What is the conversion factor between mg/dL and mmol/L?

The exact factor is 18.0182. To convert mg/dL to mmol/L, divide by 18.0182. To convert mmol/L to mg/dL, multiply by 18.0182. Many sources round this to 18, which introduces a small error at high values.

What is a normal fasting blood glucose level?

Normal fasting glucose is below 100 mg/dL (5.6 mmol/L). Values from 100–125 mg/dL (5.6–6.9 mmol/L) indicate prediabetes. A fasting reading of 126 mg/dL (7.0 mmol/L) or higher on two separate tests meets the ADA diagnostic criterion for diabetes.

What is a normal postprandial (2-hour) glucose?

Two hours after eating, glucose below 140 mg/dL (7.8 mmol/L) is normal. Values of 140–199 mg/dL (7.8–11.0 mmol/L) suggest impaired glucose tolerance (prediabetes). At or above 200 mg/dL (11.1 mmol/L) is consistent with diabetes.

How does blood glucose relate to HbA1c (A1C)?

A1C reflects the average blood glucose over roughly 3 months. An A1C of 5.7% correlates to about 117 mg/dL (6.5 mmol/L) average; 6.5% to about 140 mg/dL (7.8 mmol/L); and 7.0% to about 154 mg/dL (8.5 mmol/L). The table on this page shows common A1C-to-average-glucose mappings.

Why do the US and most other countries use different units?

The US adopted mg/dL (milligrams per deciliter) in the early 20th century. Most other countries later standardized on mmol/L (millimoles per liter) as the SI unit. Both measure the same quantity; the difference is purely the unit system used.

Glucose mg/dL to mmol/L Converter

Name: Glucose mg/dL to mmol/L Converter
Availability: InStock
Author: Nham Vu

Instantly convert blood glucose between mg/dL (US) and mmol/L (international) and see where your reading falls in clinical reference ranges.

Enter Blood Glucose Value

mg/dL (US, UK older devices)

mg/dL

mmol/L (international standard)

mmol/L

Converted Value

Enter a value on the left to see the conversion.

Clinical Reference Ranges (ADA Guidelines)

Category	mg/dL	mmol/L
Fasting Glucose
Normal	< 100	< 5.6
Prediabetes (IFG)	100 – 125	5.6 – 6.9
Diabetes	≥ 126	≥ 7.0
2-Hour Postprandial
Normal	< 140	< 7.8
Prediabetes (IGT)	140 – 199	7.8 – 11.0
Diabetes	≥ 200	≥ 11.1

Estimated Average Glucose by A1C

A1C (%)	Avg mg/dL	Avg mmol/L
5.0	97	5.4
5.7	117	6.5
6.0	126	7.0
6.5	140	7.8
7.0	154	8.6
7.5	169	9.4
8.0	183	10.2
9.0	212	11.8
10.0	240	13.3

Source: ADA Standards of Medical Care in Diabetes. A1C values are estimated averages — individual results vary.

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Summary

Instantly convert blood glucose between mg/dL (US) and mmol/L (international) and see where your reading falls in clinical reference ranges.

How it works

Enter your blood glucose value in either the mg/dL or mmol/L field.
The tool divides mg/dL by 18.0182 (or multiplies mmol/L by 18.0182) to convert.
Both converted values are displayed side by side.
A color-coded range indicator shows where the reading falls: normal, prediabetes, or diabetes territory.
Reference tables for fasting, post-meal, and estimated A1C values are shown below the result.

Use cases

Travelers switching between a US glucometer and an international one.
Healthcare providers interpreting foreign patient records.
Diabetics reading glucose values from apps or devices using different units.
Comparing fasting glucose results from different labs.
Understanding blood sugar context when reading clinical studies.
Patients reviewing international dietary or medication guidelines.

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu