15 Best Carbon Monoxide Detectors: The 2024 Safety Guide
Protect your family from the “Silent Killer” with our top-rated picks for every home and budget.
Carbon monoxide (CO) is terrifying for one specific reason: it is invisible, odorless, and tasteless. Often referred to as the “silent killer,” this gas can accumulate in your home from malfunctioning gas appliances, blocked fireplace vents, or idling cars in attached garages. Without a reliable detector, you simply won’t know it’s there until it is too late.
Whether you have a wood stove, a gas furnace, or simply an attached garage, a high-quality CO detector is non-negotiable. But with hundreds of models on the market—ranging from basic plug-ins to smart Wi-Fi enabled devices—finding the right one can be overwhelming.
We have tested and analyzed the market to bring you the 15 best carbon monoxide detectors available today. We evaluated them based on sensor accuracy, ease of installation, smart features, and battery life.
Quick Comparison: Top 5 Picks
| Model | Best For | Power Source | Smart Features |
|---|---|---|---|
| Google Nest Protect | Overall Best (Smart) | Battery or Hardwired | Yes (Wi-Fi) |
| First Alert CO615 | Best Plug-In | Plug-in + Battery Backup | No |
| Kidde Nighthawk | Best Value | Plug-in or Battery | No |
| First Alert Onelink | Alexa Users | Hardwired | Yes (Alexa) |
| X-Sense SC03 | Best Combo | 10-Year Battery | No |
What to Look for in a CO Detector
Before diving into the reviews, it helps to understand the technology. Not all detectors are created equal. Here are the critical factors to consider:
1. Sensor Technology
Most modern detectors use electrochemical sensors. These are highly accurate and react quickly to rising CO levels. They are generally superior to older biometric or metal oxide sensors. Because CO is a byproduct of incomplete combustion, ensuring your gas fireplace venting options are up to code is just as important as the detector itself.
2. Power Source
- Hardwired: connects to your home’s electricity (usually required for new construction).
- Battery-Operated: easy to install anywhere; look for sealed 10-year lithium batteries to avoid the “low battery chirp.”
- Plug-In: plugs into a standard wall outlet, usually with a battery backup.
3. Interconnectivity
In larger homes, interconnectivity is a life-saver. If the alarm in the basement goes off because of a fireplace draft problem, the alarm in your upstairs bedroom will also sound.
Detailed Reviews: The 15 Best Carbon Monoxide Detectors
1. Google Nest Protect (2nd Gen)
The Google Nest Protect isn’t just a CO detector; it’s a comprehensive home safety device. It detects both smoke and carbon monoxide and uses a friendly human voice to tell you exactly what the danger is and where it is located.
Why We Love It
The “Heads-Up” feature gives you a gentle warning before a full-blown alarm, which is great for burnt toast. However, for CO, it sends alerts directly to your phone. This is crucial if you are away from home and have pets inside. It also performs its own self-checks, so you don’t have to wonder if it’s working.
Pros
- Voice alerts specify the hazard and room.
- Smartphone notifications.
- Split-Spectrum sensor detects fast and slow fires.
- Interconnects wirelessly with other Nest units.
Cons
- Higher price point.
- Requires Wi-Fi for full features.
2. Kidde Nighthawk Plug-In with Battery Backup
The Kidde Nighthawk is a classic for a reason. Its standout feature is the digital display, which updates every 15 seconds to show current CO levels in parts per million (PPM).
Why We Love It
Seeing “0” on the display provides immense peace of mind. Many detectors only alarm when levels are dangerous, but the Nighthawk lets you see if low levels are present, which might indicate a small leak in your kitchen chimney or venting system before it becomes critical.
Pros
- Easy-to-read digital display.
- Peak level button shows the highest CO reading since reset.
- Plug-in design is effortless to install.
Cons
- Not aesthetically modern.
- Cord can be unsightly if outlet is high up.
3. First Alert CO615 Dual-Power
Similar to the Nighthawk but often at a slightly more competitive price point, the First Alert CO615 is a reliable workhorse. It features a backlit display that is easy to read at night.
Why We Love It
The versatility of installation is great. You can plug it directly into the wall, or use the line cord to mount it higher on the wall (closer to eye level). It has a battery backup, ensuring protection even during winter power outages—a common time for CO incidents due to alternative heating use like firewood burning.
Pros
- Backlit display for night viewing.
- Single button for test and silence.
- 7-year limited warranty.
Cons
- Battery compartment can be tricky to open.
4. First Alert Onelink Safe & Sound
This is a premium hardwired smoke and carbon monoxide detector that doubles as an Alexa-enabled smart speaker. It’s a 3-in-1 device designed for the modern smart home, eliminating the need for separate Echo dots on your ceilings.
Why We Love It
It installs on the ceiling like a standard hardwired detector but brings high-end audio and voice assistance. If you are renovating and wondering which services to use for electrical safety, adding these hardwired smart units increases home value significantly. The nightlight feature is customizable, which is a nice touch for hallways.
Pros
- Built-in Alexa Voice Services and high-end speaker.
