Why do some rounding conventions differ?

This calculator always applies the precise 18.016 factor rather than the common shorthand of 18. The difference is small (under 1% at typical glucose values) but can shift the last displayed digit compared to sources that round the factor first.

Glucose Unit Converter — mmol/L ↔ mg/dL

Q: Which unit is used where?

mg/dL is the standard unit in the United States. mmol/L is the SI unit used as the international standard in most other countries, including Canada, the UK, and Australia.

Test	Normal	Prediabetes	Diabetes range
Fasting	70–99 mg/dL (3.9–5.5 mmol/L)	100–125 mg/dL (5.6–6.9 mmol/L)	≥126 mg/dL (≥7.0 mmol/L)
2-hr OGTT (postprandial)	<140 mg/dL (<7.8 mmol/L)	140–199 mg/dL (7.8–11.0 mmol/L)	≥200 mg/dL (≥11.1 mmol/L)
Random (with symptoms)	—	—	≥200 mg/dL (≥11.1 mmol/L)

A1C (%)	eAG (mg/dL)	eAG (mmol/L)
5.0	97	5.4
6.0	126	7.0
7.0	154	8.6
8.0	183	10.2
9.0	212	11.7
10.0	240	13.3
11.0	269	14.9
12.0	298	16.5

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Walk-through

How to Use This Calculator

4 steps

1

Enter your glucose value and its unit

Type the blood glucose number on the Convert tab and choose which unit it's currently in — mg/dL (the US standard) or mmol/L (the international SI standard). The result updates instantly as you type.

2

Read the converted value

The hero number shows the same glucose level in the opposite unit, and the line below spells out both values together (e.g. '100 mg/dL = 5.6 mmol/L'). A reference band based on the fasting ADA ranges appears alongside it.

3

Check the full reference ranges

Open the Reference Ranges tab to see the fasting, 2-hour postprandial (OGTT), and random-glucose diagnostic bands side by side in both units, sourced from the ADA Standards of Care.

4

Optionally cross-check with A1C

If you have an A1C percentage, enter it on the A1C-Linked eAG tab to see the estimated average glucose it corresponds to over roughly the prior three months, in both mg/dL and mmol/L.

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Reference

Formula & Methodology

3 formulas

mg/dL from mmol/L

mg/dL = mmol/L * 18.016

18.016 is glucose's molar mass (180.16 g/mol) divided by 10. Multiplying an mmol/L reading by this factor gives the equivalent value in mg/dL, the unit used on most US lab reports.

mmol/L from mg/dL

mmol/L = mg/dL / 18.016

The inverse of the mg/dL formula. Dividing an mg/dL reading by 18.016 gives the equivalent value in mmol/L, the SI unit used as the international standard in most countries outside the US.

A1C-linked estimated average glucose (eAG)

eAG (mg/dL) = 28.7 * A1C(%) - 46.7

The ADAG Study Group's regression (Nathan et al., Diabetes Care 2008) linking A1C to the average glucose measured by continuous monitoring and self-testing over the prior ~3 months. The mmol/L value shown is this same result converted with the 18.016 factor above.

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YMYL-adjacent

Trust, Methodology & Sources

Reviewed by Calculover Editorial Review · Updated 2026-07-23 · 3 sources

Editorial accountability

Author: Quinn Sumner - Editor

Owner: Quinn Sumner - Editorial owner

Reviewer: Calculover Editorial Review - Clinical-source review

Last reviewed: 2026-07-23

Last verified: 2026-07-23

Data effective: 2026-07-23

Methodology

The calculator converts blood glucose between mg/dL and mmol/L using mg/dL = mmol/L * 18.016 (glucose molar mass 180.16 g/mol / 10), applied identically in both directions. Reference ranges (fasting, 2-hour postprandial, random) follow the ADA Standards of Care diagnostic thresholds. The A1C-linked eAG tab applies the ADAG Study Group's regression, eAG (mg/dL) = 28.7 * A1C(%) - 46.7 (Nathan et al., Diabetes Care 2008), and derives the mmol/L equivalent using the same 18.016 factor used everywhere else in the tool.

