Twelve medical calculators. One idea: understand, don't diagnose.
Real, published formulas from across medicine — general medicine, cardiology, nephrology, pediatrics, OB/GYN, endocrinology, nutrition, pulmonology, anesthesiology, critical care, emergency medicine, and pharmacology.
⚖️ General / Internal Medicine
❤️ Cardiology
🫘 Nephrology
🧒 Pediatrics
🤰 OB/GYN
🩸 Endocrinology
🍽️ Nutrition
🫁 Pulmonology
⚗️ Anesthesiology
🏥 ICU / Critical Care
🚑 Emergency Medicine
💊 Pharmacology
Why "educational only"?
Real clinical decisions need a clinician who has examined you, knows your full history, and can order the right tests. These calculators use the same published formulas doctors reference — but a formula without a physical exam, lab context, and clinical judgment is a starting point for a conversation, never a diagnosis or a treatment plan. See the guide for every formula's source.
⚖️ BMI Calculator
Body mass index from height and weight.
BMI Calculator
What BMI does and doesn't tell you
Body mass index is a quick screening ratio of weight to height, standardized by the WHO and CDC for population-level tracking. It's a useful starting point, but it doesn't distinguish muscle from fat, doesn't account for where fat is distributed, and can misclassify very muscular or very lean individuals.
When to look further
A high or low BMI is a reason to discuss body composition, waist circumference, and overall health markers with a doctor — not a diagnosis on its own.
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❤️ Cardiovascular Risk Factors
Tally your major AHA-recognized heart disease risk factors.
Cardiovascular Risk Factors
Check every factor that applies to you. This counts major AHA-recognized risk factors — it is not a percentage risk score.
Why this counts factors instead of giving a percentage
The formal tool doctors use — the ACC/AHA Pooled Cohort Equations — combines age, sex, cholesterol, blood pressure, and race-stratified coefficients through a fairly complex statistical model to produce a 10-year risk percentage. Reproducing that model imprecisely would output a confident-looking number that could be meaningfully wrong. This tool instead tallies the major risk factors that clinicians look at, which is honest about what it actually knows.
What to do with this
If several factors apply to you, that's a reason to ask your doctor for an actual ASCVD risk calculation and a conversation about prevention — not a reason to self-diagnose your heart disease risk.
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🫘 eGFR (Kidney Function)
Estimated glomerular filtration rate, CKD-EPI 2021.
eGFR (CKD-EPI 2021)
The current standard for kidney function estimation
The 2021 CKD-EPI creatinine equation is the race-free formula now recommended by the National Kidney Foundation and American Society of Nephrology, replacing an earlier version that used a race-based coefficient. It estimates how well your kidneys filter blood based on a blood creatinine test, your age, and sex.
What affects accuracy
eGFR from creatinine can be thrown off by muscle mass, diet, certain medications, and acute illness. A single reading, especially outside a lab context your doctor can interpret, is not a kidney disease diagnosis.
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🧒 Pediatric Weight-Based Dosing
mg/kg dosing with an adult-equivalent safety cap.
Pediatric Weight-Based Dosing
A generic mg/kg calculator with an optional adult-equivalent cap. This does not know which medication you mean — always use the specific drug's approved pediatric dosing, and confirm with a pharmacist or physician.
How weight-based pediatric dosing works
Many pediatric medications are dosed in milligrams per kilogram of body weight rather than a flat adult dose, since children's body composition and drug metabolism differ substantially from adults'. An adult-equivalent maximum is often applied as a ceiling once a child's calculated dose would exceed what's given to an adult.
This tool is generic on purpose
It doesn't know which drug you're dosing — the correct mg/kg figure, dosing frequency, and maximum vary by medication and by the child's age and condition. Always use the specific drug's approved pediatric dosing reference, and have a pharmacist or physician confirm before giving any medication to a child.
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🤰 Pregnancy Due Date
Naegele's rule — estimated due date and gestational age.
Pregnancy Due Date (Naegele's Rule)
How Naegele's rule works
Naegele's rule estimates a due date as 280 days (40 weeks) from the first day of your last menstrual period, assuming a standard 28-day cycle with ovulation around day 14. It's the traditional bedside estimate still used as a starting point in most pregnancies.
Why it's an estimate
Actual delivery commonly happens anywhere from 37 to 42 weeks, and cycle length varies between individuals. An early ultrasound is more precise than LMP-based dating alone — this calculator is a starting-point estimate, not a confirmed due date.
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🩸 HbA1c to Average Glucose
ADAG study conversion from HbA1c % to eAG.
HbA1c to Average Glucose (ADAG)
Connecting a lab value to something intuitive
HbA1c reflects average blood glucose over roughly the past 2-3 months, but it's reported as a percentage that isn't intuitive to compare against day-to-day glucose meter readings. The ADAG study derived a linear formula converting HbA1c into an estimated average glucose (eAG) in the same units a glucose meter uses.
What the categories mean
The standard ADA reference ranges (below 5.7% normal, 5.7-6.4% prediabetes, 6.5%+ diabetes) are shown for context — a single HbA1c value should always be interpreted by a clinician alongside symptoms and other labs.
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🍽️ Daily Calorie Needs
Mifflin-St Jeor BMR plus activity level.
Daily Calorie Needs (Mifflin-St Jeor)
Why Mifflin-St Jeor
The Mifflin-St Jeor equation is widely considered the most accurate widely-available formula for estimating basal metabolic rate (BMR) — the calories your body burns at rest — and is the equation most commonly recommended by dietetics organizations over older formulas like Harris-Benedict. Multiplying BMR by an activity factor estimates total daily energy expenditure (TDEE).
