Free blood sugar and insulin resistance calculators
Eight calculators for the numbers that actually describe how your body handles carbohydrate — the glycemic load of a real meal, the indices your lab report gives you, and the conversions nobody should have to do by hand.
The calculators
- Glycemic load of a meal Add foods and grams, get the GL of the whole plate and its weighted glycemic index.
- HOMA-IR and QUICKI Fasting glucose plus fasting insulin, in either unit, with the bands and their caveats.
- Risk test (no blood test) Eight validated questions that estimate your ten-year risk of type 2 diabetes.
- TyG index Insulin resistance from triglycerides and glucose, when fasting insulin is unavailable.
- Waist-to-height ratio Two measurements, the NICE boundaries, and why this beats BMI for metabolic risk.
- BMI The WHO bands, and why BMI is the wrong tool for spotting insulin resistance.
- HbA1c to average glucose HbA1c in % or mmol/mol, converted to estimated average glucose in both units.
- mg/dL ↔ mmol/L Convert a blood sugar reading between the two units, with the reference ranges.
Why a calculator and not another article
Most pages about the glycemic index explain the concept and then leave you to do the arithmetic. That is backwards. The concept takes a paragraph; the arithmetic is where people get stuck, because glycemic load depends on how much of a food you actually eat, and because half the world reports blood sugar in mg/dL and the other half in mmol/L.
Every calculator here does one job, shows the formula it used with your own numbers substituted into it, and prints the reference ranges next to the result with the body that published them. Nothing is hidden behind a sign-up, and the reference ranges are on the page even before you type anything — that is usually the real question anyway.
Which one you probably want
- You are looking at a plate of food. Use the glycemic load calculator. It searches the same food database as our food records and totals the load of the whole meal, not one ingredient.
- You are holding a lab report. HOMA-IR if it lists fasting insulin, TyG if it lists triglycerides but no insulin, HbA1c to average glucose if you want to know what your HbA1c would look like on a meter.
- You have no bloods at all. The risk test uses a tape measure and eight questions, and the waist-to-height ratio uses two measurements.
- You are converting a number someone quoted you. mg/dL and mmol/L.
Where the numbers come from
Reference ranges are quoted from the bodies that set them: the American Diabetes Association for HbA1c and fasting glucose, the World Health Organization for BMI, NICE for waist-to-height ratio, the University of Sydney's Glycemic Index Foundation for the glycemic index and load bands, and the original papers for HOMA-IR, QUICKI, TyG and the Finnish Diabetes Risk Score. Each page names its source under the scale and links to it.
Where the literature does not agree, the page says so rather than picking a number and pretending. HOMA-IR is the clearest case: there is no internationally agreed cut-off, and your laboratory's own reference range beats anything on this site.
Frequently asked questions
Are these calculators really free?
Yes. There is no sign-up, no email wall and no trial. The calculators run in your browser, so the numbers you type are not sent anywhere.
Can I share a result with someone?
Yes. When you calculate, the values you entered are written into the page address, so copying the link from the address bar sends the other person the same result.
Do these replace a blood test?
No. The risk test and the body measurements estimate risk without any blood work, and that is genuinely useful, but they estimate. HOMA-IR, TyG and HbA1c all need real laboratory values as input.
Which single number matters most for insulin resistance?
If you can only have one, fasting insulin combined with fasting glucose — that is HOMA-IR. If you cannot get fasting insulin measured, the TyG index uses triglycerides instead, and the waist-to-height ratio needs nothing but a tape measure.
This calculator is educational and is not a diagnosis. It cannot replace a blood test or a conversation with your doctor. If a result worries you, or if you have symptoms, take the numbers to a clinician rather than acting on them alone.