including contacting emergency services or setting off a sprinkler system. Usually, fire alarms signal a warning sound throughout the home or building as opposed to an isolated room or area. Here are five of the best smoke detectors and fire alarms on Amazon.

First Alert Smoke Detector and Carbon Monoxide Detector

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Available in a one- or three-pack, this First Alert detector offers two-in-one protection with its included smoke and carbon monoxide monitoring. The battery-operated device includes a mutable low-battery signal and an easy-access door that lets you replace its batteries without taking it down. In addition to its simple design, the smoke and carbon monoxide detector has a seven-year limited warranty and an end-of-life chirp that signals the need for a replacement.

X-Sense Smoke and Carbon Monoxide Detector

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This dual-sensing detector alerts homeowners to fire and carbon monoxide hazards in the home through its LCD and alarm horn. In addition to its carbon monoxide detection, this device displays your home’s carbon monoxide concentration levels to help you understand the severity of a leak.

This device is great for homeowners who are looking for an easy-to-read detector, and it comes with all the necessary installation hardware, including a mounting bracket, screws, and anchor plugs.

Kidde Hardwire Smoke and Carbon Monoxide Detector

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This smoke and carbon monoxide detector is hardwired into your existing electrical system and provides an additional layer of protection through its battery backup. The two-in-one detector supports many features that ensure it’s in working condition, including a tampering-detection alarm, adjustable mounting bracket, and battery door that only closes if the batteries are installed properly.

Additionally, the detector alerts homeowners to fire or carbon monoxide dangers through its LED status light and alarm.

Google Nest Protect Smoke and Carbon Dioxide Detector

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This smart fire alarm from Google detects dangerous levels of smoke and carbon monoxide in your home and is a solid choice for customers with existing smart home technology. Similar to traditional smoke detectors, this device triggers an alarm when it detects a fire or the presence of carbon monoxide.

However, this smart device differs from traditional models with its instant mobile notifications that alert you to a fire in your home even if you’re not there. Additionally, the alarm is equipped with voice alerts that let you know where the smoke or carbon monoxide is in your home.

Kidde Battery-Operated Smoke Alarm

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This affordable smoke detector from Kidde runs on a nine-volt battery and uses a flashing LED light and alarm to signal a fire. Although it’s a basic model, the device features a 10-year limited warranty and includes an easy-to-use test button to verify its operational status.

What To Consider Before Buying a Smoke Detector or Fire Alarm

Before purchasing a smoke detector or fire alarm, it’s important to understand how each device’s specifications and smoke-detecting sensors affect its performance. Here are some considerations to think about when buying a detector.


Most smoke detectors and fire alarms, including the Kidde Battery-Operated Smoke Alarm and X-Sense Smoke and Carbon Monoxide Detector, are designed with a 10-year battery life. While hardwired and battery-powered smoke detectors have similar lifespans, battery-operated models may require frequent check-ins to ensure the batteries aren’t dead.

Backup Power

Most smoke detectors and fire alarms are battery-powered or hardwired directly into your home’s electrical system. Typically, hardwiring the alarms calls for electrical expertise, which may require you to hire an electrician to install the smoke detectors. Battery-powered smoke detectors are easier to install because they run off of alkaline batteries and can detect smoke through power outages because they don’t rely on electricity.

Smart Capabilities

Some smoke detectors and fire alarms are equipped with smart features that send custom mobile alerts and communicate with surrounding devices. For example, the Google Nest Protect Smoke and Carbon Dioxide Detector sends you a mobile message when it detects smoke or carbon monoxide in your home.

Underwriters Laboratories Listing

The Underwriters Laboratories (UL) is a third-party certification company that has helped develop smoke alarm standards for over 40 years. A UL-certified smoke detector or fire alarm must meet the company’s requirements to receive its stamp of approval. Many smoke alarms, including the First Alert Smoke Detector and Carbon Monoxide Detector and Kidde Battery-Operated Smoke Alarm, meet UL requirements.

Type of Sensors

There are three different types of sensors inside a smoke detector, including a photoelectric sensor, an ionization sensor, and dual-sensing technology.


A photoelectric smoke alarm uses a light-sensitive sensor and an LED light to detect smoke. The smoke detector’s light sensor can’t pick up the LED light that’s emitted unless there’s smoke in the air, which causes the light to reflect and be picked up by the device’s sensor, triggering an alarm.


Ionization fire alarms like the Kidde Hardwire Smoke and Carbon Monoxide Detector use radioactive material that’s positioned between two electrically charged plates, which triggers air to flow from one plate to another. When smoke enters the detector, this airflow is restricted and triggers an alarm.