- Compatible with Apple HomeKit (AirPlay 2).
- Customizable nightlight color and brightness.
- Hardwired with 10-year battery backup.
Cons
- Significantly more expensive than standard units.
- Physically larger and heavier than typical detectors.
- Requires existing hardwiring (not for battery-only setups).
5. X-Sense SC0C
The X-Sense SC0C combines smoke and CO detection in one sleek unit with a sealed battery. This means no battery changes for a decade, solving the annoyance of 2 AM low-battery chirps.
Why We Love It
The LCD display provides real-time status, and the LED ring changes color based on the status (Green for normal, Yellow for fault, Red for alarm). It is incredibly sensitive, which is vital if you are dealing with subtle issues like a leaky chimney allowing gases to seep back in.
Pros
- Sealed battery (maintenance-free).
- informative LCD display showing CO levels.
- 3-color LED status ring gives visual cues.
- Sleek, modern aesthetic compared to older brands.
Cons
- Once the battery dies , the whole unit must be trashed.
6. Kidde Battery-Operated CO Alarm
Simple, effective, and extremely affordable. This basic unit runs on AA batteries and does exactly what it needs to do without bells and whistles. It’s the standard for landlords and budget-conscious homeowners.
Why We Love It
If you need to outfit a large house on a budget, this is the pick. It’s also great for travel or cabins where you might be using wood stoves vs fireplace heating occasionally. The “slide-out” battery door makes changing batteries easy without taking the unit off the wall.
Pros
- Extremely affordable price point.
- Runs on standard AA batteries (included).
- Easy slide-out battery door.
- Loud 85-decibel alarm.
Cons
- No digital display to see low-level CO.
- Requires annual battery changes.
- Basic utilitarian design.
7. First Alert SCO5CN Combination Alarm
This battery-operated unit detects both smoke and CO and uses programmable voice alerts to distinguish between the two. You can program it to say “Fire in the Kitchen” or “Warning, Carbon Monoxide in the Basement.”
Why We Love It
Voice alerts are superior to simple beeps because they reduce panic and confusion. Knowing exactly where the danger is helps you plan your escape route, especially if the issue is related to a chimney fire or a furnace leak.
Pros
- Voice alert system eliminates confusion.
- Photoelectric smoke sensor reduces false alarms from cooking.
- Battery drawer allows changes without dismounting.
- One button silences both smoke and CO alarms.
Cons
- Voice test can be very loud and startling.
- Slightly larger diameter than standard alarms.
8. Kidde Sealed Lithium Battery Power
This unit is tamper-proof and designed to last 10 years. Once activated, it cannot be turned off until the end of its life, making it extremely safe for rentals where tenants might be tempted to remove batteries to stop a chirp.
Why We Love It
It activates automatically when you attach it to the mounting bracket. It’s perfect for high-up places like cathedral ceilings near a chimney cap access point where you don’t want to drag a ladder out every year.
Pros
- True 10-year lifespan with no battery changes.
- Tamper-resistant (great for landlords).
- Event memory flashes if CO was detected while you were away.
- Simple “slide to activate” installation.
Cons
- No digital display.
- If the unit malfunctions, you can’t just swap the battery; you must replace the unit.
9. Universal Security Instruments Hardwired
A great option for replacing existing hardwired detectors without breaking the bank. It includes a backup battery and a quick-draw drawer for easy battery replacement without removing the unit from the ceiling wiring harness.
Why We Love It
USI is a trusted brand in the industry. This model is particularly good for retrofitting older homes that already have USI brackets installed. It’s a solid choice if you are doing a full home renovation, perhaps while insulating your chimney chase and updating electricals.
Pros
- Front-loading battery drawer is convenient.
- Large silence/test button is easy to hit with a broom handle.
- Universal mounting bracket fits most junction boxes.
- 5-year warranty.
Cons
- The design looks a bit dated compared to Nest or X-Sense.
- Hardwired installation requires electrical knowledge.
10. Forensics Detectors Low Level CO Monitor
Standard UL-listed detectors only alarm at high levels (70ppm+). This unit detects low levels (9ppm+), making it ideal for the elderly, infants, or those with respiratory issues or heart conditions.
Why We Love It
It fills a gap in the market for health-conscious individuals who want to know about small leaks before they become life-threatening. This sensitivity is crucial if you have older appliances or suspect smoke coming into the house is carrying invisible CO.
Pros
- Detects low levels of CO (9ppm) that others miss.
- Fast response time (within 60 seconds).
- High-quality Japanese electrochemical sensors.
- Alarms at 25ppm (much earlier than UL standards).
Cons
- More expensive than standard home detectors.
- Requires battery replacement more frequently due to sensitivity.
11.Portable Travel CO Detector
Small enough to fit on a keychain or in a pocket. This is essential for travelers staying in hotels or Airbnbs where detector maintenance is unknown, or for use in vehicles and tents.
Why We Love It
It’s rechargeable via USB and includes a flashlight. We recommend this for anyone who frequently camps or uses chimney starters and grills near their camping area.
