GKI Calculator — Glucose Ketone Index & Autophagy Timeline.
Free online GKI tracker. Map your fasting hours to the cellular stage you're in, then (optionally) compute your exact Glucose-Ketone Index from blood glucose and ketone readings and read it on the GKI chart.
Insulin drops, glucagon rises.
Liver glycogen runs low. AMPK activates in response to nutrient scarcity. Autophagy pathways begin to engage.
Medical Disclaimer
Extended fasting and ketogenic protocols carry real medical risk for people with diabetes, eating disorder history, pregnancy, or on certain medications. Consult a physician before fasts beyond 24 hours.
GKI Formula
The Glucose-Ketone Index is a dimensionless ratio of blood glucose to blood beta-hydroxybutyrate, both expressed in mmol/L.
Lower GKI means deeper ketosis. The formula was published by Meidenbauer, Mukherjee, and Seyfried (2015) as a single metric to track therapeutic ketogenic state in oncology research.
How to Calculate GKI
The Glucose-Ketone Index reduces two metabolic markers to a single number. It was originally proposed by Thomas Seyfried's group to track patients on therapeutic ketogenic diets.
- 01Convert glucose units. If glucose is in mg/dL (US standard), divide by 18.016 to convert to mmol/L. If you already report in mmol/L (rest of the world), skip this step.
- 02Compute GKI. GKI = glucose (mmol/L) / ketones (mmol/L). Both have to be in the same units for the ratio to be dimensionless.
- 03Locate band. GKI < 1 = peak therapeutic. 1–3 = high therapeutic. 3–6 = moderate. 6–9 = mild. >9 = no ketosis.
- 04Map fasting hours. Independently of GKI, the calculator maps elapsed fasting time to the four canonical autophagy stages: fed (0–12h), glycogen depletion (12–24h), active autophagy (24–48h), peak (48–72h).
Worked Example
GKI Levels Chart & Ranges
The GKI scale runs from below 1 (deepest therapeutic ketosis) to above 9 (no ketosis). A lower GKI means deeper ketosis and more autophagy. Use this GKI chart to read what a given level or range means and what a “good GKI” looks like for your goal.
| GKI Range | Level | What it means |
|---|---|---|
| < 1 | Peak Therapeutic · Maximum Autophagy | Extended-fast territory. Medical supervision recommended. |
| 1–2.999 | High Therapeutic Ketosis · Deep Autophagy | Used in clinical fasting protocols. |
| 3–5.999 | Moderate Ketosis · Active Fat Burn | Reliable fat oxidation. Autophagy engaging. |
| 6–9 | Mild Ketosis · Low Autophagy | Early ketogenic adaptation. |
| > 9 | No Ketosis | Baseline metabolic state. No autophagy benefit. |
For everyday metabolic health and lifestyle keto, a GKI of 3–6 is a sensible target. Therapeutic protocols (clinical fasting, epilepsy, oncology research) aim for GKI 1–3, and supervised extended fasts can push below 1. Above 9, you are not in therapeutic ketosis.
Frequently Asked Questions
What is the Glucose-Ketone Index (GKI)?+
GKI is the ratio of blood glucose (in mmol/L) to blood ketones (also in mmol/L). It is used in clinical research and metabolic therapy as a single number that summarises how deeply someone is in ketosis. A lower GKI means deeper ketosis.
What is the GKI formula?+
GKI = glucose (mmol/L) ÷ ketones (mmol/L). If your glucose meter reports in mg/dL (the US standard), first divide by 18.016 to convert to mmol/L. The result is a dimensionless ratio — lower numbers mean deeper ketosis.
How do I calculate GKI from a glucose meter?+
Three steps: (1) measure blood glucose (mg/dL or mmol/L) and blood beta-hydroxybutyrate (mmol/L); (2) if glucose is mg/dL, divide by 18.016; (3) divide that glucose value by the ketone value. Match the band on the GKI chart to read your state.
What is a good GKI for autophagy?+
Most research links GKI < 3 with active autophagy, GKI < 1 with peak cellular recycling. GKI > 9 means you are not in therapeutic ketosis. The exact target depends on protocol — Thomas Seyfried's cancer research targets GKI 1–2.
What is a good GKI overall?+
For metabolic health and lifestyle keto, GKI 3–6 is a comfortable target. For deep therapeutic ketosis (clinical fasting, epilepsy, oncology protocols), the target is GKI 1–3. GKI < 1 is extreme territory typically only seen during extended supervised fasts.
What are the GKI ranges and levels?+
The GKI scale has five bands: GKI > 9 = no ketosis (baseline); 6–9 = mild ketosis, low autophagy; 3–6 = moderate ketosis, active fat burn; 1–3 = high therapeutic ketosis, deep autophagy; and < 1 = peak therapeutic ketosis, maximum autophagy. A lower GKI level means deeper ketosis.
What is the GKI scale?+
The GKI scale is the dimensionless 0-to-9+ range used to read your Glucose-Ketone Index. Unlike a fixed chart of normal ranges, lower is "better" for ketosis: most lifestyle keto sits at 3–6, therapeutic protocols target 1–3, and extended supervised fasts can reach below 1. Above 9 you are not in ketosis.
How do I track GKI daily?+
Test under standardized conditions: same time of day (fasted, on waking is most reliable), same finger, same meter. Log glucose, ketones, and the resulting GKI; the trend across days matters more than any single reading. This calculator saves your last entry in localStorage so you can return.
