Medical Calculators
Anthropometry
Cardiovascular & Renal
Urine Osmolal Gap (Estimated Urinary Ammonium)
Estimates urinary ammonium excretion from measured urine osmolality minus calculated osmoles (2×(Na+K) + BUN/2.8 + glucose/18, with NH4 ~ gap/2) to separate renal from extra-renal causes of normal anion gap metabolic acidosis (raw gap <150 impaired/RTA, >200 favors GI loss).
Duke Treadmill Score
Prognostic risk stratification from a Bruce-protocol exercise treadmill test.
Sodium Correction Infusion-Rate Planner
Plans the IV fluid infusion rate (mL/hr) and total 24-hour volume to correct hyponatremia or hypernatremia at a chosen safe pace, from total body water, serum sodium, the infusate, and a desired sodium change per 24 h (Adrogué-Madias), with division-by-zero and sign-mismatch guards. A closed-system planning aid that tends to underestimate the real rate; recheck serum Na frequently.
TmP/GFR (Renal Phosphate Threshold)
Estimates the renal phosphate threshold from paired serum and spot-urine phosphate and creatinine via the Payne piecewise formula, flagging renal phosphate wasting or retention.
Calcium/Creatinine Clearance Ratio (CCCR)
Distinguishes Familial Hypocalciuric Hypercalcaemia (FHH) from Primary Hyperparathyroidism (PHPT) in a hypercalcaemic patient, using paired 24-h urine and serum calcium and creatinine (<0.01 favours FHH, 0.01–0.02 indeterminate, >0.02 suggests PHPT). One unit selector per pair avoids the mmol-versus-micromol error.
Bicarbonate Deficit
Estimated bicarbonate (mEq) to raise serum HCO3 to an editable target, from k × weight × (target − measured), with an optional severity-adjusted coefficient.
FEUA (Fractional Excretion of Uric Acid)
Estimates the percentage of filtered uric acid excreted in the urine from paired serum and spot-urine uric acid and creatinine; helps differentiate prerenal/volume-depleted states from SIADH, thiazide effect, or renal salt wasting (≤4% prerenal, 4–11% normal, >11% elevated).
DASI (Duke Activity Status Index)
Estimates functional capacity from a 12-item self-report questionnaire of everyday activities, converting the score to an estimated peak oxygen uptake (VO2) and metabolic equivalents (METs). Used in adults to gauge exercise capacity and inform pre-operative and cardiac risk assessment.
Equilibrated Kt/V + Weekly Standard Kt/V
Rebound-corrected eKt/V and frequency-adjusted weekly stdKt/V for any HD schedule (Tattersall / Leypoldt).
SAMe-TT2R2 Score (anticoagulation control on VKA)
Predicts the likely quality of anticoagulation control (time in therapeutic range) for a patient on a vitamin-K antagonist such as warfarin, from six factors: sex, age under 60, more than two of nine listed comorbidities, an interacting drug, current tobacco use (doubled), and non-white race (doubled), for a total of 0 to 8. A score of 0-2 suggests good control (warfarin is reasonable) and a score above 2 suggests poor control (consider a DOAC or intensified monitoring). It rates the quality, not the necessity, of anticoagulation; defer treatment decisions to current guidelines and clinical judgement.
FEMg
Fractional excretion of magnesium; renal Mg wasting vs extrarenal loss in hypomagnesemia.
Mehran Risk Score (Post-PCI CIN)
Predicts contrast-induced AKI risk after PCI from eight weighted factors (hypotension, IABP, CHF, age > 75, anemia, diabetes, contrast volume, eGFR tier); maps to Low/Moderate/High/Very high.
ARC-HBR (Academic Research Consortium High Bleeding Risk)
Classifies patients undergoing PCI as high bleeding risk by counting fourteen major and six minor consensus criteria; high risk if at least one major or at least two minor criteria are met (no numeric score).
