Health: 131 free medical calculators & clinical scores

This is the biggest single release maratool has shipped. The new Health category collects the calculators and clinical scores clinicians actually reach for at the bedside — kidney function, liver prognosis, sepsis screening, stroke and bleeding risk, ICU severity, oncology performance status, and much more.

Every additive score and formula was implemented from its original paper or guideline, unit-tested against published worked examples, and ships with a medical disclaimer, references, and an FAQ. Here is everything that is now live, by area.

Anthropometric

• BMI Calculator — body mass index, classification, and body surface area.
• Ideal Body Weight — Devine, Robinson, Miller, and Hamwi formulas.
• Estimated Blood Volume — total blood volume by the Nadler formula.

Cardiology

• Mean Arterial Pressure (MAP) — from systolic and diastolic pressure.
• Corrected QT (QTc) — Bazett, Fridericia, Framingham, and Hodges.
• Friedewald LDL Cholesterol — LDL from total cholesterol, HDL, and triglycerides.

Renal

• CKD-EPI eGFR (2021) — race-free creatinine equation.
• Cockcroft-Gault — creatinine clearance for drug dosing.
• MDRD GFR — 4-variable estimate.
• FENa — prerenal vs intrinsic AKI.
• FEUrea — AKI workup on diuretics.
• Urine Protein-to-Creatinine Ratio — spot-sample proteinuria.
• Bicarbonate Deficit — replacement dose in metabolic acidosis.

Electrolytes

• Serum Osmolality — from sodium, glucose, and BUN.
• Calcium Correction for Albumin — corrected total calcium.
• Sodium Correction for Hyperglycemia — Katz / Hillier.
• Total Iron Deficit (Ganzoni) — IV iron replacement dose.

Endocrine

• Estimated Average Glucose (eAG) — HbA1c to mg/dL and mmol/L.
• Transferrin Saturation (TSAT) — from serum iron and TIBC.

Hepatology

• Serum-Ascites Albumin Gradient (SAAG) — portal vs non-portal ascites.
• Lille Model — day-7 steroid response in alcoholic hepatitis.

Ventilation

• Ideal PaO₂ by Age — expected normal PaO₂.
• PaO₂/FiO₂ Ratio — ARDS severity by Berlin criteria.
• SpO₂/FiO₂ Ratio — non-invasive ARDS surrogate.

Obstetric

• Gestational Age by LMP — Naegele rule and due date.
• Gestational Age by Ultrasound — from biometry.

Pediatric

• APGAR Score — newborn assessment at 1 and 5 minutes.
• Pediatric Glasgow Coma Scale — GCS adapted for infants and children.
• Pediatric ETT Size — tube size and depth by age.
• Pediatric Infusion (mcg/kg/min) — drug infusion rate.
• Pediatric Infusion (mg/kg/hour) — drug infusion rate.
• Finnegan Neonatal Abstinence Score — NAS severity.
• Raimondi Coma Scale — pediatric consciousness.
• Rodwell Neonatal Sepsis Score — hematologic sepsis screen.
• Capurro Gestational Age (Somatic) — newborn maturity.
• Capurro Gestational Age (Neurological) — newborn maturity.

Drug dosing

• Benzodiazepine Equivalence — diazepam, lorazepam, alprazolam, and more.
• Corticosteroid Conversion — prednisone-equivalent dosing.
• Opioid Conversion (MME) — morphine milligram equivalents.
• RSI Dose Calculator — weight-based induction and paralytic doses.
• Phenytoin Level Correction — Sheiner-Tozer for albumin and renal function.

Infusion

• Drops/min ↔ mL/hour — IV drip rate conversion.
• mcg/kg/min ↔ mL/hour — vasoactive drug infusion.

Trauma

• Parkland Burn Formula — fluid resuscitation for burns.

Screening

• CAM-ICU — delirium assessment in critically ill patients.
• GINA Asthma Control (2025) — well / partly / uncontrolled.
• CAGE — 4-item alcohol use disorder screen.
• MMSE — 30-point cognitive screen.
• Fagerström Test — nicotine dependence severity.

Scales

• FOUR Score — coma assessment (0–16).
• Fisher Scale — SAH vasospasm risk by CT.
• Glasgow Coma Scale with Pupils (GCS-P) — GCS adjusted for pupil reactivity.
• Lawton IADL Scale — instrumental activities of daily living.
• Ramsay Sedation Scale — sedation level 1–6.
• RASS — Richmond Agitation-Sedation Scale.
• SAS (Riker) — Sedation-Agitation Scale.
• CCS Angina Grade — Canadian Cardiovascular Society class.
• Aldrete Recovery Score — post-anesthesia recovery.

