estimatea1c.com › Guides › Time in range
A1C gives you one number for three months. Time in range shows how much of each day you actually spent in a healthy glucose band — and for a lot of people, that's the more useful target to chase. Here's what "good" looks like, and how it lines up with A1C.
Time in range (TIR) is the percentage of your readings that fall inside the standard target band: 70–180 mg/dL (3.9–10.0 mmol/L). The flip side splits into time below range (TBR, <70) and time above range (TAR, >180). It's most precise from a CGM, but you can approximate it from frequent fingersticks too.
A day split into below / in / above range. The goal is to grow the green.
The international consensus targets (Battelino et al., 2019, adopted by the ADA) for most non-pregnant adults with type 1 or type 2 diabetes:
| Metric | Band | Goal |
|---|---|---|
| Time in range | 70–180 mg/dL | > 70% of the day |
| Time below range | < 70 mg/dL | < 4% |
| Time very low | < 54 mg/dL | < 1% |
| Time above range | > 180 mg/dL | < 25% |
| Time very high | > 250 mg/dL | < 5% |
Two important adjustments: older or higher-risk adults aim for >50% TIR with <1% below range (avoiding lows matters more than chasing perfection), and pregnancy with type 1 uses a tighter 63–140 mg/dL band, >70%. And you don't need perfection to benefit — every 5% increase in time in range is clinically meaningful.
They track closely. A widely used rule of thumb: roughly every 10% of time in range ≈ 0.5% of A1C, with 70% TIR landing near a 7% A1C.
| Time in range | Approx. A1C |
|---|---|
| 90% | ~6.0% |
| 70% | ~7.0% |
| 50% | ~8.0% |
| 40% | ~8.5% |
A rough approximation — your real A1C depends on more than TIR.
Two people can share an identical 7% A1C and live completely different days. One holds steady around 150 mg/dL; the other swings between dangerous lows and 300s that happen to average to the same place. A1C can't tell them apart — time in range can, because it also exposes how often you dip too low, which a three-month average quietly hides. That's why TIR is increasingly used alongside A1C, not instead of it.
The levers are the same ones that lower average glucose: meal sequencing, a short walk after eating, better sleep, and modest weight loss. We break them down in how to lower your A1C without medication. The fastest gains usually come from flattening post-meal spikes and trimming overnight highs.
SteadyRange logs your glucose and weight, shows your time in range and estimated A1C as they trend, and exports a clean PDF for your next appointment. Private by default.
Try SteadyRange →For most adults with diabetes, more than 70% of the day between 70–180 mg/dL, with less than 4% below 70. Older or higher-risk people aim for >50% with minimal lows.
About 70% time in range corresponds to roughly a 7% A1C. As a rule of thumb, each 10% change in TIR shifts A1C by about 0.5%.
Yes — that's excellent, in the neighborhood of a 6.5% A1C. Above 70% already exceeds the standard goal; keep an eye on lows as you tighten.
A CGM gives the most accurate TIR because it samples continuously. You can estimate it from frequent fingersticks, but with less precision.
Medical disclaimer. General education, not medical advice. Targets are population guidelines; your personal goals may differ — set them with your care team. The TIR→A1C figures are approximations. Do not change treatment based on this page.