7 Best Ketone Breath Meters That Actually Work (2023)

A ketone breath meter is the fastest and most convenient way to measure ketones, period.

The best ketone breath meter is easy to use, convenient to carry around, and provides precise results.

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Best for Keto

Best for Low-Carb


Most Accurate Results

Best Ketone Breath Meters

1. Keyto

The Keyto ketone breath meter is probably the most popular breathalyzer among the keto community. 

It’s designed like a keto pen that is convenient in size and it feels good in the hand. It weighs only 0.95 ounces (27g), and one battery lasts over 600 breath measurements.

The Keyto sensor measures the acetone levels in your breath and lets you know if you are burning fat or sugar for energy.

It works as advertised and is actually simple to use. I especially liked how the device also comes with an app and community. 

The app is surprisingly well done, with lots of recipes, great food recommendations, and a helpful plan for the first seven days, including a shopping list. 

  • I don’t like that it takes a bit of time to warm up for each use. Although that’s not a deal breaker overall, as the readings are accurate, and it’s still 10 times faster than urine strips or blood meters when I’m on the go.
  • Another negative aspect is that the device itself cannot show a reading. Instead, you can see it from a mobile device. Yet, thanks to the missing screen, the price is very reasonable.

The keto breath sensor package comes with a Keyto device, a carrying case, one AAA battery, and four mouthpieces.

What We Liked

  • Best keto breath meter for beginners
  • Provides accurate readings
  • Offers lots of value for the money
  • Very simple to use and provides fast results
  • Feels good in the hand and is easy to carry around
  • The app provides lots of practical information for beginners

What Can Be Improved

  • No device screen, you need to use the app to get a reading
  • Unable to pair with more than 1 app 
  • No instructions on how to use it in the box
  • Takes a bit of time to heat up

Best for: Keto beginners
App: Android and IOS
Weight: 0.95 ounces (27 g)
Battery: 600+ breath tests (one AAA battery)
Dimensions: Height 5.5 in (14cm) x Width 0.5 in (1.27cm)

2. Lumen

Lumen is a breathalyzer that measures CO2 concentration in your breath and tells you if your body is using carbs or fats for energy. 

PS! It’s not designed for the keto diet and doesn’t measure acetone levels, like the Keyto meter. Although the end result might be somewhat similar.

But, Lumen works well for people who are struggling with the strict keto diet but still prefer to limit their carb intake without necessarily getting into ketosis.

This breath sensor is especially useful for learning about how your body reacts to carbs and fats and how your metabolism jump between energy sources.

  • In the beginning, I found it frustrating to exhale with the right intensity and it asked me to repeat it several times. It does have visual guidance, so the problem was in me, not in the device.
  • Another thing I didn’t like is that because the device doesn’t have a screen, I was forced to check my phone first thing in the morning to check my readings. This, again, isn’t a dealbreaker, but it would be nice to see the readings data without the phone. 

Lumen breath meter also comes with an app that is easy to use and well-designed. 

The app gives specific macronutrient ratio suggestions based on your breath so you can get into fat-burning mode. Long gone are the days when you need to calculate your macros yourself.

What We Liked

  • Best low-carb breath meter
  • Works well with low-carb diets but isn’t as restrictive as keto
  • Well designed and feels premium in hand
  • Effective as a motivational tool
  • App offers recipes and you can add or remove ingredients
  • Provides precise RER measurements (peer-reviewed)
  • Great holistic weight loss solution 

What Can Be Improved

  • Sometimes the app asks several times to take measurements
  • Measurements sometimes take more time compared to Keyto
  • Doesn’t have a screen, requires an app to take measurements

Best for: Low-carb dieters
App: Android and IOS
Weight: 2.6 ounces (75 g)
Battery: About 14 days
Dimensions: Height 4 in (102 mm) x Width 3.1 in (79.5 mm)

3. Biosense

Biosense is the best ketone breath analyzer when it comes to accuracy, period.

It uses an acetone sensor like other breath meters, but the most unique feature it has is that it measures the end of the breath sample, which provides the most accurate readings.

Biosense ketosis breathalyzer is FDA Class 1 medical device and currently going through clinical trials.

The coolest feature is that when blowing into the device, you feel a subtle haptic feedback sequence of two short bumps that indicates when to stop blowing.

