MedCalcTools runs common clinical reference calculations from published medical equations. Every tool shows its formula, cites the original source, and carries a clear reminder that it is for education, not diagnosis or treatment.
MedCalcTools calculates BMI, A1C to eAG, GFR, creatinine clearance, corrected calcium, LDL cholesterol, body surface area, and sodium correction using eight named, published clinical equations, each cited on its own page, for educational use only.
Enter weight and height to see your CDC weight category.
Open full BMI calculatorEvery tool here runs a single named equation. No composite scores, no proprietary weighting. Pick the one you need and the source is right there on the page.
Body mass index from height and weight, with CDC weight categories.
Crunch it →Convert A1C percent to estimated average glucose (eAG) and back, using the ADA/NIDDK equation.
Crunch it →Estimate creatinine clearance with the Cockcroft-Gault equation from age, weight, sex, and serum creatinine.
Crunch it →Estimate glomerular filtration rate with the 2021 CKD-EPI creatinine equation.
Crunch it →Adjust total serum calcium for low albumin using the Payne formula.
Crunch it →Estimate body surface area for dosing references using the Mosteller formula.
Crunch it →Estimate LDL cholesterol from a lipid panel using the Friedewald equation.
Crunch it →Correct measured sodium for hyperglycemia using the Katz and Hillier factors.
Crunch it →Every named equation this site uses, in one dated, sourced, downloadable table.
View the dataset →Each calculator names the equation it uses and links to the publishing body, such as the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the American Diabetes Association (ADA), and the National Kidney Foundation. You can read the source and decide for yourself whether the math fits your situation.
Most visitors already know why they are here. Someone tracking a fasting glucose result wants A1C to eAG, not BMI. A caregiver adjusting a prescription for an older relative with reduced kidney function wants creatinine clearance or eGFR, and those two are not interchangeable: Cockcroft-Gault reports clearance in mL/min and is the equation most drug-dosing tables were built around, while the 2021 CKD-EPI formula reports eGFR normalized to body surface area and is the one used for staging chronic kidney disease. Picking the wrong one does not just give a slightly different number, it answers a different question.
The same split shows up elsewhere on the site. Corrected calcium and sodium correction both exist because a single lab value can mislead when something else in the blood is off, low albumin in the calcium case, high glucose in the sodium case. LDL cholesterol here is calculated with the Friedewald equation from a standard lipid panel, which is why the tool asks for total cholesterol, HDL, and triglycerides rather than LDL directly. Body surface area matters mostly for dosing certain medications and is rarely something a patient looks up out of curiosity.
Take the BMI calculator, since it is the simplest to check by hand. Enter 70 kg and 170 cm and the page runs BMI = weight in kilograms divided by height in meters squared. Height in meters is 1.70, squared that is 2.89, and 70 divided by 2.89 works out to 24.2. The same JavaScript that runs the live tile on this page classifies that result using the CDC's four adult ranges: under 18.5 is underweight, 18.5 to 24.9 is healthy weight, 25.0 to 29.9 is overweight, and 30.0 or above is obesity. A BMI of 24.2 lands just inside the healthy weight band, less than a full point below the overweight cutoff.
That last detail is the point of showing the math instead of just the answer. A result that sits close to a category boundary is more sensitive to small measurement errors, a stale weight, or height that was estimated rather than measured, than one sitting in the middle of a range. Knowing where your number falls relative to the cutoff tells you how much to trust the category label, not just the label itself.
Every equation on this site answers a narrow question well and a broader one not at all. BMI does not know whether the weight it was given is mostly muscle or mostly fat. Cockcroft-Gault was derived and validated using actual body weight, and results can shift depending on whether a clinician instead uses ideal or adjusted weight for someone at the extremes of size. The sodium correction tools show two published coefficients, 0.016 from Katz and 0.024 from Hillier, precisely because there is no single right answer at very high glucose levels, only competing estimates with different error patterns.
None of that is a flaw in the formulas. It is why they are reference tools and not diagnoses. If a result surprises you, sits near a clinical threshold, or needs to inform an actual medication dose, that is the point to bring it to a doctor, nurse, or pharmacist rather than act on the number alone. They have the rest of your chart. This page does not.
No. Every calculator on MedCalcTools is for educational purposes only, uses published clinical equations, and is not a substitute for professional medical advice. Consult a qualified healthcare provider for any decision about your health.
Each tool states the exact formula it uses and links to the published source, such as NIDDK and the American Diabetes Association for A1C, or the original Cockcroft and Gault paper and the National Kidney Foundation for creatinine clearance.
No. Calculations run in your browser. The numbers you enter are not sent to a server or saved.
Articles and explanations are written by Naomi Foster, a health writer with Encore Editorial. Content is based on named, published clinical sources rather than personal medical opinion.