Your GKI score tells you something that glucose and ketone readings alone can't: whether your body is actually running on fat. It's the ratio between the two that matters, and that single number cuts through the noise of daily fluctuations to show your true metabolic state.
Whether you're doing keto for weight loss, fasting for longevity, or following a therapeutic protocol, this calculator gives you instant clarity. Plug in your glucose and ketone readings, and you'll know exactly where you stand—plus what that number actually means for your goals.
What is GKI?
The Glucose Ketone Index comes from Dr. Thomas Seyfried's cancer research at Boston College. He needed a reliable way to track whether patients were achieving therapeutic ketosis, and he found that the ratio of glucose to ketones was far more stable and meaningful than either number on its own.
Here's the thing most people don't realize: both glucose and ketones bounce around constantly. Your glucose might read 88 mg/dL one morning and 102 mg/dL the next, even if you ate the exact same dinner. Ketones are just as moody. But when you divide one by the other, those fluctuations largely cancel out—and you get a number that actually reflects your metabolic state.
Think of it like this. If your glucose is a bit elevated but your ketones are cranking, you're still burning fat effectively. A single glucose reading would make you think something's wrong. GKI shows you the real picture.
How to Use This Calculator
Step 1: Enter your blood glucose Type in your reading and select your unit—mg/dL if you're in the US, mmol/L if you're elsewhere. The calculator handles the conversion automatically.
Step 2: Enter your blood ketones This needs to be from a blood ketone meter (not urine strips—I'll explain why in a minute). Enter the value in mmol/L.
Step 3: Get your score You'll see your GKI number plus which metabolic zone you're in, from glucose-dominant all the way to deep therapeutic ketosis.
That's it. No manual math required.
Understanding Your GKI Results
GKI Score | What's Happening | The Reality |
|---|---|---|
Above 9 | High Glucose Dominance | You're not in ketosis. Your body is running on glucose, full stop. |
6 – 9 | Moderate Glucose Dominance | Borderline. Maybe trace ketosis, but you're not really burning fat as primary fuel. |
3 – 6 | Low Glucose Dominance | This is the zone. Solid ketosis that most keto dieters are shooting for. |
1 – 3 | Light Therapeutic Ketosis | Deeper ketosis, typically from strict keto plus fasting. Your body's really leaning on fat now. |
Below 1 | Deep Therapeutic Ketosis | Maximum fat-burning. Usually only happens during extended fasts or very strict protocols. |
Here's what I want you to take away: there's no magic "perfect" GKI. Someone doing keto to lose 20 pounds doesn't need the same number as someone on a therapeutic cancer protocol. A GKI of 4 might be exactly right for you. Don't chase someone else's target.
The GKI Formula (It's Simpler Than It Looks)
Once everything's in the same units, you're just dividing:
GKI = Glucose (mmol/L) ÷ Ketones (mmol/L)
If your meter shows glucose in mg/dL, convert it first:
GKI = (Glucose mg/dL ÷ 18) ÷ Ketones mmol/L
Let's Do One Together
Say your morning readings are:
- Blood glucose: 90 mg/dL
- Blood ketones: 1.5 mmol/L
First, convert glucose: 90 ÷ 18 = 5.0 mmol/L Then divide: 5.0 ÷ 1.5 = 3.3 GKI
You're in solid moderate ketosis. Nice.
Real-World GKI Examples
These are actual scenarios you'll encounter—not theoretical textbook numbers.
The Typical Morning Reading (Keto Dieter, Day 14)
Glucose: 85 mg/dL | Ketones: 1.2 mmol/LGKI = (85 ÷ 18) ÷ 1.2 = 3.9You're doing great. This is sustainable, real-world ketosis.
After a Keto Dinner (2 Hours Post-Meal)
Glucose: 115 mg/dL | Ketones: 0.9 mmol/LGKI = (115 ÷ 18) ÷ 0.9 = 7.1Totally normal. Post-meal readings are always higher. Check again in the morning before you worry.
Deep Into a 48-Hour Fast
Glucose: 72 mg/dL | Ketones: 4.2 mmol/LGKI = (72 ÷ 18) ÷ 4.2 = 0.95This is therapeutic-level ketosis. Your body is fully fat-adapted right now.
The "Why Isn't This Working?" Scenario
Glucose: 100 mg/dL | Ketones: 0.3 mmol/LGKI = (100 ÷ 18) ÷ 0.3 = 18.5Here's the thing—your glucose is actually fine. The problem is your ketones are barely registering. You're not producing enough, probably from stress, too much protein, or hidden carbs. Cutting carbs further won't help; you need to figure out what's suppressing ketone production.
This last example is the one I see constantly. People blame carbs when the real issue is elsewhere.
Testing at Home: What You Actually Need
A glucose meter Any standard one works. If you've got one already, use it.