Trauma
Emergency & ICU
EGSYS Score
Estimates the likelihood that a transient loss of consciousness was cardiac syncope at initial emergency evaluation from six weighted clinical items (palpitations, abnormal ECG/heart disease, effort, supine onset, autonomic prodromes, precipitating factors); a total of 3 or more favors a cardiac cause.
OESIL Risk Score
Stratifies one-year mortality after syncope in the emergency department from four findings (age > 65, cardiovascular history, absence of prodrome, abnormal ECG); a score of 2 or more flags intermediate-to-high risk.
San Francisco Syncope Rule
Five yes/no CHESS criteria flagging syncope patients at risk of a 7-day serious outcome.
STONE Score (Ureteral Stone Prediction)
Estimates the likelihood of an uncomplicated ureteral stone in an adult with acute flank pain from sex, pain duration, race/ethnicity, nausea/vomiting, and hematuria, reporting a 0–13 total and a Low / Moderate / High likelihood category.
MEWS
Modified Early Warning Score for deterioration in adult ward patients.
Oxygen Delivery / Consumption / Extraction (DO2 / VO2 / O2ER)
Computes arterial and mixed-venous oxygen content, global oxygen delivery (DO2), consumption (VO2), and the oxygen extraction ratio (O2ER) from hemoglobin, saturations, partial pressures, and cardiac output, with optional BSA indexing (DO2I, VO2I), to assess oxygen supply-demand balance in critically ill adults.
Murray Lung Injury Score (LIS)
Grades acute lung injury severity from chest X-ray quadrants of consolidation, PaO2/FiO2 ratio, PEEP, and respiratory system compliance, scoring the sum of assessed components divided by the number used (2–4); 0 no injury, 0.1–2.5 mild-to-moderate, >2.5 severe (ARDS).
Cardiac Power Output (CPO / CPI / CPO-RAP)
Computes cardiac power output (MAP × CO / 451), the right-atrial-pressure-corrected CPO-RAP, and the BSA-indexed cardiac power index (CPI) in heart failure and cardiogenic shock; CPO below 0.6 W marks the cardiogenic-shock range.
Pulmonary Artery Pulsatility Index (PAPi)
Estimates right ventricular function from invasive right-heart catheterization pressures as (PASP − PADP) / RAP, a unitless hemodynamic marker used in cardiogenic shock, advanced heart failure, RV infarction, and mechanical circulatory support evaluation.
PELOD-2 (Pediatric Logistic Organ Dysfunction-2)
Grades multiple organ dysfunction syndrome in critically ill children from ten items across five organ systems (neurologic, cardiovascular, renal, respiratory, hematologic), with several age-specific thresholds; total 0–33 with a derived logistic mortality estimate.
EDACS
Accelerated diagnostic protocol identifying ED chest-pain patients at very low risk of 30-day MACE (EDACS < 16 + negative 0h/2h troponin + no new ECG ischemia).
HACOR Score
Predicts non-invasive ventilation (NIV) failure from heart rate, acidosis (pH), consciousness (GCS), oxygenation (PaO2/FiO2), and respiratory rate; score 0–25 with a high-risk cutoff >5 measured at 1 h of NIV.
Oxygenation Index (OI) / Oxygen Saturation Index (OSI)
Computes the oxygenation index (FiO2 × mean airway pressure × 100 / PaO2) or the SpO2-based oxygen saturation index (valid when SpO2 ≤ 97%) and grades pediatric ARDS severity by PALICC bands.
Pediatric SOFA (pSOFA)
Age-adapted Sequential Organ Failure Assessment for critically ill children: six organ subscores (0–4 each, total 0–24) with age-banded cardiovascular MAP cutoffs and creatinine-only renal criteria.
Ventilator Mechanics Bundle
Computes driving pressure, static and dynamic compliance, airway resistance, and simplified Gattinoni mechanical power from one set of ventilator measurements, flagging dP > 15 cmH2O and MP > 17 J/min.
Perioperative & Thrombosis
Infectious Disease
ISARIC 4C Mortality Score
In-hospital mortality risk for adults admitted with COVID-19 from eight admission variables, stratified into low, intermediate, high, and very high groups.