Assumption: The reference-range classification on the Convert tab assumes the entered value is a fasting reading; the Reference Ranges tab shows postprandial and random bands separately for non-fasting values.

Assumption: The A1C-to-eAG formula was derived from a population of adults with and without diabetes and is a population-level estimate, not an individual guarantee.

Limitations & guidance

This tool performs unit conversion and shows published reference ranges — it does not diagnose diabetes, prediabetes, or any other condition.

A single glucose reading does not confirm a diagnosis; ADA criteria typically require repeat testing or corroboration with an A1C or oral glucose tolerance test.

eAG is a population-derived estimate and can differ from an individual's true average glucose, especially with atypical red blood cell turnover or hemoglobin variants that affect A1C independent of glucose.

Professional guidance: This calculator is for education and reference only and is not medical advice, diagnosis, or treatment. Consult a physician to interpret any individual glucose or A1C result.

Primary sources

American Diabetes Association. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1):S27.

Nathan DM, et al; A1c-Derived Average Glucose (ADAG) Study Group. Translating the A1C Assay Into Estimated Average Glucose Values. Diabetes Care. 2008;31(8):1473-1478.

American Diabetes Association — eAG/A1C Conversion Calculator (professional.diabetes.org).

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Glossary

Key Terms Explained

6 terms

mmol/L Millimoles per liter — the SI (metric) unit for blood glucose concentration, used as the standard in most countries outside the United States.

mg/dL Milligrams per deciliter — the conventional unit for blood glucose used on most laboratory reports and glucose meters in the United States.

Blood glucose The concentration of glucose (sugar) circulating in the blood at a given moment, measured either from a fasting draw, after a meal, or via a random sample.

Conversion factor The fixed number (18.016 for glucose) used to convert a measurement from one unit to another. It comes from the molar mass of the substance being measured.

Molar mass of glucose 180.16 grams per mole — the mass of one mole of glucose molecules. Dividing by 10 gives the 18.016 factor used to convert between mg/dL and mmol/L.

eAG (estimated average glucose) A glucose value, in mg/dL or mmol/L, derived from an A1C percentage using a population regression. It approximates the average blood glucose over roughly the prior three months and is reported alongside A1C by many labs.

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Scenarios

Real-World Examples

3 worked examples

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US lab report reader

180 mg/dL → mmol/L

Glucose value 180 Unit mg/dL

180 / 18.016 ≈ 9.99, so 180 mg/dL is about 10.0 mmol/L. This is a post-meal (postprandial) level, which the Reference Ranges tab classifies as diabetes range (≥200 mg/dL / ≥11.1 mmol/L is diabetes; 180 mg/dL falls in the prediabetes 140–199 mg/dL band).

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International reading, US context

6.5 mmol/L → mg/dL

Glucose value 6.5 Unit mmol/L

6.5 × 18.016 ≈ 117.1, so 6.5 mmol/L is about 117 mg/dL. As a fasting reading, that falls in the ADA prediabetes range (100–125 mg/dL / 5.6–6.9 mmol/L).

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Fasting reading near a threshold

105 mg/dL fasting → reference band

Glucose value 105 Unit mg/dL (fasting)

105 / 18.016 ≈ 5.83, so 105 mg/dL is about 5.8 mmol/L. Both values fall in the ADA prediabetes fasting range (100–125 mg/dL / 5.6–6.9 mmol/L) — just above the 99 mg/dL / 5.5 mmol/L normal cutoff.

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Deep Dive

Understanding the Glucose Unit Converter

3 chapters · 3 min read

Blood glucose is reported in two different units depending on where you are: mg/dL in the United States, and mmol/L almost everywhere else. This calculator converts between them precisely and shows how a given reading compares to the standard ADA reference ranges, plus an optional A1C-linked estimate of average glucose.

Why two units exist

The United States reports blood glucose in milligrams per deciliter (mg/dL) — a mass-per-volume unit. Most of the rest of the world uses millimoles per liter (mmol/L), the SI unit that describes the actual molar concentration of glucose in the blood. Neither unit is more 'correct' than the other; they're just different conventions that became standard in different health systems, and travelers, researchers, and anyone reading international literature regularly need to convert between them.

