Glucose Calculator — Unit Conversion

Use the Glucose Calculator

Convert mg/dL ↔ mmol/L instantly with this glucose calculator—ideal for logs, reports, and quick comparisons.

Convert your reading

How to Use Glucose Calculator — Unit Conversion

1. Step 1: Enter a value

   Type your blood glucose reading into the input field.

2. Step 2: Pick input unit

   Choose whether your reading is in mg/dL or mmol/L.

3. Step 3: Select context

   Optionally select fasting, random, after meal, or 2‑hour test to see interpretation.

4. Step 4: View conversion

   The calculator instantly shows the equivalent value in the other unit.

5. Step 5: Copy and save

   Use the Copy button to paste the result into your notes or message.

Key Features

• Accurate mg/dL ↔ mmol/L conversion
• Instant mobile-friendly results
• Context-based interpretation
• Adjustable decimal precision
• Copy results to clipboard

Understanding Results

Formula

Glucose conversions use the glucose molecular weight (≈180.16 g/mol). One mmol/L of glucose equals about 18.0182 mg/dL. To convert mg/dL to mmol/L, divide by 18.0182 (≈18). To convert mmol/L to mg/dL, multiply by 18.0182.

• mg/dL → mmol/L: value ÷ 18.0182
• mmol/L → mg/dL: value × 18.0182

Reference Ranges & Interpretation

Interpretation depends on timing. Common fasting references: 70–99 mg/dL (3.9–5.5 mmol/L) typical; 100–125 mg/dL (5.6–6.9 mmol/L) suggests prediabetes risk; ≥126 mg/dL (≥7.0 mmol/L) on two mornings is diabetes‑level and should be confirmed clinically. Two‑hour oral glucose tolerance testing: <140 mg/dL (7.8 mmol/L) normal; 140–199 mg/dL (7.8–11.0 mmol/L) impaired; ≥200 mg/dL (≥11.1 mmol/L) diabetes‑level. After meals, many adults use <180 mg/dL (10.0 mmol/L) at 1–2 hours as a common target, adjusted to individual plans.

Consistent logs matter more than a single number. If results fall outside targets, consider meal composition, timing, stress, sleep, and activity before drawing conclusions.

Assumptions & Limitations

This tool converts units and summarizes widely used thresholds for education only. It does not diagnose, treat, or replace medical care. Meter technique, test timing, illness, medications, and individual plans affect interpretation. Seek medical advice for symptoms of severe low or high glucose.

Complete Guide: Glucose Calculator — Unit Conversion

Convert blood glucose values between mg/dL and mmol/L using our glucose calculator. Get quick, accurate conversions ideal for logs, reports, or comparisons.

The goal of this glucose calculator is simple: take a reading in one unit and instantly convert it to the other, while offering context for common situations like fasting, a random check, two‑hour oral glucose tolerance testing, or a post‑meal measurement. Clear numbers make it easier to track patterns, share results with your care team, and make day‑to‑day decisions about food, activity, and timing.

What is blood glucose?

Blood glucose is the amount of sugar circulating in your blood at a given moment. Glucose comes from the carbohydrates you eat and from your liver, which releases stored glucose between meals. Your body uses insulin to move glucose into cells for energy. When this system works well, glucose stays within a healthy range. When it does not, values can run low (hypoglycemia) or high (hyperglycemia), and over time, elevated glucose can damage blood vessels, nerves, kidneys, and eyes.

Two units are common worldwide: milligrams per deciliter (mg/dL), often used in the United States, and millimoles per liter (mmol/L), widely used internationally. You may see both in articles, lab reports, and device manuals. That is why a reliable glucose calculator is helpful — it eliminates guesswork and ensures your notes, logs, and communications show the unit that is most familiar to you or your clinician.

How to use the glucose calculator

Using the tool is designed to be quick on any phone. Choose whether you are entering mg/dL or mmol/L, type your value, and the conversion appears instantly. You can select a reading context — fasting, after a meal, two‑hour OGTT, or random — to see a short interpretation that maps to widely cited thresholds. Tap Copy to place the result string (both units) on your clipboard for pasting into a note or message.

For example, if your meter shows 95 mg/dL in the morning before breakfast, the calculator converts this to approximately 5.27 mmol/L. If you switch the input unit to mmol/L, the tool preserves your displayed number and converts in the other direction, so you never lose the value you just typed.

Conversion formula explained

Glucose conversions rest on the molecular weight of glucose, approximately 180.16 g/mol. One mmol/L of glucose corresponds to 18.0182 mg/dL. In practice, many references round this factor to 18 for convenience. Our calculator uses the precise factor internally and lets you control decimal places for more readable results.

• mg/dL → mmol/L: divide by 18.0182 (≈18)
• mmol/L → mg/dL: multiply by 18.0182 (≈18)

Precision expectations differ by unit: mg/dL is often shown with 0 decimal places on meters and reports, while mmol/L is commonly shown to one or two decimals. Adjust the decimals to match your log or app. Consistent formatting reduces misreads when you look back over time.

Typical ranges & targets

Interpreting a single glucose value depends on timing and context. For fasting values (no calories for at least eight hours), many guidelines consider 70–99 mg/dL (3.9–5.5 mmol/L) as a typical reference range. Fasting values of 100–125 mg/dL (5.6–6.9 mmol/L) can indicate prediabetes risk, while 126 mg/dL (7.0 mmol/L) or higher on two separate mornings meets a diagnostic threshold for diabetes in many standards of care. For two‑hour oral glucose tolerance testing, fewer than 140 mg/dL (7.8 mmol/L) is considered normal, 140–199 mg/dL (7.8–11.0 mmol/L) suggests impaired glucose tolerance, and 200 mg/dL (11.1 mmol/L) or higher is a diabetes‑level result that warrants clinical confirmation.