Shapiro Rule (Blood Culture)
Decides whether an adult ED patient with suspected infection needs a blood culture (Shapiro 2008), with low / intermediate / high bacteremia risk band.
Nugent Score (BV Gram Stain)
Grades a Gram-stained vaginal smear (Lactobacillus, Gardnerella/Bacteroides, and Mobiluncus morphotypes) into a 0–10 score for bacterial vaginosis.
Candida Score (Leon 2006)
Bedside score for non-neutropenic ICU patients colonized with Candida; severe sepsis +2, TPN / surgery / multifocal colonization +1 each, threshold ≥ 3.
DRIP Score
Drug Resistance in Pneumonia risk for community-onset pneumonia; guides empiric extended-spectrum antibiotic choice.
Hepatology
Forns Index
Noninvasive estimate of significant liver fibrosis (F2–F4) in chronic hepatitis C.
PAGE-B Score (HBV HCC risk)
5-year hepatocellular-carcinoma risk in chronic hepatitis B on entecavir/tenofovir from age, sex, and platelets (0–25): ≤9 low, 10–17 intermediate, ≥18 high.
PALBI
Platelet-Albumin-Bilirubin grade — extends ALBI with platelet count for HCC, cirrhosis, variceal bleeding.
Baveno VII (cACLD / CSPH)
Non-invasive Baveno VII criteria: liver stiffness + platelets classify cACLD, the rule-of-five band, and CSPH (ruled out / definite / probable / grey zone), with spleen stiffness resolving the grey zone.
CLIF-C AD
Continuous prognostic score for hospitalised cirrhotic patients with acute decompensation but no ACLF, stratified into Low / Grey zone / High risk.
Pulmonary & Respiratory
VTE-BLEED Score
Six-item bleeding-risk score (anemia, history of bleeding, age ≥ 60, renal dysfunction, active cancer, male-only uncontrolled hypertension) for extended anticoagulation after VTE; ≥ 2 = elevated risk.
Metabolism & Nutrition
Obstetrics
IOM/NASEM 2009 Gestational Weight Gain
Recommended total pregnancy weight gain by pre-pregnancy BMI for singleton or twin, plus the singleton 2nd/3rd-trimester weekly rate.
VBAC Success Probability (Grobman 2021)
Predicts the probability of a successful vaginal birth after cesarean using the 2021 race-neutral MFMU model from maternal age, weight, height, prior cesarean indication, obstetric history, and treated hypertension.
Pediatrics
NIPS (Neonatal Infant Pain Scale)
Neonatal/infant procedural pain from six behavioral signs (cry 0–2, others 0–1; total 0–7).
Yale Observation Scale (YOS)
Bedside rating of how ill a young febrile child appears, from six observed behaviors (cry, reaction to parents, arousal, color, hydration, social response; each 1/3/5, total 6–30): Low ≤ 10 / Intermediate 11–15 / High ≥ 16.
Thompson HIE Score
Severity of hypoxic-ischaemic encephalopathy in term newborns from nine bedside neurological signs (total 0–22): Mild ≤ 10 / Moderate 11–14 / Severe ≥ 15.
Neonatal Therapeutic Hypothermia Eligibility (NICHD)
Three-gate check of whether a newborn meets the NICHD whole-body cooling trial entry criteria for hypoxic-ischemic encephalopathy.
New Ballard Score
Estimates newborn gestational age from 6 neuromuscular and 6 physical maturity signs (canonical chart, several items −1/−2, total −11 to +51; GA = 0.4 × total + 24).
Bacterial Meningitis Score for Children (Nigrovic)
Very-low-risk vs not-low-risk for bacterial meningitis in children with CSF pleocytosis, from 5 predictors (CSF Gram stain +2; CSF ANC ≥ 1,000, CSF protein ≥ 80, blood ANC ≥ 10,000, seizure +1 each; total 0–6): score 0 = very low risk.
PAS (Pediatric Appendicitis Score)
Likelihood of acute appendicitis in children from 8 clinical/lab findings (two physical signs +2, six items +1; total 0–10): Low ≤ 3 / Intermediate 4–6 / High ≥ 7.
