GMI and Time in Range Calculator
Paste a list of glucose readings, or enter your average, to get your Glucose Management Indicator, time in range and glucose variability, compared with the international CGM targets. All calculations run in your browser and nothing is stored.
Your data is not stored or sent to the server. All calculations are performed locally in your browser.
Paste readings separated by commas, spaces or new lines, up to 1000. A CGM export over 14 days or more gives the most meaningful result.
Paste your readings or enter an average glucose to see your GMI and time in range.
Glucose ranges
The five ranges used in CGM reports.
| Range | mg/dL | mmol/L |
|---|---|---|
| Very low | Below 54 | Below 3.0 |
| Low | 54–69 | 3.0–3.8 |
| In range | 70–180 | 3.9–10.0 |
| High | 181–250 | 10.1–13.9 |
| Very high | Above 250 | Above 13.9 |
Time in range targets
International consensus targets for most adults with type 1 or type 2 diabetes.
| Measure | Goal |
|---|---|
| Time in range (70–180) | More than 70% |
| Time below 70 | Less than 4% |
| Time below 54 | Less than 1% |
| Time above 180 | Less than 25% |
| Time above 250 | Less than 5% |
| Glucose variability (CV) | 36% or less |
How it's calculated
GMI (%) = 3.31 + 0.02392 × mean glucose (mg/dL)CV (%) = standard deviation ÷ mean × 100Time in range = readings in 70–180 mg/dL ÷ all readings × 100Sources: Bergenstal et al., Diabetes Care 2018 (GMI); Battelino et al., Diabetes Care 2019 (Time in Range consensus)
Last reviewed
Frequently asked questions
What is the Glucose Management Indicator (GMI)?
GMI estimates what your A1c would be from your average glucose, using a formula derived from continuous glucose monitor (CGM) data. It replaced the term 'estimated A1c' in CGM reports in 2018 because it can differ from a lab A1c.
Why is my GMI different from my lab A1c?
A lab A1c is also affected by how long your red blood cells live and other individual factors, so the two often differ by a few tenths of a percent or more. Neither is wrong: they measure different things, and the gap tends to be consistent for each person.
What is time in range?
Time in range (TIR) is the share of readings between 70 and 180 mg/dL (3.9 to 10.0 mmol/L). The international consensus suggests most adults with diabetes aim for more than 70% of the time in range, which is roughly equivalent to an A1c of about 7%.
What are the time in range targets?
For most adults with type 1 or type 2 diabetes: more than 70% in range, less than 4% below 70 mg/dL, less than 1% below 54 mg/dL, less than 25% above 180 mg/dL and less than 5% above 250 mg/dL. Targets are more cautious for older or high-risk adults and differ in pregnancy.
What does the CV (coefficient of variation) mean?
CV is the standard deviation of your readings divided by the mean, as a percentage. It measures how much your glucose swings. A CV of 36% or less is considered stable; higher values are linked with more frequent lows.
How much data do I need?
The consensus recommends at least 14 days of CGM data with the sensor worn at least 70% of the time. Finger-prick readings can still show a pattern, but they miss the times you don't test, so treat the result as a rough guide.
Related calculators
All diabetes tools- A1c CalculatorConvert an HbA1c result to estimated average glucose, or estimate A1c from your average blood sugar.
- Blood Sugar ConverterConvert blood glucose between mg/dL and mmol/L and see where a reading sits against standard ranges.
- BMI CalculatorCalculate your Body Mass Index (BMI) to assess your weight status and health risk categories.