Free Medical Calculators – BSA, BMI & More | Medinzo

Free, easy-to-use medical calculators built for patients, doctors, pharmacists, nurses, and paramedical staff — evidence-based and simple to understand.

Body Surface Area (BSA) Calculator
Calculate BSA using the Mosteller formula — for adults and children.
BMI Calculator
Calculate your Body Mass Index in kg and cm or kg with feet and inches — includes your weight category and healthy weight range.
Calorie Calculator (BMR & TDEE)
Calculate your BMR and TDEE using the Mifflin-St Jeor formula — includes daily calorie targets for weight loss or gain.
eGFR Calculator (CKD-EPI & Schwartz)
Calculate kidney function (eGFR) using CKD-EPI 2021 for adults and Bedside Schwartz for children.
HbA1c Calculator (A1C to Average Glucose)
Convert HbA1c % to average blood sugar in mg/dL and mmol/L, or to mmol/mol — includes a conversion chart and normal ranges.
Age Calculator (Exact Age from Date of Birth)
Find your exact age in years, months and days, or on any date you choose — includes age in weeks, days and hours, and your next birthday.
More calculators coming soon

Which Calculator Should I Use?

I want to know my…Use
Weight category and healthy weight rangeBMI Calculator
Body surface area in m²BSA Calculator
Daily calorie needs (BMR and TDEE)Calorie Calculator
Kidney function (eGFR)eGFR Calculator
Average blood sugar from an HbA1c resultHbA1c Calculator
Exact age, or age on a particular dateAge Calculator

How to Use Our Medical Calculators

  1. Pick a calculator from the list above.
  2. Enter your values with the correct units, such as kg or lb, cm or ft/in, mg/dL or mmol/L.
  3. Press Calculate and read the result together with the explanation on the same page.
  4. Discuss important results with your doctor or pharmacist before acting on them.

Built to Be Clear and Evidence-Based

Every Medinzo calculator page pairs the tool with plain-language explanations, the formula behind the result, notes on its limits and a list of sources. The aim is that a patient can understand the number and a healthcare professional can check how it was worked out.

The pages are made for mobile phones first, use simple controls, and follow a consistent layout so that every calculator feels familiar.

Medical disclaimer: These calculators are for general education and do not replace professional medical advice, diagnosis or treatment. Do not change a medicine or dose based on a calculator result. Always consult a qualified doctor or pharmacist.

Medical Calculator FAQs

Are Medinzo medical calculators free to use?

Yes. All calculators on this page are free to use, with no sign-up needed.

Can I use these calculators to diagnose a condition or choose a treatment?

No. The calculators give estimates and conversions to support understanding. They do not diagnose disease or replace the judgement of a doctor, pharmacist or other qualified healthcare professional. Never change a medicine or dose based on a calculator result alone.

Where do the formulas come from?

Each calculator page explains the formula it uses and lists its sources, so you can check how the result is worked out.

Are there calculators that work for children?

Yes. The BSA calculator works for adults and children, the eGFR calculator includes the Bedside Schwartz equation for children, and the Age Calculator shows age in months and weeks. Children's medicine doses should always come from a doctor or pharmacist.

Do the calculators store my personal health values?

Medinzo calculators are designed not to store the personal health values you type in. Even so, avoid entering your name or other identifying details.

Scroll to Top