Dual sensors

Some smoke detectors, including the X-Sense Smoke and Carbon Monoxide Detector, use both ionization and photoelectric detectors to sense smoke and trigger an alarm. Utilizing both detection methods helps a device detect a range of fires while providing an alternative in case one method fails.

Top Brands

When it comes to smoke detectors and fire alarms, Kidde and First Alert lead the pack. Check out the history behind each company’s fire detection technology below.


Founded over 100 years ago, Kidde is one of the largest fire safety product manufacturers and produces devices like smoke detectors and carbon monoxide alarms. The company’s offerings go beyond just detection, as the company offers equipment like fire extinguishers and escape ladders that can help homeowners after a fire is detected.

First Alert

First Alert is a manufacturer of fire prevention devices and products, including smoke detectors, carbon monoxide alarms, fire extinguishers, and fire-resistant safes. The company created the first battery-powered smoke detector, which went on to earn a UL listing.

Best Carbon Monoxide Detectors

If your current smoke detector isn’t equipped with a carbon monoxide alarm, or you’re looking for added protection in a specific area of your home, a carbon monoxide detector is an affordable and convenient solution. Take a look at our top three recommendations.

Kidde Nighthawk Plug-In Carbon Monoxide Alarm

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This carbon monoxide detector plugs directly into a receptacle for long-lasting power and contains a nine-volt battery backup in case of an electricity outage. The plug-in detector operates in environments ranging between -40°F–100°F, perfect for homeowners looking for detection in poorly insulated areas of the home. Additionally, the device is available in a three-pack for multi-room protection.

Kidde Battery-Operated Carbon Monoxide Alarm

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This carbon monoxide alarm is a solid option for homeowners looking for a wall-mounted model. The device comes with a slide-out door for convenient battery access and can be fixed to any wall using screws. Additionally, the alarm displays your room’s carbon monoxide reading on its included display, which it updates every 15 seconds.

First Alert Carbon Monoxide Detector

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This detector from First Alert is a good choice for homeowners who want an affordable way to monitor carbon monoxide levels in their homes. The battery-operated detector emits a loud 85-decibel alarm when triggered and can be mounted to a wall or laid flat on any surface. Additionally, the device is protected with a seven-year limited warranty and is equipped with an end-of-life chirp that signals when it’s time for a replacement.

What To Consider Before Buying a Carbon Monoxide Detector

Before purchasing a carbon monoxide detector, consider the following three factors.

Power Source

Like smoke detectors, most carbon monoxide alarms are battery- or electric-powered. Instead of wiring directly into your home’s electrical system, many carbon monoxide alarms conveniently plug into a receptacle. Typically, electric-powered models offer a battery backup to keep the device running through a power outage.


Most carbon monoxide alarms, including the Kidde battery-operated and plug-in models, give the exact carbon monoxide reading in the room on a convenient display. Having an accurate carbon monoxide reading not only helps you assess the danger of your situation, but it also helps determine the location of a carbon monoxide leak.

Smoke Detection

While our recommended carbon monoxide detectors only sense high levels of carbon monoxide in your home, some models like the Kidde Hardwire Smoke and Carbon Monoxide Detector provide both smoke and carbon monoxide detection. If you’re looking for a dual-protection device, a more affordable and convenient option is to purchase a two-in-one product. If you just need carbon monoxide detection, one of the options above should do.

Where To Place the Devices Throughout Your Home

The National Fire Protection Association (NFPA) suggests installing a smoke detector in every hallway, level, and bedroom inside your home. The best place to install a smoke detector is on a ceiling, though you can install one on a wall if you position it within inches of your ceiling.

The NFPA recommends placing a carbon monoxide detector in every area you install a smoke detector. It’s important to remember to install carbon monoxide alarms away from flame-producing appliances, as this can trigger a false alarm.

Frequently Asked Questions

How often should I replace a smoke detector?

Most smoke detectors, including the First Alert Smoke Detector and Carbon Monoxide Detector, emit a chirp that signals the end of their working life. If you own a model that isn’t equipped with an end-of-life signal, you should replace the entire model after 10 years of use.

How can I tell if there’s carbon monoxide in the house?

Carbon monoxide is an odorless, tasteless, and colorless gas that can lead to serious health complications and possibly death if exposed to in high quantities. While the gas can’t be detected using taste, smell, or sight, it can cause symptoms like dizziness, shortness of breath, blurred vision, and confusion. A carbon monoxide detector can also detect high levels of carbon monoxide within your home and alert you when this occurs.

What can cause a carbon monoxide leak in the home?

Carbon monoxide is emitted by appliances like boilers and water heaters when their fuel source isn’t burned properly. Additionally, a car’s engine emits carbon monoxide while running, which can lead to health complications or death if you breathe in high levels of carbon monoxide inside an enclosed garage.

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