When should I measure GKI — what time of day, and how long after a meal?+
The most reproducible reading is first thing in the morning, fasted, before coffee or exercise — that removes the food and activity noise. If you want a post-meal reading instead, wait at least 3 hours (ideally 4+) after eating, since a meal transiently raises glucose and lowers ketones and can distort the ratio. The single rule that matters most is consistency: test at the same time under the same conditions every day so the day-to-day trend is comparable.
Is GKI useful for weight loss?+
GKI tracks depth of ketosis, not fat loss directly — you can be in deep ketosis and still not lose weight if you are in a calorie surplus. Its usefulness for weight loss is as a compliance signal: a GKI in the 3–6 band confirms you are actually in the fat-burning ketosis you are aiming for, rather than assuming it. You do not need the very low therapeutic GKI (1–2) used in clinical protocols to lose fat; a sustainable 3–6 while in a modest calorie deficit is what drives body-composition change.
Can I use this as a ketone calculator?+
Yes — if you only enter blood ketones (BHB mmol/L) without glucose, the tool still shows the autophagy timeline. With both glucose and ketones, it computes the full GKI and maps your reading to the chart bands.
How many hours of fasting until autophagy starts?+
Autophagy is a gradient, not a switch. AMPK signalling and early autophagy markers appear around 16–18 hours of fasting. Deeper, more therapeutic autophagy ramps up after 24 hours, and peaks around 48–72 hours.
Do I need glucose and ketone meters to use this tool?+
No. If you only know your fasting hours, the tool maps you to the autophagy stage. If you also have a glucose and ketone meter, you can additionally compute your exact GKI for more precise tracking.
Why mg/dL versus mmol/L for glucose?+
The US standard reports glucose in mg/dL, while most of the world uses mmol/L. The GKI formula requires mmol/L, so we divide US-style readings by 18.016 (the molar mass conversion factor for glucose) before computing.
Is extended fasting safe?+
For most healthy adults, fasts up to 24 hours are safe. Fasts beyond 48 hours, anyone with diabetes, anyone on medication, pregnant women, or those with eating-disorder history should only fast under medical supervision.
What GKI measures.
The Glucose-Ketone Index is the ratio of blood glucose to blood beta-hydroxybutyrate, both expressed in millimoles per liter: GKI = glucose / ketones. A US glucose reading in mg/dL must be divided by 18.016 to convert. The lower the number, the more your metabolism has shifted from glucose-burning toward fat- and ketone-burning.
It was developed by Thomas Seyfried and Joshua Meidenbauer in oncology research as a single, dose-responsive metric for the depth of a therapeutic ketogenic state — more informative than either glucose or ketones in isolation, because either can fluctuate without reflecting overall metabolic state.
How to read the bands.
GKI > 9: standard mixed-fuel metabolism. GKI 6–9: light ketosis, the zone most low-carb dieters live in. GKI 3–6: moderate therapeutic ketosis, the band targeted for epilepsy management and where most metabolic-health gains accrue. GKI 1–3: deep therapeutic ketosis, the band used in oncology and neurology protocols. GKI < 1: extreme — usually only achieved under medical supervision with extended fasting or strict therapeutic diets.
Clinical-grade ketogenic protocols (epilepsy, glioma trials) target GKI under 2 sustained for weeks to months. Lifestyle ketosis aiming at metabolic health, fat loss, or mental clarity does not require this depth and is comfortably effective at GKI 3–6.
Fasting and autophagy — what the timing means.
0–12 hours post-meal: fed state, glycogen and circulating glucose dominate. 12–24 hours: glycogen depletes, the body shifts toward fat oxidation, and ketones begin to rise. 24–48 hours: ketones become a major fuel; autophagy markers measurably increase in animal models, and mTOR pathway suppression intensifies. 48–72 hours: deepest autophagy state in the literature, plus the largest growth hormone surge.
The autophagy timing in this tool is drawn from rodent and indirect human data — direct measurement of cellular autophagy in living humans is technically difficult, so exact hour thresholds carry uncertainty. Mizushima’s 2008 Nature review remains the standard summary of how fasting and nutrient deprivation activate autophagy mechanistically.
Lifestyle vs clinical use — important distinction.
Therapeutic ketogenic protocols for refractory epilepsy, certain brain cancers, or insulin-resistance reversal should be run under physician and dietitian supervision — they require electrolyte monitoring, attention to drug interactions, and structured macronutrient ratios. This calculator is a tracking tool, not a medical protocol. If you have type 1 diabetes or are on SGLT2 inhibitors, the risk of euglycemic ketoacidosis makes self-directed deep ketosis unsafe without supervision.
- Meidenbauer JJ, Mukherjee P, Seyfried TN. (2015). The glucose ketone index calculator: a simple tool to monitor therapeutic efficacy for metabolic management of brain cancer. Nutr Metab (Lond), 12:12.
- Mizushima N, Levine B, Cuervo AM, Klionsky DJ. (2008). Autophagy fights disease through cellular self-digestion. Nature, 451(7182), 1069–1075.
- Anton SD, Moehl K, Donahoo WT, et al. (2018). Flipping the metabolic switch: understanding and applying the health benefits of fasting. Obesity (Silver Spring), 26(2), 254–268.
Your glucose-ketone index is downstream of your meals. The blueprint covers the metabolic-eating side.
Get the guide →For education, not medical advice. Results are estimates, not a diagnosis — discuss any abnormal value or health concern with a qualified clinician.
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