  • The main negative aspect, I feel, is that they suggest recalibration of the sensor for every 6 months. You will need to ship it to Biosense and once they recalibrate the sensor, they will send it back to you.
  • The process will take 6-10 days and after the first year of warranty, will cost $74.99.
  • This recalibration process definitely feels annoying, especially when you need to pay for it. At the same time, if high accuracy is important to you, it’s definitely worth it.

I also really liked that it has a screen for fast readings, so I don’t need to watch my phone screen first thing in the morning.

The package comes with a Biosense device, a carrying case, two mouthpieces, and a charging cable.

What We Liked

  • Most accurate ketone breathalyzer
  • FDA-registered Class I medical device backed by clinical trial data
  • Has a screen, so you don’t need to use a smartphone first thing in the morning
  • Automatically syncs with the app for convenient tracking
  • Uses end-of-breath sampling for the most accurate reading
  • Haptic feedback tells you when to stop breathing into the device

What Can Be Improved

  • Takes a bit to warm up before you can use it
  • Device homepage is cheaply designed, doesn’t build trust
  • A higher price tag

Best for: Most accurate breath acetone meter
App: Android and IOS
Weight: n/a
Battery: 2-4 days
Dimensions: Length 4.375 in (11.1 cm) x Width 2.06 (5.2 cm) x Depth 0.81 (2.1 cm)

4. Ortorex Greenwon

The Greenwon keto breath tester by Ortorex is a great budget option to consider.

The Greenwon keto breathalyzer measures the acetone levels on your breath and tells you if you are in ketosis or not.

I liked that it has a simple traffic light system indicating the level of ketosis you are. 

Green indicates you are not in ketosis, orange indicates you are in light ketosis, and red indicates you are in a medium or higher level of ketosis.

It works with a single button, so it’s extremely simple to use, even if it’s your first time getting into ketosis.

  • The main negative feedback I have is that it cannot be synced with a smartphone, so you don’t get modern perks like measurement tracking, community, and recipes.
  • Another note is that the device feels a bit cheap in hand compared to other devices in this list. I think this is expected when considering the price, but it’s a factor if you like beautiful things.

The breath ketone monitor has a warmup period, like other breathalyzers and displays results in 10 seconds. The package comes with the Greenwon device, four mouthpieces, and a carrying pouch

What We Liked

  • Best budget keto breath analyzer
  • Comes with a screen, so you don’t need to check your phone first thing in the morning
  • Has a simple traffic light system results system indicating the state of ketosis
  • Compact design making it easy to follow keto on the go
  • Very affordable price for the value it provides

What Can Be Improved

  • Feels a bit cheap in the hand
  • Not possible to sync with a smartphone
  • Not FDA-approved device

Best for: Best budget option
App: n/a
Weight: n/a
Battery: 2-4 days
Dimensions: n/a

Related: 5 Best Metabolism Trackers for Weight Loss


The LEVL ketone breath analyzer measures acetone levels in your breath and is designed for a clinical setting.

It’s FDA cleared point-of-care device and is highly accurate and provides readings within 15 seconds.

The reading results have been tested and validated to 91% of the LEVL measurements were within ± 1.0 ppm of the mass spectrometer. Which is very good.

I also like that LEVL is owned by and made in the U.S.

  • The main negative aspect is that it’s designed for a clinical setting, so we cannot buy it yet as consumers.
  • Another negative aspect is that the device needs to be calibrated every 14 days for accuracy. Which is understandable but tedious, especially when there are better alternatives like Keyto or Biosense.

What We Liked

  • Best ketosis breath meter for a clinical setting
  • FDA-registered point-of-care device
  • Offers very accurate readings
  • Device can track the measurements of two users
  • Comes with a screen, so a smartphone isn’t essential for readings

What Can Be Improved

  • Isn’t available for consumers yet
  • Physically bulky, so not a great option when on the go
  • Needs to be calibrated every 14 days for accuracy

Best for: Clinical setting
App: Android & IOS
Weight: n/a
Battery: No battery
Dimensions: n/a

6. Ketonix


Ketonix ketosis breath meter is probably one of the oldest keto breath meter brands out there. It analyzes your breath for acetone and indicates if you are burning fat or carbs for energy.

The biggest advantage over competitor devices is that the sensor doesn’t need to be replaced and it can be used for years.

The Ketonix keto breath analyzer is designed and owned by a Swedish company, but they offer worldwide shipping. 