After meals, personal targets may differ based on age, health status, and an individualized plan. A common goal used in practice is less than 180 mg/dL (10.0 mmol/L) one to two hours after starting a meal. Some people, under clinician direction, use lower targets. Trends across days matter more than any single reading.

For deeper context, many clinicians also review A1C, a lab value reflecting average glucose over roughly three months. If you are exploring averages and long‑term risk, our A1C Calculator can help you connect day‑to‑day readings with estimated averages.

Fasting vs. post‑meal readings

Fasting values tend to be more stable because they are measured after a period of not eating. Hormones that counterbalance insulin — such as glucagon — help maintain glucose overnight. Post‑meal values rise as carbohydrates are digested and absorbed. The shape and height of that rise depend on the meal composition (carbs, fiber, fat, protein), insulin response, stress, sleep, and activity.

If you are seeing higher spikes after specific meals, try simple experiments: choose smaller portions of quickly absorbed carbohydrates, add fiber or protein, or take a short walk after eating if your clinician agrees it is safe. Our Carb Calculator can help estimate carbohydrate load and prepare you for the likely size of a post‑meal rise.

Warning signs: low, high, and when to seek help

Low blood glucose can cause shakiness, sweating, hunger, irritability, rapid heartbeat, and in severe cases confusion or loss of consciousness. High blood glucose can cause thirst, frequent urination, fatigue, and blurry vision. For people with diabetes, consistently high readings raise the risk of diabetic ketoacidosis (DKA) or hyperosmolar crises in specific contexts. If you experience symptoms of severe low or high glucose, follow your emergency plan and seek medical care.

For general education on targets and diagnostic criteria, see the American Diabetes Association overview and the CDC Diabetes hub. These sites provide non‑commercial guidance and background.

Glucose units around the world

The mg/dL unit dominates in the United States and some parts of Asia. Most of Europe, Canada, Australia, New Zealand, and others use mmol/L. If you are reading an article, research paper, or device thread from another country, unit differences can cause confusion. Our glucose calculator bridges this gap so you can compare readings and recommendations across sources without mental math.

If you keep a shared log with family members or a clinician, pick one unit and stick with it in your notes. You can always convert incoming values and store the converted number next to the original. Consistency prevents transcription errors and makes patterns easier to spot.

Unit conversion quick check

To convert between units, 1 mmol/L is approximately 18 mg/dL. Multiplying mmol/L by 18 (or dividing mg/dL by 18) will get you very close to the calculator’s exact value. Rounding practices differ by device and lab; some show whole numbers, others one decimal. The glucose calculator standardizes the math so your notes and charts are comparable over time even if your meter’s display format changes.

Logging & tracking tips

Good logs are short and useful. Include date and time, the reading with both units if you need to share internationally, and a short label for the context (e.g., "fasting" or "2‑hour after lunch"). Mark unusual events like illness or poor sleep. When possible, pair readings with activity — even a 10–15 minute walk may visibly change a post‑meal curve.

If a clinician has asked you to track related measures, our tools can help: estimate daily energy needs with the TDEE Calculator, monitor weight trends with the Weight Loss Percentage Calculator, and review cardiovascular risk factors with the Cholesterol Calculator.

Common mistakes to avoid

• Mixing units: Logging a mmol/L reading as mg/dL (or vice versa) changes the number by a factor of ~18. Always label units clearly.
• Over‑interpreting one reading: A single number rarely changes the story. Look for patterns across days.
• Ignoring context: Eating, activity, stress, and illness strongly affect glucose. Note these in your log.
• Skipping meter hygiene: Wash and dry hands before testing; follow strip/storage instructions to avoid false results.
• Rounding too early: If you convert mmol/L to mg/dL, keep decimals until final logging, then format consistently.

If you are exploring insulin adjustments or carbohydrate dosing, use this calculator alongside guidance from your care team. For structured estimates, try our Insulin Calculator and pair it with carbohydrate estimates from the Food Nutrition Calculator when planning meals.

Next steps & related tools

Numbers are most helpful when they answer a question you care about. If you want to know whether your typical mornings are trending up or down, check fasting values a few times per week and scan for patterns. If you are curious about how a favorite lunch affects you, take a reading at about one hour and again at two hours. Convert units as needed with this glucose calculator and keep your notes consistent.

• Blood Sugar Calculator — additional formats and context options.
• A1C Calculator — connect daily readings with long‑term averages.
• Diabetes Risk Calculator — explore risk factors beyond glucose alone.
• Adult BMI Calculator — track a common cardiometabolic measure.
• Blood Pressure Calculator — review another vital cardiovascular metric.

Health decisions should be made with a clinician who knows your history. Use these tools to organize information and make your appointments more productive. Bring your questions and your log — and remember that small, consistent changes in meals, movement, and sleep can steadily improve glucose patterns.

When you review your log, look for patterns more than perfection. A gentle downward drift in fasting numbers or smaller post‑meal spikes across several weeks signals progress—even if individual readings vary. Keep the unit label consistent, and let the glucose calculator do the conversions so you can focus on the trend.

Frequently Asked Questions