How the conversion works

Glucose has a molar mass of 180.16 grams per mole. Dividing that by 10 (to reconcile deciliters with liters and milligrams with millimoles) gives the conversion factor used throughout this calculator: 18.016. Multiply an mmol/L value by 18.016 to get mg/dL, or divide an mg/dL value by 18.016 to get mmol/L. You'll sometimes see the shorthand '×18' used for quick mental math — it's accurate to within about half a percent, but this tool always applies the precise 18.016 factor so the last digit is never rounded twice.

Using reference ranges and eAG appropriately

The Reference Ranges tab lists the American Diabetes Association's fasting, 2-hour postprandial, and random-glucose diagnostic bands in both units. The A1C-Linked eAG tab translates an A1C percentage into the average glucose it implies over roughly the prior three months, using the ADAG Study Group's published regression. Both are reference tools, not diagnoses — a single glucose reading, or an eAG estimate, does not replace a physician's interpretation of the full clinical picture, repeat testing, or ongoing glucose monitoring.

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Questions

Frequently Asked Questions

6 questions

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

18.016 — glucose's molar mass (180.16 g/mol) divided by 10. Multiply mmol/L by 18.016 to get mg/dL, or divide mg/dL by 18.016 to get mmol/L. Some sources round this to 18 for quick mental math; this calculator always uses the precise 18.016 factor.

Which unit is used where?+

mg/dL is the standard unit on US lab reports and glucose meters. mmol/L is the SI unit and the international standard used in most other countries, including Canada, the UK, and Australia.

What is a normal fasting blood glucose?+

70–99 mg/dL (3.9–5.5 mmol/L) is considered normal fasting plasma glucose per the American Diabetes Association. 100–125 mg/dL (5.6–6.9 mmol/L) is classified as prediabetes, and 126 mg/dL (7.0 mmol/L) or higher is in the diabetes range.

What glucose level is used to diagnose diabetes?+

A fasting plasma glucose of 126 mg/dL (7.0 mmol/L) or higher is one ADA diagnostic reference threshold. This is a reference value only, not a diagnosis — clinical diagnosis typically requires repeat testing or confirmation with an A1C or oral glucose tolerance test, interpreted by a physician.

What is A1C-linked eAG?+

Estimated average glucose (eAG) translates an A1C percentage into the average blood glucose level it corresponds to over roughly the prior three months, using the ADAG Study Group's formula (Nathan et al., 2008). It's an optional cross-reference, not a substitute for direct glucose testing or continuous glucose monitoring.

Why might my numbers differ slightly from a rounded conversion?+

This calculator always applies the precise 18.016 factor rather than the common shorthand of 18. The difference is small — under half a percent at typical glucose values — but it can shift the last displayed digit compared to sources that round the factor first.

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Glucose Unit Converter

Glucose Value

Converted Value

Blood Glucose Reference Ranges

A1C

Estimated Average Glucose

Standard A1C-to-eAG Table

How to Use This Calculator

Enter your glucose value and its unit

Read the converted value

Check the full reference ranges

Optionally cross-check with A1C

Formula & Methodology

Trust, Methodology & Sources

Key Terms Explained

Real-World Examples

US lab report reader

International reading, US context

Fasting reading near a threshold

Understanding the Glucose Unit Converter

Why two units exist

How the conversion works

Using reference ranges and eAG appropriately

Frequently Asked Questions

Get a branded PDF of your results

Glucose Unit Converter

Glucose Value

Converted Value

Blood Glucose Reference Ranges

A1C

Estimated Average Glucose

Standard A1C-to-eAG Table

How to Use This Calculator

Enter your glucose value and its unit

Read the converted value

Check the full reference ranges

Optionally cross-check with A1C

Formula & Methodology

Trust, Methodology & Sources

Key Terms Explained

Real-World Examples

Understanding the Glucose Unit Converter

Why two units exist

How the conversion works

Using reference ranges and eAG appropriately

Frequently Asked Questions

Get a branded PDF of your results

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