A blood ketone meter This is non-negotiable for GKI. You need a meter that measures beta-hydroxybutyrate from a finger prick—Keto-Mojo, Precision Xtra, or similar. Fair warning: ketone strips are pricey, usually $1-3 each. Budget accordingly.
Why urine strips won't work I know they're cheaper. But urine strips measure acetoacetate, which is a different ketone body that doesn't track reliably with blood levels. Someone can have high blood ketones and barely register on a urine strip, or vice versa. For GKI, you need the blood number. There's no workaround here.
Get Consistent Readings
- Same time every day. Most people test first thing in the morning, fasted. Pick a time and stick with it.
- Wait after eating. If you want a post-meal reading, give it 2-3 hours.
- Wash your hands. Seriously. Even tiny food residue throws off glucose readings. I've seen someone's glucose read 40 points high because they'd peeled an orange.
- Test both within a few minutes. Glucose and ketones change constantly. Don't test glucose at 7am and ketones at 7:30.
Why Your GKI Might Be Higher Than Expected
Diet is the obvious factor, but it's often not the culprit. Here's what else moves the needle:
Stress Cortisol raises blood glucose directly. I've seen people eat zero carbs for a week and still have elevated glucose because they were dealing with work deadlines or family drama. This isn't a willpower failure—it's physiology.
Sleep One bad night can raise your fasting glucose 10-15 points. Chronic poor sleep creates insulin resistance. If your GKI won't budge, look at your sleep before you look at your food.
Too much protein Your body converts excess protein to glucose through gluconeogenesis. Eating a pound of chicken breast in one sitting? That might be your problem.
Exercise timing Intense workouts temporarily spike glucose as your liver dumps glycogen. Don't test immediately after the gym—wait an hour.
Coffee Some people see their glucose jump 10-20 points from black coffee alone. If your fasted readings seem off, try testing before your first cup.
Time of day GKI is usually lowest mid-morning and highest in the evening. That's normal circadian rhythm, not a problem to fix.
Actually Lowering Your GKI
Ordered from "try this first" to "okay, time for serious measures":
The easy wins:
- Push breakfast back an hour or two (longer overnight fast without changing what you eat)
- Audit your sauces, dressings, and "keto" packaged foods for hidden carbs
- Walk for 15-20 minutes after your biggest meal
If you're still stuck:
- Drop protein slightly—aim for 0.7-0.8g per pound of goal body weight instead of 1g+
- Add a tablespoon of MCT oil or coconut oil to directly boost ketone production
- Seriously address sleep (not "I should sleep more" but actually fix it)
For stubborn cases:
- Do a 24-36 hour fast to jumpstart ketone production
- Actively manage stress—whatever that means for you
- Count your actual calories. Some people's bodies simply won't produce high ketones in a significant caloric surplus. It's not a metabolism problem; it's math.
One thing I'll say directly: stop chasing GKI 1.0 unless you have a specific reason. A GKI of 4-5 is plenty for weight loss. Stressing about getting it lower will literally raise it (cortisol, remember?). Hit a reasonable target and then relax.
What GKI Should You Actually Aim For?
Your Goal | Realistic Target | What to Expect |
|---|---|---|
Just eating low-carb | Under 9 | Confirms you're out of glucose-dominant metabolism |
Keto for weight loss | 3 – 6 | Where most successful keto dieters land |
Optimizing metabolic health | 1 – 3 | Requires consistent effort—strict keto plus some fasting |
Therapeutic protocol (Seyfried) | Under 2, often ~1.0 | Medical supervision recommended. This is hard to maintain. |
Extended fasting | Under 1 | Happens naturally after 48+ hours. Don't force it otherwise. |
Is GKI Tracking Right for You?
It makes sense if you're:
- Plateaued on keto and wondering if you're actually in ketosis
- Doing extended fasts and want to verify you're hitting therapeutic levels
- Following a specific metabolic protocol with GKI targets
- The type who likes data and finds numbers motivating
You can probably skip it if you're:
- Casually eating lower carb without strict goals
- Already getting the results you want
- Someone who gets anxious about metrics
Honestly? Most people don't need to track GKI religiously. Weekly or a few times weekly tells you everything you need to know. Daily testing gets expensive and tends to create stress that undermines the whole point.
Keep It in Perspective
GKI is a useful tool, but it's exactly that—a tool. The number on your screen is a snapshot of one moment, not your metabolic destiny.
Meter accuracy varies. Your readings tomorrow might be different even if nothing changed. And a "good" GKI means nothing if you feel terrible, can't sleep, or hate what you're eating.
If you're using GKI for a serious health condition, work with practitioners who understand metabolic therapy. This calculator gives you data, not medical advice.
Track trends. Don't obsess over daily fluctuations. And if your GKI is a bit higher than you'd like but you feel good, have energy, and you're seeing progress—maybe that's okay.
The number serves you. Not the other way around.