Pediatric Appendicitis Risk Calculator (pARC)
Logistic-model probability of appendicitis in children 5–18.9 yr from sex, age, pain duration, four clinical findings, and ANC (entered directly, from WBC, or WBC + neutrophil %).
PRAM Score (Pediatric Asthma)
Acute asthma exacerbation severity in children from five bedside signs (suprasternal/scalene retraction, air entry, wheezing, room-air SpO2; total 0–12, banded mild/moderate/severe).
Neurological Assessment
STESS (Status Epilepticus Severity Score)
Estimates outcome risk in status epilepticus from consciousness, worst seizure type, age, and seizure history (0–6, ≥ 3 unfavorable).
ABCD3-I Score
Stroke risk after TIA with imaging (Merwick 2010), 0–13 points.
Pharmacokinetics
Nursing Assessment
SPPB
Short Physical Performance Battery — balance, 4 m gait, and chair stands, each 0–4, total 0–12 (< 10 suggests a mobility limitation).
STRATIFY Falls Risk
St Thomas's bedside fall-risk screen for elderly inpatients: five items (fall history, agitation, vision, frequent toileting, transfer+mobility = 3 or 4); total 0-5, with 2 or more high risk.
Waterlow Score
Adult pressure-ulcer risk: weighted points across build, skin, sex/age, nutrition, continence, mobility and special risks (10+ at risk, 15+ high, 20+ very high).
CPOT
Critical-Care Pain Observation Tool — 4 observed indicators, total 0–8 (> 2 = significant pain likely).
Rehab / Functional
Drug Dosing
Theophylline / Aminophylline Dosing
Estimates an IV theophylline or aminophylline loading dose and maintenance infusion rate from a target serum concentration, body weight, and population-based clearance, accounting for the salt form.
Potassium Replacement Deficit Estimator
Rough total-body potassium deficit from the measured-to-target serum potassium gap, using the rule that serum K falls about 0.3 mmol/L per 100 mEq lost. Depletional hypokalemia only; not a dosing prescription.
Phenytoin Michaelis-Menten Dose Adjustment
Saturable (Michaelis-Menten) phenytoin dosing: predict the steady-state level from a dose, recommend a dose for a target level, or estimate an individual Vmax from a measured level, accounting for the salt factor.
Lithium Maintenance Dose (Cooper Nomogram)
Predicts the daily lithium-ion maintenance requirement from a single 24-hour serum lithium level measured after one 600 mg lithium carbonate test dose, using the Cooper nomogram equation.
Lab Values
FINDRISC (Finnish Diabetes Risk Score)
Non-invasive questionnaire that estimates 10-year risk of type 2 diabetes from age, BMI, waist circumference, physical activity, diet, blood-pressure medication, prior high glucose, and family history.
Electrolyte Unit Converter (mEq / mmol / mg)
Converts an electrolyte amount between mEq, mmol, and mg for a selected ion (Na, K, Cl, Ca, Mg, HCO3, P, Li) using its atomic weight and valence; phosphorus is reported in mmol/mg only.
Hematology & Oncology
GIPSS (Primary Myelofibrosis)
Genetically inspired prognostic score for primary myelofibrosis from karyotype plus CALR, ASXL1, SRSF2, and U2AF1 Q157 status, sorting patients into four survival risk groups.
CARG Chemotherapy Toxicity Score (Hurria 2011)
Estimates the risk of severe (grade 3–5) chemotherapy toxicity in older adults with cancer from age, cancer type, treatment intensity, two labs, and several geriatric-assessment items.
IMDC / Heng Risk Model (Metastatic RCC)
Counts six clinical and laboratory risk factors in metastatic renal cell carcinoma to sort patients into favorable, intermediate, or poor prognostic groups with associated overall survival.
Glasgow Prognostic Score (GPS) and modified GPS (mGPS)
Combines C-reactive protein and serum albumin into a 0-1-2 inflammation-based prognostic score for patients with cancer, reporting the original GPS and the modified GPS side by side.
