Blood Sugar Log
Log a reading in seconds and see your average, estimated A1C and time in range, with patterns by meal. Saved only in this browser, with a printable report for your doctor.
ExampleExample log · average over 14 days
137mg/dL
Estimated A1C about 6.4%, from 41 readings on 14 days.
- In range (70–180)
- 93%
- Lows (under 70)
- 1
- Highs (over 180)
- 2
Your readings
Your readings will appear here, newest first. They’re saved only in this browser: nothing is sent anywhere. Already keeping a log in a spreadsheet? Use Import CSV in the ⋯ menu.
Your targetsRange 70–180 mg/dL
Defaults are the ADA and time-in-range consensus targets. Your care team may set different ones (for example in pregnancy, or for older adults); change them here and every number on the page follows.
How the numbers are worked outADAG, time-in-range consensus and ADA targets
Average is the mean of your readings in the period. Estimated A1C uses the ADAG formula, A1C (%) = (average mg/dL + 46.7) / 28.7 (Nathan et al., Diabetes Care 2008), and is shown once there are at least 14 readings on 7 days. Readings taken at set times can miss highs and lows in between, so compare it with a lab A1C.
In range is the share of readings between your low and high targets (70–180 mg/dL by default, from the international time-in-range consensus, Battelino et al., Diabetes Care 2019). With finger-stick readings this is a share of readings, not of the day as a CGM measures it.
Targets by meal: before meals 80–130 mg/dL and under 180 mg/dL 1–2 hours after starting a meal (ADA Standards of Care in Diabetes 2025, section 6). Lows: under 70 mg/dL (level 1) and under 54 mg/dL (level 2).
mmol/L = mg/dL ÷ 18.0182. This log is for keeping track, not for diagnosis or treatment decisions.
Frequently Asked Questions
Where are my readings saved?
Only in this browser, on this device. Nothing is sent to Binary Decimal and readings never go into the page address. To keep a copy or move to another phone or computer, use Backup & sync (linked in the footer), or download a CSV from the ⋯ menu.
What is a normal blood sugar?
Without diabetes, fasting glucose is usually 70–99 mg/dL (3.9–5.5 mmol/L). For most adults with diabetes, the American Diabetes Association suggests 80–130 mg/dL (4.4–7.2 mmol/L) before meals and under 180 mg/dL (10.0 mmol/L) 1–2 hours after starting a meal. Your care team may set different targets, for example in pregnancy or for older adults; you can change them under “Your targets”.
How is the estimated A1C worked out, and how accurate is it?
It uses the ADAG study formula: A1C (%) = (average glucose in mg/dL + 46.7) / 28.7. It needs about two weeks of readings (at least 14 on 7 different days) before it is shown. Finger-stick readings taken at set times don’t capture the whole day, and a lab A1C reflects roughly three months, so treat it as a guide and compare it with your lab result.
What counts as low or high?
Below 70 mg/dL (3.9 mmol/L) is low and below 54 mg/dL (3.0 mmol/L) is very low (ADA level 1 and level 2 hypoglycaemia). Time-in-range guidelines treat 70–180 mg/dL (3.9–10.0 mmol/L) as the target range and above 250 mg/dL (13.9 mmol/L) as very high. If you have symptoms or readings outside your range, follow the plan from your care team.
How often should I check my blood sugar?
It depends on your treatment, so follow your care team’s advice. People using insulin often check several times a day; others may check less often, for example a fasting reading plus a reading after different meals to learn how food affects them.
Can I print a log for my doctor?
Yes. “Print report for my doctor” in the ⋯ menu prints the period you’re viewing as a table by day and meal, with your average, estimated A1C and time in range. “Print a blank log sheet” prints a weekly paper sheet to fill in by hand.
Can I import readings from my meter or CGM?
You can import a CSV file with a date column (YYYY-MM-DD), a time column (HH:MM) and a glucose column in mg/dL or mmol/L; context and note columns are optional. Direct import of Dexcom and Libre exports is planned.