Individual variation is real
This is a population-average estimate — actual metabolic rate varies by as much as 10-15% between individuals with identical stats. Use it as a starting point and adjust based on your own results over a few weeks, not as an exact prescription.
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🫁 Vital Signs Reference
Compare respiratory rate, SpO2, and heart rate to typical adult ranges.
Vital Signs Reference
Compares your numbers to typical adult reference ranges — not a diagnosis, and normal ranges vary by individual, age, and condition.
What "normal" ranges mean
These reference ranges (respiratory rate 12-20 breaths/min, oxygen saturation 95-100%, heart rate 60-100 bpm) reflect typical resting values for a healthy adult, drawn from standard clinical references. They're a useful sanity check, not a diagnostic threshold.
Context always matters
A trained athlete can have a healthy resting heart rate well below 60. A single vital sign outside the typical range, especially without the context of how you're feeling and your baseline, is not by itself a medical emergency or a diagnosis — trends and how you feel matter more than one number.
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⚗️ Ideal Body Weight
Devine formula — commonly used for medication dosing.
Ideal Body Weight (Devine)
Why "ideal" body weight exists as a concept
The Devine formula was originally developed in 1974 specifically to help calculate medication doses more accurately — some drugs are dosed based on an estimated "ideal" weight rather than actual body weight, particularly for people whose actual weight is much higher or lower than average for their height.
Not a personal weight goal
Despite the name, this number isn't a healthy weight target for any individual — body composition, muscle mass, and frame size all matter. Its real, narrow use is in specific medical dosing calculations performed by clinicians and pharmacists.
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🏥 SIRS Criteria Checker
The four standard systemic inflammatory response criteria.
SIRS Criteria Checker
The 4 standard Systemic Inflammatory Response Syndrome criteria. Meeting 2 or more is the standard SIRS threshold — this is a checklist reference, not a diagnosis of sepsis or infection.
What SIRS criteria are for
Systemic Inflammatory Response Syndrome (SIRS) criteria are four simple, objective measurements (temperature, heart rate, respiratory rate, white blood cell count) that flag when the body may be mounting a significant inflammatory response — from infection, trauma, pancreatitis, or other causes. Meeting 2 or more criteria is the standard threshold clinicians use as a prompt for further evaluation.
Not a sepsis diagnosis
SIRS criteria are sensitive but not specific — many non-infectious conditions (and even vigorous exercise) can trigger them. Meeting the threshold is a signal to seek medical evaluation, not a diagnosis of infection or sepsis on its own.
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🚑 Wells DVT Score
Simplified two-level Wells criteria for deep vein thrombosis.
Wells DVT Score
The simplified two-level Wells score for deep vein thrombosis. A score of 2 or more is classified "likely" — this changes how urgently someone should be evaluated, not whether they have a DVT.
How the Wells score is used clinically
The Wells DVT score is a structured way to combine several clinical findings — swelling, tenderness, risk factors like recent surgery or cancer — into a "likely" or "unlikely" classification that guides how urgently someone should be tested for deep vein thrombosis. It was validated specifically for this purpose, alongside D-dimer blood testing and ultrasound.
This requires a physical exam
Several criteria (localized tenderness, calf swelling measured against the other leg, pitting edema) require an actual physical examination to assess accurately — you can't reliably self-assess most of these. This tool is for understanding how the score works, not for scoring yourself instead of being examined.
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💊 Creatinine Clearance
Cockcroft-Gault formula — used for renal drug dose adjustment.
Creatinine Clearance (Cockcroft-Gault)
Why Cockcroft-Gault is still used
Even though eGFR equations like CKD-EPI are now preferred for classifying chronic kidney disease, the Cockcroft-Gault formula (1976) remains the standard reference for adjusting medication doses in reduced kidney function, because most drug dosing studies and package inserts were validated against it specifically.
Weight matters here
Unlike CKD-EPI, Cockcroft-Gault uses actual body weight directly in the formula (in some clinical contexts an adjusted or ideal weight is used instead for people who are significantly over or underweight) — a pharmacist adjusting a real prescription accounts for this. This tool illustrates the formula, not a dosing decision.
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Formulas & sources
Every equation used in MedKit, with its clinical source.
| Tool | Formula / source |
|---|---|
| BMI | weight(kg) / height(m)² — WHO/CDC standard |
| Cardiovascular Risk Factors | AHA/ACC major modifiable + non-modifiable ASCVD risk factor tally |
| eGFR | CKD-EPI 2021 race-free creatinine equation (NKF/ASN Task Force, 2021) |
| Pediatric Dosing | Generic mg/kg weight-based dosing with adult-equivalent cap |
| Pregnancy Due Date | Naegele's rule — LMP + 280 days |
| HbA1c to Average Glucose | eAG(mg/dL) = 28.7 × HbA1c − 46.7 — ADAG Study, Diabetes Care 2008 |
| Daily Calorie Needs | Mifflin-St Jeor equation (1990) + activity multiplier |
| Vital Signs Reference | Standard adult reference ranges (respiratory rate, SpO2, heart rate) |
| Ideal Body Weight | Devine formula (1974) |
| SIRS Criteria | Bone RC et al. 1992 consensus definition (4-criterion checklist) |
| Wells DVT Score | Simplified two-level Wells criteria for deep vein thrombosis |
| Creatinine Clearance | Cockcroft-Gault formula (1976) |
Please read this
- Educational tool only. Not medical advice, not a diagnosis, and not a substitute for a qualified healthcare professional. Always consult a doctor for any health decision. These formulas are real and published, but medicine is practiced with a physical exam, a full history, lab context, and clinical judgment — none of which a calculator has. If something here concerns you, the right next step is always a conversation with a qualified healthcare professional, not a decision based on this site.