Enter the time in range percentage your CGM app reports (the share of the day between 70 and 180 mg/dL, or 3.9 to 10.0 mmol/L) and see what it means in hours, against the consensus targets, and as an approximate A1C.
In range per day:
Approximate A1C: (rough research-based estimate, see below)
How is time in range calculated?
Time in range is the share of your glucose readings that fall between 70 and 180 mg/dL (3.9 to 10.0 mmol/L). How to calculate time in range yourself: divide the readings in range by all readings and multiply by 100. To turn the percentage into hours, multiply it by 24 and divide by 100, which is what this time in range calculator does for you. Every 10% of time in range is about 2.4 hours of the day, and every 5% is about 72 minutes.
Your CGM app does this count for you over whatever period you pick. The international consensus (Battelino et al., Diabetes Care 2019) recommends judging time in range over at least 14 days of CGM data, with the sensor active for about 70 percent of that time, because a few days or a patchy record can swing the percentage a lot.
A blood glucose meter log can only approximate the same number. A handful of finger-stick readings a day misses the overnight and between-meal hours that a CGM records every few minutes, so treat a meter-based percentage as a rough estimate and read the consensus targets as CGM targets.
Worked example: 65% time in range is 15 hours 36 minutes a day in range. That is 5 points, or about 72 minutes a day, short of the 70% goal.
Where to find your time in range
- Dexcom: the G7 app shows time in range on the Clarity card under the trend graph, for the last 3, 7, 14, 30 or 90 days, next to your average glucose and GMI (Dexcom support). The Dexcom Clarity app and website show the same percentage with the time above and time below range split out.
- FreeStyle Libre: the Libre apps call the same metric Time in Target. Open the menu, then Reports, then Time in Target to see the share of readings within, above and below your target range. LibreView reports carry the same breakdown.
- Sugar Sense: the Statistics tab calculates time in range from your connected CGM for today and the last 7, 30 and 90 days, using the same thresholds that drive your alerts, and keeps a streak of the days that hit your goal. It is free on every plan.
- Nightscout and printed clinic reports: any report that lists in range, above range and below range percentages gives you the same number. Enter the in range figure above, and the below range figure in the optional field.
The consensus targets
The 2019 international consensus on CGM data (Battelino et al., Diabetes Care 2019) recommends these goals for most adults with type 1 or type 2 diabetes:
| Metric | Most adults | Older or higher-risk adults |
|---|---|---|
| Time in range (70-180 mg/dL) | more than 70% | more than 50% |
| Time below 70 mg/dL | less than 4% | less than 1% |
| Time below 54 mg/dL | less than 1% | not separately specified |
| Time above 180 mg/dL | less than 25% | less than 50% |
| Time above 250 mg/dL | less than 5% | less than 10% |
During pregnancy the consensus uses a tighter 63 to 140 mg/dL (3.5 to 7.8 mmol/L) range with a goal of more than 70% inside it. Targets are always individual: the right goal for you is the one agreed with your care team.
Time in range vs A1C: hours per day and the A1C it roughly maps to
Two published analyses anchor the estimate. Beck et al., J Diabetes Sci Technol 2019 compared CGM data with laboratory A1C and found that 70 percent time in range corresponded on average to an A1C of about 7 percent, and 50 percent to about 8 percent, with each 10-point rise in TIR matching a 0.6-point fall in A1C on average. A pooled analysis of 18 studies by Vigersky and McMahon, Diabetes Technol Ther 2019 put the slope at 0.8 points per 10 percent. The time in range chart below and the calculator above use the Beck anchors (70 percent is 7.0 percent, 50 percent is 8.0 percent) and extend that line in 0.5-point steps. Both papers found a wide spread of A1C values behind any single TIR figure, so treat the estimate as orientation, not as a lab result.
| Time in range | Hours per day | Approximate A1C |
|---|---|---|
| 40% | 9 h 36 min | 8.5% |
| 50% | 12 h 0 min | 8.0% |
| 60% | 14 h 24 min | 7.5% |
| 70% | 16 h 48 min | 7.0% |
| 80% | 19 h 12 min | 6.5% |
| 90% | 21 h 36 min | 6.0% |
Why the percentage matters: in the DCCT data, each 10 percentage points lower time in range went with a 64 percent higher rate of retinopathy progression and a 40 percent higher rate of microalbuminuria (Beck et al., Diabetes Care 2019). That is why time in range sits next to A1C on modern reports instead of replacing it.
Want the full story of what TIR is and why it became the headline CGM metric? Read Time in Range explained. To translate a lab A1C into average glucose (or the other way round), use the A1C calculator.
Frequently asked questions
What is a good time in range?
The international consensus recommends spending more than 70% of the day between 70 and 180 mg/dL (3.9 to 10.0 mmol/L) for most adults with type 1 or type 2 diabetes, with less than 4% of the day below 70 mg/dL. For older adults or people at higher risk of lows, more than 50% in range is the recommended, more conservative goal.
How is time in range calculated?
Readings between 70 and 180 mg/dL divided by all readings, times 100. Your CGM app does the count for you over the period you choose, and the consensus recommends at least 14 days of data with the sensor worn about 70% of the time. To convert the percentage into hours, multiply by 24 and divide by 100: 60% is 14 hours 24 minutes, 80% is 19 hours 12 minutes.
How many hours a day is 70% time in range?
70% of 24 hours is 16.8 hours, so about 16 hours 48 minutes in range. A useful rule of thumb: every 10% of time in range equals about 2.4 hours of the day, and every 5% about 72 minutes.
What glucose range does time in range use?
The standard range is 70 to 180 mg/dL (3.9 to 10.0 mmol/L). During pregnancy a tighter range of 63 to 140 mg/dL (3.5 to 7.8 mmol/L) is used. Some people also track a personal, tighter range with their care team, but published targets refer to the standard range. You can convert any threshold with our blood sugar unit converter.
Is time in range better than A1C?
Neither replaces the other. A1C compresses about three months into a single number, while time in range shows how much of the day you actually spend in range and reveals the swings an average can hide. Published analyses map each 10 percentage points of TIR to roughly 0.5 to 0.8 points of A1C, which is the relationship the estimate on this page is based on. Use A1C for the long view and time in range for the day-to-day picture, and turn a lab A1C into average glucose with our A1C calculator.
How does Sugar Sense track time in range?
Automatically. Sugar Sense calculates your time in range from your CGM readings for today and the last 7, 30 or 90 days, using the same thresholds that drive your alerts, and it is completely free. You can even build streaks for days that hit your TIR goal.
More free tools
This tool is for education only. It is not medical advice, it does not replace laboratory testing, and it must never be used for insulin dosing or other treatment decisions. Always work with your healthcare team. See our full medical disclaimer.