The founder of Ketonix developed the device when he found out that he had epilepsy. This indicates that the company is managed on the right grounds to actually help its customers.

The device supports Bluetooth, WIFI, USB connections and can be used only with a smartphone app.

  • The main negative aspect for me is that Ketonix doesn’t have a screen. So I always need to connect it to a smartphone, which is tedious if I try to minimize the blue screen time.
  • They also offer software upgrades for analysis package, macro calculator, recipes, and experiments. This feel odd, as you get all of that for free with competitor devices like Keyto or Biosense.

The keto breath tester package comes with a Ketonix device, a travel pouch, a charging cable, and two mouthpieces.

What We Liked

  • Best keto breathalyzer for home use
  • Oldest known breathalyzer brand
  • Sensor doesn’t need to be replaced
  • Easy to use and practical smartphone app
  • Compact design and perfect to use on the go

What Can Be Improved

  • Device doesn’t have a screen, so you always need to use a smartphone
  • Paid software upgrade features come free with Keyto and Biosense meters
  • Takes up to 5 minutes for warm-up, depending on the room temperature

Best for: Home use
App: Android and IOS
Weight: 2.5 ounces (70 grams)
Battery: Integrated
Dimensions: Length 5.1 in (130 mm), Diameter 0.98 in (25 mm)

7. Acetrack


Acetrack is a keto breath meter with an acetone sensor to track your state of ketosis. It was developed by a Swedish company called Deversify.

The Acetrack device is physically very compact and discrete and it’s easy to use when on the go. 

This keto breathalyzer doesn’t have a screen, so you always need to have a smartphone at hand to get the readings.

What I really liked is that one device can be used by several accounts, so your measurements don’t get mixed with your family members’ readings.

The device comes with an integrated, easy-to-use app to track and analyze your progress.

  • The main negative comment I have is that sometimes the app keeps disconnecting, so I need to start the process again. So the software needs some work.
  • Currently, it seems that it isn’t available for the U.S. market, only in E.U.

The ketone breathalyzer package comes with an Acetrack device, user guide, charging cable and one extra mouthpiece.

What We Liked

  • Doesn’t need to be recalibrated
  • Feels premium in hand and has a good build quality
  • Compact design and easy to use when on the go

What Can Be Improved

  • No device screen, so you always need a smartphone for readings
  • Takes about a minute to warmup
  • Isn’t available in the U.S.

Best for: Keto dieters in E.U.
App: Android and IOS
Weight: n/a
Battery: Rechargeable
Dimensions: n/a

How Does a Ketone Breath Analyzer Work?

According to keto studies, while on a ketogenic diet, the restriction of carbs leads to the body utilizing fats for fuel.

Acetoacetate can then be converted to the other two ketone bodies, acetone and BHB (b-hydroxybutyrate).

ketonix breath analyzer

Breath ketones (Acetone) are spontaneously released when fat is metabolized into ketone energy. 

  • B-hydroxybutyrate is measured by using blood meters, while acetone diffuses in the lungs and can, therefore, be measured by testing exhaled breath.
  • A ketone breath meter is a device that measures the amount of acetone in your breath.

Unlike other methods, such as urine strips or blood tests, breath ketones levels do not depend on fluid logistics, minerals or vitamins, etc.

The more breath ketones, the more fat is metabolized into energy. Breath samples are non-invasive and can be done many times throughout the day without extra costs. 

This makes your ketogenic diet journey way more enjoyable.

Ketone breath analyzer works like this:

  • You breathe into a tube that measures certain elements on your breath. In this case, acetone—which is also responsible for making your breath stinky in ketosis. 
  • The higher your score, the deeper you are in ketosis and the more successful you may be on the keto diet.

Research has shown that breath acetone is a reliable indicator of ketosis in people who consume low-carb meals. (1) Whether it’s your first time trying out a low-carb diet or you are deeply into a ketogenic diet, a ketone breath meter can be a handy tool.

Breath Analyzer vs. Blood Ketone Meter

Even though blood ketone meters are considered to be the gold standard, there are multiple advantages to using a ketone breath meter instead.

breathalyzer vs blood ketone meter keto

Ease of use

  • Ketone breath meter is the easiest and most convenient to use. Perfect when you cannot pee on a stick or you are on the go. Simply blow some air into the device, and you get accurate results within seconds. 
  • Probably the biggest downside with blood meter is that for every measurement you need to prick your finger. If you don’t like blood then it can be a dealbreaker. Also this process requires quite clean environment.
  • Most breath meters (with a couple of exceptions) are the size of a pen (bulky), so it fits perfectly into your pocket and you can test your breath ketones in a Uber or a Yoga class.


