A small set of calculators built on published formulas, with the limits of each stated plainly. All free, no sign-up, and nothing you enter leaves your browser.
The calculators
- A1C Calculator: Convert A1C to Average Blood Sugar
Enter an A1C result to see the estimated average glucose it corresponds to — or work backwards from a glucose value to the A1C it implies. - Calorie Calculator: How Many Calories to Lose Weight
Estimates a daily calorie target for weight loss — and, unlike most calculators, shows you how wide the real margin of error is. - Blood Pressure Checker: What Your Reading Means
Enter a reading to see where it sits in the standard categories. Ideally use your seven-day average rather than a single measurement. - Waist-to-Height Ratio Calculator
Divide your waist by your height and you get a risk marker that outperforms BMI — using nothing but a tape measure. - Bedtime Calculator: When Should You Go to Sleep?
Set the time you have to wake up and this works backwards to a bedtime, allowing for how long you take to fall asleep.
Why these show their limits
Most health calculators hand you a confident number and stop there. A calorie estimate carries a margin of error of roughly 20% in either direction; an A1C can be distorted by anemia; a bedtime built on tidy 90-minute sleep cycles rests on an oversimplification. Each tool here says so, because a number without its uncertainty is worse than no number at all.
These calculators are for general education and are not medical advice or a diagnosis. Always discuss your own numbers with your doctor.