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HbA1c ↔ Estimated Average Glucose (eAG) Converter

This tool applies the **ADAG 2008** regression *eAG (mg/dL) = 28.7 × A1C − 46.7* in both directions between HbA1c and estimated average glucose (eAG). Enter any of HbA1c (%), eAG (mg/dL) or eAG (mmol/L) to see all three values plus the ADA 2024 risk band (normal / prediabetes / diabetes) — built for matching lab reports against CGM or fingerstick averages.

HbA1c

6.5

%

eAG (mg/dL)

140

mg/dL

eAG (mmol/L)

7.8

mmol/L

Risk band (ADA 2024)

eAG (mg/dL) = 28.7 × A1C − 46.7 (ADAG 2008)

Notes

  • Linear fit from Nathan et al. (2008) ADAG study, n = 507, R² = 0.84 — adopted by the ADA and EASD as the standard A1C ↔ eAG conversion.
  • The ADA target for most adults with diabetes is HbA1c < 7 % (eAG ≈ 154 mg/dL ≈ 8.6 mmol/L); older or comorbid patients may use < 8 %.
  • Individual variation can reach ±0.5 %: red-cell lifespan (iron deficiency, haemolysis, CKD / dialysis), ethnicity and recent transfusion all skew A1C — pair with CGM / fingerstick where in doubt.

Formula

eAG (mg/dL) = 28.7 × HbA1c (%) − 46.7 HbA1c (%) = (eAG (mg/dL) + 46.7) ÷ 28.7 Glucose unit conversion: 1 mmol/L = 18.0182 mg/dL eAG (mmol/L) = eAG (mg/dL) ÷ 18.0182 ADA 2024 risk band: Normal : A1C < 5.7 % Prediabetes : 5.7 % ≤ A1C < 6.5 % Diabetes : A1C ≥ 6.5 % Treatment target: A1C < 7 % (eAG ≈ 154 mg/dL ≈ 8.6 mmol/L)

Frequently asked

My doctor says A1C 7 %, but my home meter averages 130 mg/dL — which is right?

**Both numbers can be correct — they measure different things**. **The ADAG formula says A1C 7 % ⇒ eAG ≈ 154 mg/dL**, so a meter average of 130 mg/dL is ≈ 24 mg/dL low. **Common causes**: (1) **fingerstick sampling bias** — most people test fasting / pre-meal and miss post-meal peaks, so **60–70 % of the day's hyperglycaemia is invisible** and the average looks low; (2) **no overnight testing** — the dawn phenomenon raises glucose 3–6 am and is invisible without CGM; (3) **physiology that raises A1C** — longer RBC lifespan (e.g. iron-deficient state) pushes A1C above the true mean. **The cleanest answer**: wear a CGM for 14 days and compute the GMI (glucose management indicator) against the lab A1C — the gap is usually < 0.3 %.

mg/dL vs mmol/L — I see "5.4" and "97" everywhere; how do they line up?

**Conversion factor 1 mmol/L = 18.0182 mg/dL** — derived from glucose's molar mass (180.156 g/mol) and rounded to 18.0 by ADA / IFCC. **Common benchmarks**: (a) **fasting upper-normal** — 100 mg/dL = 5.6 mmol/L; (b) **diabetes diagnosis (fasting)** — 126 mg/dL = 7.0 mmol/L; (c) **diabetes diagnosis (2-hr post-prandial)** — 200 mg/dL = 11.1 mmol/L; (d) **A1C 7 % (treatment target)** — eAG ≈ 154 mg/dL = 8.6 mmol/L; (e) **A1C 6.5 % (diagnostic cut-off)** — eAG ≈ 140 mg/dL = 7.8 mmol/L. **Regional usage**: USA, Germany, Japan, Brazil tend to use mg/dL; the UK, France, Spain, the Nordics, Canada, Australia, NZ, Hong Kong and Singapore use mmol/L.

Got A1C 5.9 % — that scared me. How fast does prediabetes turn into diabetes?

**Don't panic — but don't ignore it either**. **5.7–6.4 % is prediabetes** (ADA cut-off): insulin resistance is present but not yet diagnostic. **Progression rate**: the US *Diabetes Prevention Program* showed **untreated prediabetes progresses to T2DM at ≈ 5–10 % per year**, cumulative ≈ 30 % at 5 years and ≈ 50 % at 10 years. **Good news**: (1) **5–7 % weight loss + 150 min/week of moderate exercise cuts the risk by 58 %** (better than metformin's 31 %); (2) **Mediterranean / DASH diets** add independent risk reduction; (3) **better sleep + smoking cessation** improves insulin sensitivity. **Follow-up**: repeat A1C every 6 months; if it drops back to < 5.7 % the prediabetes is reversed — keep the habits going.

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Enter pre-pregnancy height and weight (for BMI), gestational week and current weight; the tool returns the recommended total weight-gain range and weekly rate for singleton or twins based on the Institute of Medicine (IOM/NAM 2009) guidelines, comparing to actual gain.

Life Expectancy by Current Age Calculator

Enter current age and sex; using the WHO Global Health Observatory period life table, the tool estimates remaining life expectancy and projected age at death assuming present-day mortality.

Sunscreen Amount & SPF Protection Time Calculator

Using the dermatology 2 mg/cm² standard, work out how many grams of sunscreen (≈ the "shot-glass rule") you need for full body or each zone, then estimate reapplication interval from the classic "SPF × natural burn time" formula.

Hike Difficulty (Petzoldt Energy Miles) Calculator

Enter trail distance, elevation gain and walking pace; using outdoor educator Paul Petzoldt's "energy miles" rule (+2 miles per 1,000 ft gain), the tool returns effective distance, estimated time and a difficulty rating.

Marathon Fueling Gels Calculator

Enter race distance, projected finish time and carb intake target (g/h); based on the 30–90 g/h sports nutrition range, returns how many gels and at what spacing.

Cooper 12-Minute Run VO₂max Calculator

Enter your 12-minute run distance (m or mi), age and sex; the tool estimates VO₂max via Cooper's 1968 JAMA formula and maps it to a six-band age/sex fitness classification.

Max Heart Rate (HRmax) Formula Comparison Calculator

Enter age (and optional resting HR); compare HRmax estimates from Fox (220−age), Tanaka, Gellish and the Nes / HUNT3 formula side-by-side, plus Karvonen training-zone bpm ranges.

Bone Density T-Score / Z-Score Interpretation Calculator

Enter DEXA-scan T-score (and optional Z-score); classifies as normal / osteopenia / osteoporosis per WHO 1994 + ISCD 2019 criteria and shows relative fracture-risk multiplier.

Cycling FTP (Functional Threshold Power) Estimator + Training Zones

Enter your best 20-minute average power (watts) to get your FTP (= 20-min × 0.95) and the seven Coggan training zones (Z1 Recovery through Z7 Neuromuscular).

WHO Oral Rehydration Solution (ORS) Recipe Calculator

Enter the total water volume (ml) — get the grams of salt, glucose (or substitute sucrose) and optional potassium chloride needed for a WHO/UNICEF low-osmolarity ORS, the standard rehydration recipe for diarrhoea worldwide.

Reading Glasses (Near-Add) Diopter by Age Calculator

Enter your age and habitual reading distance — get a quick estimate of the near-add power (+0.50 to +3.00 D) for off-the-shelf reading glasses, based on the Hofstetter 1944 accommodation formula and standard optometric guidance.