  • With any meter, you must take the total price into account – the price of the meter itself plus any additional fees for continual use.
  • If you go for a blood ketone meter, you’d usually spend about 50-100$ on the starting kit, and then about a dollar per strip for each additional testing. And if you want to test your ketones 2 or 3 times a day, you can see how the total cost can pile up quickly.
  • Now, with breath ketone meters, there is no additional cost. Most of them are usually a bit more expensive than blood ketone meters (about 100-200$, depending on the brand), but you just buy them once and use them basically forever.


  • Blood ketone meters are the most accurate (and most expensive) way to measure ketones. They measure the exact amount of the BHBs in the blood – an exact number reading (mmol/L). 
  • Breath analyzers provide the second most precise ketone readings. Measure the amount of acetone in the breath – range in PPM (parts per million). According to research, measuring breath acetone levels provides a non-invasive tool for monitoring the rate of fat loss in healthy subjects. (2)
  • Urine strips are the third and least effective way to measure ketones. These test strips measure the excess concentration of Acetoacetate in the urine. The issue here is that over time the body adapts to excrete fewer ketones in the urine. Ketone test strips can be useful if it’s your first time doing low carb and you want to see how your body reacts.

Can I Just Use a Cheap Breathalyzer Instead?

In theory, yes, you can. When it comes to alcohol breathalyzers, they have two types of sensors.

  • Cheap breathalyzers have a “semiconductor” sensor, and the more expensive ones use a “fuel conductor” sensor. 
  • And unlike the latter, the semiconductor sensors can’t tell the difference between Acetone and Ethanol (alcohol), which is actually good if you want to test your breath for Acetone.
cheap breathalyzers

Now, considering the price/quality of the device, accuracy-wise, they won’t be even close to the more expensive types of breathalyzers made specifically for Acetone testing.

Cheap breathalyzers can give you a general idea of how much Acetone you have in your breath, but because of the quality, your results will vary a lot.

If it’s your first time doing low carb then you can play around with it. If you are serious about getting quality feedback, we strongly suggest you opt for some of the other options we discuss at the end of the article.

Will I also get in trouble with the police, then?

And if you were just wondering, no, you won’t get in trouble if the police ask you to do a breathalyzer test.

Nowadays, they all use the more expensive types of breathalyzers that use a fuel conductor sensor.

Tips for Measuring Breath Ketone Levels

When and how often should you test your breath ketones?

The advantage of breath meters is that you can use them an infinite amount of times, so you can afford to test them multiple times a day.

But, when testing, you still need to do it with a purpose in mind. You are still on a ketogenic diet and your goal is to stay in ketosis.

  • Choose a time that’s convenient for you and make a routine to test daily, you will be able to compare your results to prior days at the same time and get some good data out of it.
  • If you decide to test in the morning, note that due to the “dawn effect”, ketone levels are lower and blood glucose levels are higher as compared to later in the day. (3) If you, however, choose to test later in the day, the best time would be before you have a meal.
  • Another trick is to see how you are reacting to the foods you are eating. Test once before you have the meal, and then 30, 60, and 120 minutes after eating. This shows what effect the food you eat has on your ketone levels. Also, you can do this same test for your blood glucose levels as well.
ketone breath level readings

Breath acetone ketosis levels

  • Breath acetone can range in concentration from 1 ppm in healthy non-dieting people to 1.250 ppm in diabetic ketoacidosis. In healthy individuals, breath acetone levels can be affected by multiple factors, like dietary macronutrient composition, caloric restriction, exercise, and some other more minor factors.
  • When testing your acetone levels with a breath meter, you will get back a number in PPM (parts per million). The breath value ranges for nutritional ketosis are 4-30 PPM, so you’d want your number to fall somewhere within this range. If you are at 0, you are not in ketosis at all, if you are at 1, 2, or 3, you are in a light state of ketosis, but you would want to try and increase it, so it fits the range.
  • Most of the breath meters nowadays use the PPM metric system, but if yours happens to be in nM (molar basis), the conversion is 1 ppm = 39.7 nM.

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