Prognosis

• ECOG Performance Status — oncology functional status (0–5).
• Karnofsky Performance Status — function 0–100.
• Palliative Performance Scale (PPS) — hospice prognosis.
• Tokuhashi Score — spinal metastasis prognosis.
• Tomita Score — surgical strategy for spinal metastasis.
• Palliative Prognostic Score (PaP) — 30-day survival.
• Palliative Prognostic Index (PPI) — terminal-cancer survival.

Clinical scores

Sixty-five validated clinical scores, grouped by what you are reasoning about.

Cardiac risk & ACS

• CHADS2 and CHA2DS2-VASc — AF stroke risk.
• HAS-BLED — bleeding risk on anticoagulation.
• HEART Score — chest-pain MACE risk.
• TIMI (STEMI) and TIMI (NSTEMI/UA) — ACS risk.
• GRACE — ACS in-hospital and 6-month mortality.
• CRUSADE — major bleeding after NSTEMI.
• Lee RCRI, Detsky, and Goldman — preoperative cardiac risk.
• GWTG-HF — acute heart-failure mortality.
• NYHA Class — heart-failure functional class.
• Framingham Risk Score — 10-year CHD risk.

Stroke & neurology

• ABCD2 — stroke risk after TIA.
• ASPECTS — early ischemic change on stroke CT.
• NIHSS — stroke severity scale.
• RoPE Score — PFO-related cryptogenic stroke.

VTE & pulmonary embolism

• Wells (PE) and Wells (DVT) — pretest probability.
• PERC Rule — safely exclude PE.
• PESI and Simplified PESI — PE 30-day mortality.
• Padua Prediction — VTE risk in medical inpatients.
• Caprini — surgical VTE risk.
• Khorana — chemotherapy-associated VTE.

Sepsis & critical care

• qSOFA and SOFA — sepsis screening and organ dysfunction.
• APACHE II — ICU severity and predicted mortality.
• NEWS 2 — clinical deterioration.
• SIC Score — sepsis-induced coagulopathy.
• CPIS — ventilator-associated pneumonia.
• Candida Score — invasive candidiasis risk in ICU.

Pneumonia & infection

• CURB-65 and PSI / PORT — community-acquired pneumonia severity.
• Modified Centor — strep pharyngitis probability.

Gastroenterology & hepatology

• Child-Pugh and MELD / MELD-Na — cirrhosis prognosis.
• Maddrey Discriminant Function and Lille Model — alcoholic hepatitis.
• FIB-4 and NAFLD Fibrosis Score — non-invasive fibrosis.
• Mayo Score and UCEIS — ulcerative colitis activity.
• Harvey-Bradshaw Index and CDAI — Crohn's disease activity.
• Ranson Criteria, BISAP — acute pancreatitis severity.
• AIMS65 and Rockall — upper GI bleeding mortality.

Surgery & trauma

• Injury Severity Score (ISS) — anatomical trauma severity.
• TASH Score — massive transfusion prediction.
• Alvarado Score — appendicitis probability.

Oncology & hematology

• GELF Criteria — follicular lymphoma tumor burden.
• R-ISS — multiple myeloma staging.
• MASCC Risk Index — low-risk febrile neutropenia.

Rheumatology & dermatology

• DAS-28 CRP and DAS-28 ESR — rheumatoid arthritis activity.
• SCORAD — atopic dermatitis severity.
• PASI — psoriasis area and severity.

Other

• DKA Severity — diabetic ketoacidosis grading.
• Malignant Hyperthermia Score — clinical grading scale.
• Bishop Score — cervical ripening for labor induction.
• San Francisco Syncope Rule — serious-outcome risk.
• Pediatric Dehydration Severity — guides rehydration.
• Pack-Year Calculator — cumulative smoking exposure.

And one more

COVID-19 Severity stratifies SARS-CoV-2 illness across the clinical spectrum from asymptomatic to critical, with the general management direction for each tier.

How these were built

Each calculator implements the canonical formula from its source paper or guideline — Cockcroft & Gault 1976, the 2021 CKD-EPI equation, Kamath's MELD, the Sepsis-3 SOFA/qSOFA, Knaus' APACHE II, the NCEP ATP III Framingham tables, and so on. The pure formula functions are unit-tested against published worked examples, the simpler categorical scores were validated side-by-side against an established reference, and every page carries its references and a clinical-use disclaimer.

A handful of complex regression models that require proprietary or large published coefficient sets (for example EuroSCORE II, the PREVENT equations, and pediatric BMI/BP percentile tables) are intentionally not shipped yet, rather than approximated — an inaccurate medical calculator is worse than none.

These tools are for licensed healthcare professionals and do not replace clinical judgment. All of maratool.com is free, runs in your browser, and needs no sign-up. Browse everything in the Health category, and if a formula looks off, tell me.