Multiple Myeloma ISS (Greipp 2005)
Assigns newly diagnosed multiple myeloma to ISS Stage I, II, or III from serum beta-2 microglobulin and albumin.
DIPSS / DIPSS-Plus (Primary Myelofibrosis Prognosis)
A two-stage prognostic estimate for primary myelofibrosis: grade the dynamic DIPSS clinical score, then refine it with platelet count, transfusion status, and karyotype to report both risk categories together.
HCT-CI (Transplant Comorbidity Index)
A pre-transplant comorbidity index that sums weighted organ-system findings to stratify non-relapse mortality risk before allogeneic hematopoietic cell transplantation, with an optional age adjustment.
Corrected Count Increment (CCI) for Platelet Transfusion
Estimates how well a platelet transfusion raised the count, correcting for body size and dose, and flags an inadequate response that may suggest refractoriness.
NCCN-IPI (Enhanced IPI for DLBCL)
Enhanced 0–8 International Prognostic Index for rituximab-era DLBCL from finer age strata, a normalized LDH ratio, stage, major-site extranodal disease, and ECOG, with four risk groups.
R2-ISS (Second Revision of ISS, Multiple Myeloma)
Weighted prognostic index for newly diagnosed multiple myeloma adding fractional points for ISS stage, elevated LDH, and del(17p), t(4;14), and 1q21+ cytogenetics into four risk groups (R2-ISS I–IV).
CNS-IPI (CNS Relapse Risk in DLBCL)
Six-factor 0–6 index for central nervous system relapse risk in DLBCL from age, LDH, ECOG, stage, extranodal sites, and kidney/adrenal involvement, with three risk groups.
Cairo-Bishop TLS Criteria & Grade
Original Cairo-Bishop 2004 tumor lysis syndrome: laboratory TLS (≥ 2 of uric acid, potassium, phosphorus, calcium), clinical TLS, and grade 0–5.
Toxicology
Fomepizole Dosing (with Hemodialysis)
Weight-based fomepizole (4-MP) dosing for ethylene glycol / methanol poisoning from the FDA Antizol label: full standard schedule plus the every-4-hour hemodialysis adjustments at the beginning (≥ 6 h rule), during, and completion (< 1 h / 1-3 h half / > 3 h full) of HD.
Digoxin Immune Fab (DigiFab)
Estimates starting digoxin immune Fab vials for digoxin/digitoxin toxicity from amount ingested, serum level + weight, or empiric (FDA PI formulas; < 20 kg switches to a mg-based dose).
Naranjo ADR Probability Scale
Causality assessment for a suspected adverse drug reaction: ten standardized questions (timing, dechallenge/rechallenge, alternative causes, dose-response, drug levels, objective confirmation) banded doubtful / possible / probable / definite.
Rheumatology
Modified Rodnan Skin Score (mRSS)
Sum of skin-thickness grades (0-3) across 17 body sites (max 51) to quantify cutaneous involvement in systemic sclerosis; a continuous severity / monitoring index, not a diagnostic or classification criterion.
2016 ACR/EULAR Primary Sjogren Syndrome Classification Criteria
Entry- and exclusion-gated weighted classification for primary Sjogren syndrome: five objective items (biopsy focus score and anti-SSA/Ro +3 each; ocular staining, Schirmer, and salivary flow +1 each) summed to a 0–9 total; classify at ≥ 4 once both gates pass.
Fibromyalgia 2016 ACR Diagnostic Criteria
Applies the 2016 revision of the ACR fibromyalgia criteria: records the Widespread Pain Index over nineteen body areas and the Symptom Severity Scale, checks generalized pain and ≥ 3 month duration, and reports whether all criteria are met along with the combined Fibromyalgia Symptom (FS) scale.
2022 ACR/EULAR ANCA-Associated Vasculitis
Computes the 2022 ACR/EULAR weighted classification scores for GPA, MPA, and EGPA at once from one set of clinical, ANCA, imaging, and biopsy findings, reporting whether each disease reaches its threshold (≥ 5, ≥ 5, ≥ 6).
