Blood Sugar Converter

Convert blood glucose values between mmol/L and mg/dL and interpret common glucose ranges with diagnostic threshold context for fasting and post-meal readings.

Share this calculator

Converted value
99 mg/dL
5.5 mmol/L = 99 mg/dL
Normal (fasting)
Fasting blood glucose in the normal range.
Reference ranges
Contextmmol/Lmg/dL
Fasting — Normal3.9–5.570–99
Fasting — Pre-diabetes5.6–6.9100–125
Fasting — Diabetes≥7.0≥126
2h post-meal — Normal<7.8<140
2h post-meal — Pre-diabetes7.8–11.0140–199
2h post-meal — Diabetes≥11.1≥200

This tool is for educational purposes only. Blood glucose interpretation requires clinical context. Do not make medical decisions based on this result alone.

Also in Diabetes

A1c Calculator Diabetes Risk Calculator Estimated Average Glucose Calculator HOMA-IR Calculator

Health — Medical

Blood Sugar Converter

Blood glucose is reported in mmol/L in the UK, Australia, Canada, and most of Europe, and in mg/dL in the United States and many other countries. Converting between these units and understanding the reference ranges for each context — fasting, post-meal, and random — is the purpose of this tool.

Understanding the units

Both mmol/L (millimoles per litre) and mg/dL (milligrams per decilitre) measure the same thing: the concentration of glucose in blood. To convert mmol/L to mg/dL, multiply by 18.0182. To convert mg/dL to mmol/L, divide by 18.0182. A blood glucose of 5.5 mmol/L equals approximately 99 mg/dL.

The choice of unit is purely conventional and differs by country. Diabetes management devices and laboratory reports use the local standard, which can cause confusion when interpreting readings from international sources, clinical guidelines, or research papers.

Reference ranges and diagnostic thresholds

Fasting blood glucose (measured after an overnight fast of at least 8 hours) below 5.6 mmol/L (100 mg/dL) is considered normal by WHO and ADA criteria. The pre-diabetes range is 5.6–6.9 mmol/L (100–125 mg/dL). A fasting glucose of 7.0 mmol/L (126 mg/dL) or above on two separate occasions meets WHO diagnostic criteria for diabetes.

Post-meal glucose (measured 2 hours after starting a meal) below 7.8 mmol/L (140 mg/dL) is normal. The 2-hour oral glucose tolerance test uses these same thresholds for clinical diagnosis. Random blood glucose of 11.1 mmol/L (200 mg/dL) or above with symptoms of hyperglycaemia is also consistent with a diabetes diagnosis.

Frequently asked questions

Why does my meter show different numbers than my doctor's lab results?

Home glucose meters measure capillary whole blood, while laboratories typically measure venous plasma glucose. Plasma values are approximately 10–15% higher than whole blood values. Most modern meters are calibrated to report plasma-equivalent values, but older meters may report whole-blood values — check your device manual.

 What is a normal blood sugar level?

For a person without diabetes, fasting blood glucose is typically 3.9–5.5 mmol/L (70–99 mg/dL) and rarely exceeds 7.8 mmol/L (140 mg/dL) two hours after a meal. Blood glucose below 3.9 mmol/L (70 mg/dL) is defined as hypoglycaemia.

Related

More from nearby categories

These related calculators come from the same leaf category, nearby sibling categories, or the same top-level topic.

A1c Calculator

Convert HbA1c to estimated average blood glucose and vice versa, with ADA classification, reference ranges, and a three-month average note.

Open calculator

Estimated Average Glucose Calculator

Convert HbA1c into estimated average blood glucose in mmol/L and mg/dL using the ADA ADAG formula, with interpretation and a quick-reference table.

Open calculator

HOMA-IR Calculator

Estimate insulin resistance using fasting insulin and fasting glucose with the HOMA-IR formula, interpretation bands, and clinician escalation guidance.

Open calculator

Calorie Calculator

Estimate BMR, maintenance calories, target intake, and daily macro guidance for weight loss, maintenance, or muscle gain in one practical calorie calculator.

Open calculator

Privacy choices

If you allow analytics, we may use Google Analytics and Microsoft Clarity to better understand how the site is used. Analytics remain off unless you accept.