Ketone Meter – Blood vs Breath vs Strips

Last Updated on: 16th November 2023, 07:58 pm

The theory behind a keto diet is simple – get into ketosis and your body will magically improve, giving you the benefits of everything from weight loss to blood sugar levels, epilepsy to neurological disorders, certain types of cancer treatments, and of course, weight loss.123

This raises an obvious question: how do you know when you are in ketosis?

After all, it’s not something you can see (other than the fact you should be losing weight!).

There are three main ways of ketone testing you can do at home – using test strips (urine), a breath meter or a blood ketone test.

So which one is right for you?

Read on for everything you need to look for in your next ketone meter – blood vs breath vs strips.

Why measure ketones?

There are a couple of reasons you might want to test for ketones – either you’re following a keto diet and want to make sure you’re in ketosis, or you have a doctor’s recommendation to check your levels because you have Type 1 Diabetes.

In this article, we’re focusing on the first option.

Why aim for ketosis?

As I said above, keto diets have been shown to be effective for everything from helping to lose weight (and to do it quickly) to helping with health issues such as blood sugar. But if you ask a random person about keto, weight loss comes up over and over again.

Scientists say the same thing:

One diet regimen that has proven to be very effective for rapid weight loss is a very low-carbohydrate and high-fat ketogenic diet.4

The reason scientists like it so much is that majority of chronic diseases suffered by people with diabetes, hypertension, and heart disease are largely related to obesity which is usually a product of an unhealthy lifestyle and poor dietary habits.

Do the inches on your outside match the levels in your inside? Measuring ketone levels is a scientific way to validate what you feel - weight loss from ketones

How do you know you’re in ketosis?

Following the instructions for a diet, you see in a book or on the internet is all very well, but how do you know it’s working? If you read the research, it’s all about knowing your blood ketone levels.

N0w that’s fine to say, but how do you know what level you’re at? You can’t see how many ketones are in a drop of blood.

The answer? Well, there are two answers

  • You can rely on feel – are you losing weight, and have lots of energy, mental clarity and all the good stuff that comes with keto? If you are in this state, you can be pretty sure you’re in ketosis and your blood ketone level is fine
  • You can test for it – let’s face it, while many of us are happy to rely on a feeling, there’s nothing like a tool or gadget to boost your confidence. And where there’s a need, there’s a product to fit your need.

Ketone Testing

Can I test my ketone levels at home?

Technology has come a long way and having the equipment to do a test at home makes things much more convenient – and if it’s not quite “medical grade” testing, it’s close enough for the needs of a dieter.

There are several ways to get ketone testing done, depending on whether you need it. If you’re just curious, it’s easiest to pick up a kit you can use at home. Of course, if there’s a medical reason you need testing, a doctor or medical professional is always the best option.

If you do decide to start at home, there are three main types of kits to consider: test strips, blood meters and breath meters.

Ketone test strips

Cheap and easy to use, ketone test strips are the entry-level option for getting started on testing your ketone levels. They test based on ketones in your urine (not your blood) and are easier to use than a glucose blood meter or breath analyzer monitor. There’s also the advantage that you don’t have to worry about needles.

If you’re just getting started in your keto journey, they can help you work out what foods get you into ketosis – and what foods kick you out.

There are some downsides to the strips.

  1. The obvious one is that you need to get urine on the strip to get an accurate reading. Not technically difficult, but not for the squeamish either!
  2. Related to this, not all of us have the ability to produce urine on demand. You can only do the test when your body is ready.
  3. Secondly, you have to take a reading based on the colour of the strip and compare that to the colours on the manufacturer’s scale. This can be a bit of a judgement call at times – a bit like working out ph levels from those swimming pool test strips, at times it can feel like more of an art than a science.

Take a look at the range of Ketone Test Strips.

Ketone meters

Ketone meters are a great option if you’re looking for something a little more sophisticated than a test strip. Because they come with a display rather than making you read from a scale, you always know exactly where you are with your ketone test and can compare one day (or afternoon) with the next to track your progress.

Even better, some of them even connect to your phone, meaning you can track progress without having to physically write anything down – a great way to help with your keto diet motivation.

Again, there are some decisions to be made when it comes to what you want your ketone testing for. Do you want to test blood ketone levels? Blood glucose levels? And what do you want to use to test them? Do you want to squeeze out a drop of blood each time? Urine? Your breath?

Below is a quick run-through of your options to help you decide which meter will deliver the right test is right for you.

Ketone Breath Test Meters

As the name suggests, ketone breath meters use the air you breathe out as a way of testing whether you are in ketosis. They don’t measure ketones, instead, they usually measure the acetone concentration.

Acteone is produced when fat is metabolised – the more fat that’s being burnt, the higher the level of acetone.

Numerous studies have shown that acetone levels are a good marker for being in ketosis. THey have correlated acetone levels with fasting blood glucose levels, ketones in the blood and urine, LDL-C, creatinine, and blood urea nitrogen.5

Are breath ketone meters accurate?