2022 ACR/EULAR Giant Cell Arteritis Classification Criteria
Entry-gated, weighted GCA classification (age ≥ 50 plus established large-vessel vasculitis gate); composite-OR biopsy/ultrasound (+5) and ESR/CRP (+3) each scored once; classify at total ≥ 6.
2013 ACR/EULAR Systemic Sclerosis Classification Criteria
Entry-gated, weighted SSc classification: bilateral skin thickening proximal to the MCP joints is sufficient on its own, otherwise the highest weight in each category is summed (PAH/ILD and autoantibodies capped); classify at total ≥ 9.
ESSDAI (EULAR Sjögren's Syndrome Disease Activity Index)
Physician-scored systemic activity in primary Sjögren's syndrome: twelve organ-system domains, each weighted and scored by activity level, summed to a single 0–123 score banded Low / Moderate / High.
2019 EULAR/ACR SLE Classification Criteria
Entry-gated, weighted SLE classification: a positive ANA gates ten domains, each scored at its single highest item; classify at total ≥ 10 with at least one clinical criterion.
ASDAS-CRP / ASDAS-ESR (Axial Spondyloarthritis)
Axial Spondyloarthritis Disease Activity Score: four patient-reported components plus CRP (preferred) or ESR, with variant-specific coefficients, banded Inactive/Low/High/Very high.
SLEDAI-2K (SLE Disease Activity Index 2000)
Weighted sum of 24 clinical and laboratory descriptors of systemic lupus activity (8/4/2/1 pts, no caps, max 105), banded No activity / Mild / Moderate / High / Very high.
2015 ACR/EULAR Gout Criteria
Classifies gout via an entry criterion, an MSU-crystal sufficient criterion, and an additive score across eight domains (pattern, characteristics, time course, tophus, serum urate, synovial fluid, imaging), with ≥ 8 of 23 points classifying.
DAPSA (Psoriatic Arthritis)
Disease Activity Index for Psoriatic Arthritis: unweighted sum of tender (68) and swollen (66) joint counts, patient pain and global VAS, and CRP (mg/dL), banded Remission/Low/Moderate/High.
Gastroenterology
ABC Score (GI Bleeding 30-day Mortality)
Predicts 30-day mortality in acute upper or lower GI bleeding from age, urea, albumin, creatinine, mental status, cirrhosis, malignancy, and ASA grade; bands low/medium/high.
Simple Clinical Colitis Activity Index (SCCAI)
Symptom-based 0–19 score for tracking ulcerative colitis activity from clinical features alone, without labs or endoscopy.
Pancreatitis Activity Scoring System (PASS)
Additive acute-pancreatitis activity score from organ failure, SIRS, pain, opioid dose, and feeding tolerance, for serial tracking over time.
Crohn's Disease Activity Index (CDAI)
Weighted 8-term index of Crohn disease clinical activity (stools, pain, wellbeing, complications, antidiarrheal, mass, hematocrit, weight); bands remission/mild/moderate/severe.
Travis / Oxford Day-3 Criteria
Acute severe ulcerative colitis: predicts IV-corticosteroid failure on day 3 (>8 stools, or 3–8 stools with CRP > 45 mg/L) to flag rescue therapy or colectomy.
Mayo Score / Partial Mayo Score
Ulcerative colitis activity: full Mayo (0–12, needs endoscopy) and endoscopy-free Partial Mayo (0–9) with remission/mild/moderate/severe bands.
Comorbidity / Prognosis
FRAIL Scale
Five-item frailty screen (Fatigue, Resistance, Ambulation, Illnesses, Loss of weight) sorting older adults into robust, pre-frail, or frail (Morley 2012).
Substance Use / Withdrawal
Anesthesia & Pain
SORT 30-Day Mortality
Surgical Outcome Risk Tool logistic estimate of 30-day mortality after inpatient non-cardiac, non-neurological surgery from six preoperative factors.