How to get accurate readings with a breath ketone meter

Breath ketone meters

Breath ketone meters have been around for over 24 months and many buyers have found them incredibly useful, especially for ketosis diet followers, they are much easier than urine dip testing or blood beta ketone testing.

ketone breath meter how to use

Guide to using a breath ketone meter to get reliable results

However there are some inherent issues in using a breath ketone meter and is this article we are going to cover the main problems, new users of breath ketone meters experience when transferring to breath ketone testing.

What does a breath ketone meter measure

The first and major issue is that breath ketone meters do not actually measure beta ketone in breath.

Instead they measure a by product acetone to estimate the underlying beta ketone, using a standard calculation. Now acetone is a very good chemical indicator for measuring ketosis, the problem is that acetone is not 100% specific to ketone levels, and the other big problem is that multiple air borne chemicals can be detected by the ketone meter sensor, and interpreted as acetone.

Substances on your breath or in the air can cause the ketone breath meter to give erratic results

The biggest one of these is alcohol. If you have any residual alcohol in your mouth or breath the ketone meter will read high or be off the scale (E-01) This does mean you cannot drink while using a breath ketone meter, and may actually damage or break the sensor if you do. This includes mouth wash remember.

Next on the hit list for wild and erratic results are volatile esters. If you take a breath in and smell something, that's a volatile ester, and the breath ketone meter will detect it too. Commonly these come from perfumes or deodorants, household cleaning products or cooking smells. To get accurate and consistent results you need to avoid these.

Timing is crucial with a breath ketone meter

As in comedy, timing is critical when it comes to getting useful information from your series of breath ketone test results, so be consistent in when you test with the ketone breathalyser. Ketone levels will be highest after periods of long fasting, for this reason most users tend to test first thing in the morning to get a baseline of their peak ketone levels.

Breath technique is very important with a ketone breath meter

Breath technique is all important. Most breath ketone meters require a 10 second deep lung breath sample, and a lot of people find this hard to manage, having to stop mid sample, inhale and resume the blow resulting in wildly erratic readings.

The correct technique for sampling is not to deeply inhale and hold the breath before sampling, but just to breath normally, inhaling in good time to start a long and slow, controlled blow for a full 10 seconds. Controlling the volume in a slow exhale is the trick, not to blow fast or hard, just gently out through the meter.

FAQ regarding using breath ketone meters

Here are the most commonly asked questions regarding using ketone breath meters. If you have a question that is not answered here about using a ketone breath meter that you have purchased from us, then please send us an e-mail and we will answer it.

Is a breath ketone meter ever going to give you the accuracy of a blood ketone meter?


A blood ketone meters is always going to give you more reliable results as there because of the issues listed above. A breath ketone meter is more of a guide as to whether you are in ketosis or not.

Is a breath ketone meter going to give you a good indication of your ketosis levels ?


A breath ketone meter is more of a guide as to whether you are in ketosis or not.

Will sequential breath tests vary by +/-15% ?


Is a breath ketone meter as accurate as a blood ketone meter ?

If you want an easy non invasive pocket ketone test to monitor your diet these breath ketone meters are great.

If you expect a scientifically accurate ketone testing meter, and will be driven mad by the variance in ketone test results, and if you insist on accuracy then buy a blood ketone meter as they are far more accurate way to measure your ketone levels at home.  

Author Dr Mike Garside

Medical Director Access Diagnostic Tests UK Limited

Breath ketone meter information page last updated 25th August 2022

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