Pros
- Extremely compact and lightweight.
- Rechargeable lithium battery (USB-C).
- Color display screen.
- Double use as an emergency flashlight.
Cons
- Not UL-2034 listed for permanent home installation.
- Battery life requires monitoring (needs charging).
12. First Alert Slim Photoelectric Smoke & CO
This unit has a low profile, sticking out half as much as standard bulky detectors. It blends seamlessly into modern ceilings and uses a twist-lock mounting system.
Why We Love It
Aesthetics matter. If you have spent time choosing the best paint for your chimney brick and interior walls, you don’t want an ugly plastic mushroom on your ceiling. The “Slim” series offers protection without the bulk.
Pros
- Modern, low-profile design.
- Photoelectric sensor detects smoldering fires better.
- Resistant to nuisance alarms from cooking steam.
- Battery-operated for flexible placement.
Cons
- Test button can be hard to distinguish from the casing.
- LED indicator is quite bright in dark rooms.
13. Siterwell Wi-Fi Smoke & CO Detector
A cheaper alternative to Nest, this unit connects to the Tuya/Smart Life app. It sends notifications to your phone whenever an alarm is triggered or the battery is low, without the premium price tag.
Why We Love It
It brings smart safety to the masses. Being able to check the battery status from your phone is a huge plus. It integrates well into homes that already use Tuya-based smart devices for things like electric fireplace controls.
Pros
- Real-time smartphone notifications.
- Significantly cheaper than Nest or Onelink.
- Works with Tuya and Smart Life apps.
- Includes self-check function.
Cons
- Setup can be finicky on 5GHz Wi-Fi networks (needs 2.4GHz).
- Build quality feels lighter/cheaper than premium brands.
14. Kidde KN-COB-B-LPM
Another strong entry from Kidde, specifically designed with LED indicators for operation status. It’s a no-nonsense, highly rated battery unit that has protected millions of homes.
Why We Love It
It is small, loud, and reliable. The Green/Red LED system is intuitive—if it flashes red, get out. It’s a great backup unit to place near gas fireplace venting areas where space might be tight.
Pros
- Compact design fits anywhere.
- Loud 85dB alarm pattern.
- Battery lockout system prevents installation without batteries.
- Test/Reset button is easy to access.
Cons
- No digital readout.
- Mounting bracket is a bit flimsy.
15. VITITE Safe-T-Alert
Specifically designed for RVs, campers, and motorhomes, this unit detects both Carbon Monoxide and Propane leaks. Standard home detectors often fail in RVs due to temperature extremes and vibration.
Why We Love It
It wires directly into the RV’s 12V system, so you never have to worry about changing batteries. Since RV spaces are small, a propane leak from a stove or a CO leak from a ventless gas fireplace can be fatal in minutes. This dual protection is mandatory for road trips.
Pros
- Dual detection: Propane (explosive) and CO (toxic).
- Hardwired 12V operation (no batteries to change).
- Designed to withstand road vibration and temp swings.
- Flush mount design looks professional.
Cons
- Parasitic draw on your RV battery (be careful in storage).
- Not suitable for standard residential homes (12V only).
Where to Place Your CO Detectors
Buying the best detector is only half the battle; correct placement is vital.
- Sleeping Areas: Install one within 10 feet of every bedroom door.
- Every Level: Place at least one on every floor, including the basement.
- Attached Garage: Place one inside the house near the door to the garage, but not inside the garage (temp fluctuations can damage sensors).
- Chimney Proximity: If you have a fireplace, place a detector in the same room, but at least 15 feet away from the source to prevent false alarms. If you notice chimney fire signs, evacuate immediately regardless of the alarm.
Common Causes of CO Buildup
Understanding the source helps prevention. Common culprits include:
- Clogged Chimneys: Birds or debris can block airflow. If you suspect an animal, learn how to get a bird out of your chimney safely.
- Cracked Heat Exchangers: In furnaces, this allows gas to mix with house air.
- Portable Generators: Never run these indoors or near windows.
Frequently Asked Questions
A chirp usually indicates a low battery or the “end of life” signal. If it is a rhythmic pattern (e.g., 4 beeps, pause), it is an emergency alarm—evacuate immediately. If it’s a single chirp every minute, replace the battery.
No. Phones do not have the electrochemical sensors required to detect carbon monoxide gas. “Detector apps” are usually pranks or require external hardware.
Press and hold the “Test” button on the unit. This checks the battery and circuitry. To test the sensor itself, you can buy a can of CO test spray, though this is usually reserved for professionals.
While insurance covers damages, prevention is key. Many providers offer discounts for having monitored smoke and CO systems. Read more about homeowners insurance and chimney repair here.
Final Verdict
Carbon monoxide safety is not an area to cut corners. For the best overall protection, we recommend the Google Nest Protect due to its smart interconnectivity and voice alerts. For a budget-friendly yet reliable option, the Kidde Nighthawk remains the gold standard for its visual digital display.
Remember, these devices have an expiration date. If your current detectors are over 7 years old, it is time to replace them today. Stay safe!