You can check your A1C at home using a fingerstick test kit available at most pharmacies, or estimate it from your average blood sugar readings using a simple formula. Home A1C kits work much like the rapid tests used in doctor’s offices, giving you a result in under 10 minutes. If you wear a continuous glucose monitor, you can also calculate an estimated A1C from your average glucose data without any additional testing.
Home A1C Test Kits
Several FDA-cleared home A1C test kits are sold over the counter. The A1C Now Self Check, the ReliOn Fast A1C Test, and the Walgreens At Home A1C Test Kit are all available without a prescription. Prices typically range from $30 to $50 for a single-use or two-test kit, and you can find them at major pharmacies and retailers like Walmart.
The process is straightforward and takes less than 10 minutes from start to finish. Each kit includes a lancet for pricking your finger, a blood collection device, and a small analyzer. After collecting a drop of blood, you place the sample into the analyzer within two minutes. The device processes the sample and displays your A1C percentage on screen. One important detail: most of these devices do not save your result after about 15 minutes, so write the number down as soon as it appears.
Estimating A1C From Average Blood Sugar
If you track your blood sugar with a standard glucose meter or a continuous glucose monitor (CGM), you can estimate your A1C using a conversion formula. This is the same calculation CGM systems use to generate what’s called a Glucose Management Indicator, or GMI.
The formula is:
Estimated A1C (%) = 3.31 + (0.02392 × your average glucose in mg/dL)
So if your average blood sugar over the past two to three months is 154 mg/dL, the math works out to 3.31 + (0.02392 × 154) = 6.98%, or roughly 7.0%. Here are a few common examples to give you a quick reference:
- Average glucose of 126 mg/dL: estimated A1C of about 6.3%
- Average glucose of 154 mg/dL: estimated A1C of about 7.0%
- Average glucose of 183 mg/dL: estimated A1C of about 7.7%
- Average glucose of 212 mg/dL: estimated A1C of about 8.4%
This calculation is most accurate when it’s based on a large number of readings spread across the full day, which is why CGMs tend to produce better estimates than occasional fingerstick checks. If you only test fasting glucose in the morning, your average will miss the spikes that happen after meals, and your estimated A1C will come out lower than reality.
What Your A1C Number Means
A1C reflects your average blood sugar over the past two to three months. It works by measuring how much sugar has attached to your red blood cells, which live for roughly 90 to 120 days. That long window is what makes it useful as a big-picture snapshot rather than a day-to-day reading.
The American Diabetes Association uses these thresholds:
- Below 5.7%: normal range
- 5.7% to 6.4%: prediabetes range
- 6.5% or higher: diabetes range
A home test result in the prediabetes or diabetes range is worth following up with a lab test. Home kits are useful for monitoring trends over time, but a formal diagnosis requires a lab-grade test ordered by a clinician.
When Home Results May Be Inaccurate
A1C measures sugar attached to hemoglobin in red blood cells, so anything that changes your red blood cells or hemoglobin can throw the number off. The CDC lists several conditions that can falsely raise or lower your result:
- Blood disorders like sickle cell anemia or thalassemia, which alter hemoglobin structure
- Severe anemia, which shortens red blood cell lifespan
- Kidney failure or liver disease
- Recent blood loss or blood transfusions
- Certain medications, including opioids and some HIV drugs
- Pregnancy, particularly early or late stages
If any of these apply to you, a home A1C test (or even a standard lab A1C) may not reflect your true blood sugar control. In those cases, your doctor will likely rely on other measures, such as fructosamine testing or direct glucose monitoring, to assess your levels.
How Often to Test at Home
Because A1C reflects a two-to-three-month average, testing more often than every three months won’t give you meaningfully different information. Most people who use home kits test quarterly, which lines up with the schedule most clinicians recommend for people managing diabetes. If your levels are stable and well-controlled, twice a year is often enough.
Keep in mind that home A1C results can vary slightly from lab results. Testing at the same time of day, following the kit instructions precisely, and using a kit that hasn’t expired all help improve consistency. If your home result and lab result differ by more than half a percentage point, consider switching brands or relying on lab testing for your baseline number while using home kits to spot trends between visits.