Check what a blood sugar reading means. This free tool shows which standard reference range your fasting, post-meal, random or HbA1c result falls into — informational only, not a diagnosis.
⚠ Informational only — this is not a diagnosis. Blood sugar varies with food, activity, stress and illness, and only a doctor can diagnose diabetes or related conditions using proper testing. Never start, stop or change treatment based on this tool.
Your reading
mg/dL
For HbA1c, enter a percentage (e.g. 5.5). Reference ranges follow common ADA guidance for non-pregnant adults.
Reference category
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Choose a test type and enter a reading
Your reading
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Test type
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Normal range
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Basis
ADA reference
Reference ranges are general and for non-pregnant adults; pregnancy, children and some conditions use different targets. Always confirm with a healthcare professional.
Use this free blood sugar level checker to see which reference category a glucose reading falls into. Choose the test type, enter your value, and the tool shows the standard range — for information only.
Important: this checker is informational only and is not a diagnosis. Blood sugar changes constantly with food, activity, stress and illness, and diabetes can only be diagnosed by a doctor using proper testing. Never start, stop or adjust any treatment based on this tool.
What this blood sugar checker shows you
A blood sugar level checker compares a glucose reading against common reference ranges. Pick whether the reading is fasting, two hours after eating, random, or an HbA1c (three-month average), enter the number, and it shows the general category — normal, prediabetes range or diabetes range — using widely cited ADA guidance for non-pregnant adults.
Blood sugar reference ranges (adults)
Test
Normal
Prediabetes
Diabetes
Fasting
70–99 mg/dL
100–125
126+
2 hrs after eating
Under 140
140–199
200+
HbA1c
Below 5.7%
5.7–6.4%
6.5%+
To convert units: 1 mmol/L ≈ 18 mg/dL. So 5.5 mmol/L is about 99 mg/dL.
What the numbers mean
Fasting: measured after 8+ hours without food, often first thing in the morning.
Post-meal (2 hours): shows how your body handles a meal.
Random: taken at any time, regardless of eating.
HbA1c: reflects average blood sugar over the previous ~3 months.
How to use the blood sugar checker
Select the test type that matches your reading.
Enter the value (and choose mg/dL or mmol/L for glucose).
Read the category. It updates instantly with the normal range for context.
Blood sugar terms glossary
Term
What it means
Fasting glucose
Blood sugar after not eating for 8+ hours.
HbA1c
Average blood sugar over about three months.
Prediabetes
Higher-than-normal levels that aren’t yet diabetes.
mg/dL & mmol/L
Two units for measuring glucose.
Blood Sugar FAQ
What is a normal blood sugar level?
For non-pregnant adults, a fasting reading of 70–99 mg/dL is typically considered normal, under 140 mg/dL two hours after eating, and an HbA1c below 5.7%. These are general references, not a diagnosis.
What level is considered prediabetes?
Commonly, a fasting reading of 100–125 mg/dL, a 2-hour reading of 140–199 mg/dL, or an HbA1c of 5.7–6.4% falls in the prediabetes range. A doctor confirms this with proper testing.
What blood sugar level indicates diabetes?
Reference thresholds are a fasting reading of 126 mg/dL or higher, a 2-hour reading of 200+ mg/dL, or an HbA1c of 6.5% or above. Only a healthcare professional can diagnose diabetes, usually with repeat testing.
How do I convert mg/dL to mmol/L?
Divide mg/dL by about 18 to get mmol/L (or multiply mmol/L by 18 for mg/dL). For example, 99 mg/dL is roughly 5.5 mmol/L. This checker handles both units.
Can one reading tell me if I have diabetes?
No. Blood sugar fluctuates throughout the day, and diagnosis requires specific tests, often repeated, interpreted by a clinician. Use this tool only to understand ranges, not to self-diagnose.
Is the blood sugar checker free to use?
Yes, this blood sugar level checker is completely free, needs no sign-up, and gives instant results in your browser. It is informational only and not a substitute for medical advice.
