Blood Sugar to A1C Converter
Convert your average blood sugar level to an estimated A1C percentage. Enter your value in mg/dL or mmol/L.
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Blood Sugar to A1C Formula
The reverse ADAG formula converts estimated average glucose back to A1C percentage:
Example 1: Average glucose of 126 mg/dL
A1C = (126 + 46.7) / 28.7 = 172.7 / 28.7 = 6.0%
Category: Prediabetes
Example 2: Average glucose of 183 mg/dL
A1C = (183 + 46.7) / 28.7 = 229.7 / 28.7 = 8.0%
Category: Diabetes
Blood Sugar to A1C Conversion Table
Use this reference table to quickly convert blood sugar to A1C. Values shown for average glucose from 70 to 300 mg/dL.
| Avg Glucose (mg/dL) | Avg Glucose (mmol/L) | A1C (%) | Category |
|---|---|---|---|
| 70 | 3.9 | 4.1% | Normal |
| 80 | 4.4 | 4.4% | Normal |
| 90 | 5.0 | 4.8% | Normal |
| 100 | 5.5 | 5.1% | Normal |
| 110 | 6.1 | 5.5% | Normal |
| 120 | 6.7 | 5.8% | Prediabetes |
| 130 | 7.2 | 6.2% | Prediabetes |
| 140 | 7.8 | 6.5% | Diabetes |
| 150 | 8.3 | 6.9% | Diabetes |
| 160 | 8.9 | 7.2% | Diabetes |
| 170 | 9.4 | 7.6% | Diabetes |
| 180 | 10.0 | 7.9% | Diabetes |
| 190 | 10.5 | 8.2% | Diabetes |
| 200 | 11.1 | 8.6% | Diabetes |
| 210 | 11.7 | 8.9% | Diabetes |
| 220 | 12.2 | 9.3% | Diabetes |
| 230 | 12.8 | 9.6% | Diabetes |
| 240 | 13.3 | 10.0% | Diabetes |
| 250 | 13.9 | 10.3% | Diabetes |
| 260 | 14.4 | 10.7% | Diabetes |
| 270 | 15.0 | 11.0% | Diabetes |
| 280 | 15.5 | 11.4% | Diabetes |
| 290 | 16.1 | 11.7% | Diabetes |
| 300 | 16.6 | 12.1% | Diabetes |
Understanding Blood Sugar to A1C Conversion
Converting your average blood sugar to A1C helps you estimate what your next lab test might show. This is especially useful if you use a continuous glucose monitor (CGM) or test frequently with a finger-prick meter, as these devices report glucose in mg/dL or mmol/L rather than as an A1C percentage.
Keep in mind that the reverse ADAG formula provides an estimate. Your actual lab A1C may differ slightly because the A1C test measures glycated hemoglobin directly, while this calculator works backward from glucose values. Factors like red blood cell lifespan, hemoglobin variants, and recent blood loss can cause discrepancies between estimated and lab-measured A1C.
For the most accurate results, use glucose readings taken consistently over 2-3 months — not just a few days of data. The more readings you average, the closer your estimated A1C will be to the lab value.
Tips for Accurate Blood Sugar Averaging
The accuracy of your blood sugar to A1C conversion depends heavily on the quality of the glucose data you input. To get the most reliable estimate, test your blood sugar at different times throughout the day, including fasting readings (before breakfast), pre-meal levels, post-meal readings (1-2 hours after eating), and bedtime checks. This variety captures the full range of your daily glucose fluctuations.
For best accuracy, include at least 2 to 3 months of readings in your average. Short-term data from just a few days or weeks may not reflect your true long-term blood sugar patterns, leading to inaccurate A1C estimates.
If you use a continuous glucose monitor (CGM), your data will provide the most complete and accurate picture of your glucose levels, as CGMs capture readings every few minutes around the clock, including overnight values that finger-prick testing often misses.
Avoid averaging only fasting blood sugar readings, as this common mistake tends to underestimate your actual A1C. Fasting values are typically the lowest readings of the day and do not account for post-meal spikes that significantly influence your A1C level.
Blood Sugar Targets for Diabetes Management
The American Diabetes Association (ADA) provides specific blood sugar targets for adults with diabetes to help guide daily management. For fasting blood sugar and pre-meal glucose, the recommended target is 80 to 130 mg/dL (4.4 to 7.2 mmol/L). Keeping your fasting levels within this range is an important step toward achieving a healthy A1C.
For post-meal blood sugar, measured 1 to 2 hours after the start of a meal, the ADA recommends a target of below 180 mg/dL (10.0 mmol/L). Post-meal spikes are a major contributor to elevated A1C levels, so managing these peaks through diet, exercise timing, and medication is essential.
Together, these blood sugar targets correspond to an A1C below 7%, which is the general goal recommended by the ADA for most adults with diabetes. Achieving this target has been shown to reduce the risk of diabetes complications, including nerve damage, kidney disease, and vision problems.
It is important to note that blood sugar targets may be individualized by your doctor based on your age, overall health, duration of diabetes, and risk of hypoglycemia. Some patients may be given a more relaxed target of A1C below 8%, while others may aim for tighter control below 6.5%.
Frequently Asked Questions
How do I convert blood sugar to A1C?
Use the reverse ADAG formula: A1C (%) = (eAG in mg/dL + 46.7) / 28.7. For mmol/L: A1C (%) = (eAG in mmol/L + 2.5944) / 1.5944. For example, an average glucose of 154 mg/dL converts to an A1C of about 7.0%.
What average blood sugar equals an A1C of 6.5%?
An A1C of 6.5% corresponds to an estimated average glucose of approximately 140 mg/dL (7.8 mmol/L). This is the diagnostic threshold for diabetes according to the American Diabetes Association.
Can I use my home glucose readings to estimate A1C?
Yes, if you have a good average of your glucose readings over time, you can use this converter to estimate your A1C. However, home readings may not capture overnight levels or post-meal spikes as comprehensively as a lab A1C test.