function calculateFromA1C() {
var a1c = parseFloat(document.getElementById('a1c_input').value);
if (!isNaN(a1c) && a1c > 0) {
var mgdl = (28.7 * a1c) – 46.7;
var mmol = mgdl / 18.0182;
document.getElementById('mgdl_input').value = Math.round(mgdl);
document.getElementById('mmol_input').value = mmol.toFixed(1);
updateInterpretation(a1c);
} else {
clearDerivedFields();
}
}
function calculateFromMgdl() {
var mgdl = parseFloat(document.getElementById('mgdl_input').value);
if (!isNaN(mgdl) && mgdl > 0) {
var a1c = (mgdl + 46.7) / 28.7;
var mmol = mgdl / 18.0182;
document.getElementById('a1c_input').value = a1c.toFixed(1);
document.getElementById('mmol_input').value = mmol.toFixed(1);
updateInterpretation(a1c);
} else {
clearDerivedFields();
}
}
function calculateFromMmol() {
var mmol = parseFloat(document.getElementById('mmol_input').value);
if (!isNaN(mmol) && mmol > 0) {
var mgdl = mmol * 18.0182;
var a1c = (mgdl + 46.7) / 28.7;
document.getElementById('a1c_input').value = a1c.toFixed(1);
document.getElementById('mgdl_input').value = Math.round(mgdl);
updateInterpretation(a1c);
} else {
clearDerivedFields();
}
}
function updateInterpretation(a1c) {
var resultBox = document.getElementById('a1c_result_box');
var text = document.getElementById('interpretation_text');
resultBox.style.display = 'block';
if (a1c < 5.7) {
text.innerHTML = "Normal: Your A1C level is below 5.7%, which is within the normal range for a non-diabetic adult.";
resultBox.style.borderLeftColor = "#27ae60";
} else if (a1c >= 5.7 && a1c <= 6.4) {
text.innerHTML = "Prediabetes: An A1C between 5.7% and 6.4% indicates prediabetes. This means you are at higher risk for developing Type 2 diabetes.";
resultBox.style.borderLeftColor = "#f39c12";
} else if (a1c >= 6.5) {
text.innerHTML = "Diabetes: An A1C of 6.5% or higher on two separate tests indicates diabetes. Consult with your healthcare provider for management.";
resultBox.style.borderLeftColor = "#e74c3c";
}
}
function clearDerivedFields() {
document.getElementById('a1c_result_box').style.display = 'none';
}
function resetFields() {
document.getElementById('a1c_input').value = ";
document.getElementById('mgdl_input').value = ";
document.getElementById('mmol_input').value = ";
document.getElementById('a1c_result_box').style.display = 'none';
}
Understanding the A1C Calculator App
The Hemoglobin A1C test is a vital diagnostic tool for anyone managing diabetes or monitoring their metabolic health. Unlike daily finger-prick tests that measure your blood glucose at a single moment, the A1C provides a "big picture" view of your average blood sugar levels over the past two to three months.
How the A1C to eAG Conversion Works
The relationship between your A1C percentage and your Estimated Average Glucose (eAG) is linear. Our A1C calculator app uses the formula standardized by the ADAG (A1C-Derived Average Glucose) study:
eAG (mg/dL) = 28.7 × A1C – 46.7
eAG (mmol/L) = (28.7 × A1C – 46.7) / 18.0182
Interpreting Your A1C Results
According to the American Diabetes Association (ADA), the standard ranges for A1C results are:
A1C Level
Category
Below 5.7%
Normal
5.7% to 6.4%
Prediabetes
6.5% or Higher
Diabetes
Practical Examples
Using the A1C calculator app can help you visualize your progress. Here are three realistic scenarios:
A1C of 6.0%: This converts to an eAG of 126 mg/dL. This is in the prediabetes range.
A1C of 7.5%: This converts to an eAG of 169 mg/dL. For many adults with diabetes, the goal is to keep A1C below 7.0%.
A1C of 5.4%: This converts to an eAG of 108 mg/dL, which is considered a healthy average for a non-diabetic individual.
Why Use This Calculator?
Many patients are confused when they see their laboratory results. They might understand that their fasting glucose was 110 mg/dL this morning, but they don't know how that relates to an A1C of 8.2%. This tool bridges that gap by allowing you to switch between the two metrics instantly. By inputting your average daily glucose readings from your CGM (Continuous Glucose Monitor) or glucose meter, you can estimate what your next lab-drawn A1C might be.
Disclaimer: This A1C calculator app is for educational purposes only. It should not replace professional medical advice. Always consult with your endocrinologist or primary care physician regarding your diabetes management plan.