Breath ketone meters fall somewhere between strips and blood testing. While they’re more precise than strips, they’re better suited to show how likely you are in ketosis than to deliver any sort of medical-grade result.

That said, remember breath meters are used in some important checks – testing for breath alcohol levels is one good example – so they are accurate, and getting better as the technology improves.

More importantly, breath meters are the quickest, easiest and most convenient way of testing for ketosis.

What’s a good reading on a ketone breath meter?

Breath acetone levels are measured in parts per million (PPM). For a healthy person not in ketosis, the level is usually below 2. By following a ketogenic diet, you should be able to get your breath levels up to around 10-39. Remember that it takes time to get into ketosis – two to five days is not unusual.

A rough guide to what each level means is below.

  • 0.0-1.9ppm – Normal levels, no ketosis
  • 2.0-3.9ppm – Early Stage Ketosis – the body is burning more fat than usual
  • 4.0-9.9ppm – Light Ketosis – the body is burning fat at a low rate)
  • 10-39ppm – Stable Fat Burning Zone – congratulations, you are in the keto zone for fat burning
  • 40-59ppm – High Ketosis – take care at this level
  • 60-99ppm – Ketoacidosis – your body is breaking down fat too quickly

Take a look at the range of Ketone Breath Meters.

Ketone Blood Test Meters

Just the mention of blood is enough to put some people off using these kits. But they are more accurate than the strips or breath, so if you want the best possible home ketone testing, blood ketone testing is what you should be looking at.

These tools test for the level of ketones in your blood, giving you a direct report on the state of your fast.

And the good news is that they don’t need a lot of blood for testing. Typically the level is 0.5 microlitres, so literally less than a drop of blood. The blood is taken through a small lancet, (or needle) which is pressed against the finger to draw blood. The blood is then pressed against a test strip and inserted into the testing device, which will give you a reading on blood ketones within a few seconds.

It’s quick and painless

Are breath ketone meters accurate?

Yes. If you’re after a test with maximum precision, whether at home or in the hospital, blood tests are the gold standard. That said, you do get what you pay for, and typically the more expensive devices give a more accurate result.

What’s a good reading on a ketone blood meter?

Most researchers believe that ketosis begins at molecular concentration levels of 0.5 mmol/L.6 This is a “light” or entry level for ketosis, you are in the beginnings of ketosis, but you will get the full benefits when you enter the next stage.

  • 0.5 mmol/L – congratulations, you have entered ketosis
  • 1-3 mmol/L – the optimal keto blood zone
  • 3-5 mmol/L – possible benefits for certain medical conditions, but should not be attempted without medical advice
  • 20 mmol/L – this is a dangerous level, indicating ketoacidosis

The good news is that the blood test meters come with colour-coded guides to make all this easy.

Take a look at the range of Ketone Blood Meters.

Choosing your ketone meter – blood vs breath vs strips

Which one is right for you?

We’ve covered a lot of ground in the search for the perfect ketone test meter, so here’s a quick table summary.

Ketone Blood meterBreath Test MeterKetone Test Strips
MethodBlood (through a lancet/needle)BreathTest Strips (Urine)
Pain LevelMinorNoneNone
Ongoing costModerateNoneModerate-Low
More informationKetone Blood MeterKetone Breath MeterKetone Test Strips

A final note on accuracy

As I mentioned above, the testing methods we’ve discussed above have different levels of accuracy, but they all provide enough to give you an idea of, firstly, whether you’re burning more fat than usual, and secondly, if you’ve successfully made it to ketosis.

But beware. One thing I’ve heard a lot from people using these tests is that they “don’t work”, but often the kits are fine, the reason they are showing a negative result is just that the person isn’t in ketosis!

There are some common reasons ketone levels can fall:

  • Using creamer or milk in coffee. This is a sure way to drop out of ketosis.
  • Eating not enough or too much protein.
  • Eating the wrong kind of fruit – only a couple of bites of non-allowed fruit will take you right out of ketosis.
  • Expecting to go into ketosis immediately – it usually takes several days of the right fat, protein, and low-carb combination to get your body to generate high ketone levels.
  • Assuming because they have lost weight they are in ketosis. Your NOT! You can lose weight without reaching ketosis BUT once you reach the level of ketosis the weight drops off VERY FAST!!! You also start losing belly fat (visceral fat) and inches much faster!!!
  1. The ketogenic diet for the treatment of childhood epilepsy: a randomised controlled trial []
  2. Exogenous Ketones and Lactate as a Potential Therapeutic Intervention for Brain Injury and Neurodegenerative Conditions []
  3. Nutritional Status at Diagnosis as Predictor of Survival from Childhood Cancer: A Review of the Literature []
  4. Masood W, Annamaraju P, Uppaluri KR. Ketogenic Diet. [Updated 2022 Jun 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. []
  5. Breath Ketone Testing: A New Biomarker for Diagnosis and Therapeutic Monitoring of Diabetic Ketosis []
  6. Nutritional Ketosis for Weight Management and Reversal of Metabolic Syndrome []