General Medicine Calculators

50 calculators & risk scores

Browse 50 General Medicine clinical calculators and risk scores used in everyday UK practice. Every tool runs entirely in your browser — enter the values and get instant scoring, colour-coded interpretation bands and a link to the underlying guideline or publication. ClinCalc Pro is free, needs no sign-up, and is built for working clinicians.

These general medicine tools span Anthropometry, Electrolytes, VTE Prevention, Nutrition, Prognosis, Diagnosis and more.

Body Mass Index (BMI)

Calculates BMI from weight and height. WHO obesity classification. NICE: for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background, overweight is BMI 23–27.4 and obesity 27.5 or above.
Body Surface Area (Mosteller)

Calculates BSA using Mosteller formula. Used for chemotherapy dosing and cardiac index.
Ideal Body Weight (Devine)

Estimates ideal body weight using Devine formula. Used for drug dosing and ventilator settings.
Adjusted Body Weight

Calculates adjusted body weight for obese patients: IBW + 0.4×(Actual - IBW).
Calculated Serum Osmolality

Calculates serum osmolality. Osmol gap = Measured − Calculated (>10 suggests toxic alcohol ingestion).
Padua Prediction Score (VTE Risk)

Assesses VTE risk in medical inpatients to guide pharmacological thromboprophylaxis.
MUST Score (Malnutrition Screening)

Malnutrition Universal Screening Tool. Identifies patients at risk of malnutrition.
Charlson Comorbidity Index (CCI)

Predicts 10-year mortality based on comorbid conditions. Widely used for risk adjustment in research and clinical decision-making.
Clinical Frailty Scale (CFS)

Rockwood Clinical Frailty Scale — 9-point clinical judgment tool for frailty. Predicts adverse outcomes and guides treatment decisions.
4AT — Rapid Assessment for Delirium

Rapid bedside screening tool for delirium and cognitive impairment. Does not require special training.
Braden Scale for Pressure Ulcer Risk

Six-factor pressure ulcer risk assessment. Scores range from 6 (highest risk) to 23 (lowest risk).
LDL Cholesterol — Friedewald Equation

Calculates LDL from total cholesterol, HDL, and triglycerides. LDL = TC − HDL − (TG / 2.2). Not valid if TG >4.5 mmol/L.
Morse Fall Scale

Six-item validated tool for identifying patients at risk of falls in hospital settings.
Timed Up and Go (TUG) Test

Functional mobility test: time taken to rise from chair, walk 3 metres, return and sit. Predicts fall risk and functional independence.
HOSPITAL Score for 30-Day Readmission

Predicts 30-day potentially avoidable hospital readmissions using seven variables available at discharge.
LACE Index for Readmission Risk

Predicts 30-day unplanned readmission or death after hospital discharge using Length of stay, Acuity, Comorbidity, and Emergency visits.
Confusion Assessment Method (CAM)

Standardised diagnostic algorithm for delirium detection. Requires features 1+2 PLUS either 3 or 4 for positive diagnosis.
Waterlow Pressure Ulcer Risk Score

Waterlow pressure ulcer risk score (1985, revised 2005): build, skin, sex and age, malnutrition screening, continence, mobility and special risks. 10+ at risk, 15+ high risk, 20+ very high risk.
6-Minute Walk Test (6MWT) Reference Values

Assesses functional exercise capacity. Calculates predicted 6MWT distance and interprets measured distance as percentage predicted.
Mini-Mental State Examination (MMSE)

30-point questionnaire assessing orientation, registration, attention, recall, and language. Standard cognitive screening tool.
MoCA — Montreal Cognitive Assessment

30-point cognitive screening tool, more sensitive than the MMSE for mild cognitive impairment (Nasreddine 2005: cut-off 26 detected 90% of MCI and 100% of mild Alzheimer's disease).
FAST Scale for Alzheimer's Dementia

Functional Assessment Staging Test (FAST) — tracks functional decline in Alzheimer's disease from normal to severe. Used in care planning and prognostication.
Palliative Performance Scale (PPS)

Measures functional status and prognosis in palliative care patients. Modified Karnofsky scale adapted for end-of-life care. Score 10–100% in 10% increments.
Charlson Comorbidity Index (CCI) — Detailed

Charlson comorbidity index with age adjustment: 19 weighted conditions plus 1 point per decade from age 50 (maximum 4), with the estimated 10-year survival.
Number Needed to Treat (NNT) / Number Needed to Harm (NNH)

Calculates NNT or NNH from event rates in treatment and control groups. Fundamental EBM tool for communicating treatment effectiveness.
Sensitivity / Specificity / PPV / NPV Calculator

Calculates sensitivity, specificity, PPV, and NPV from a 2x2 contingency table. Essential for evaluating diagnostic tests.
Likelihood Ratio and Post-Test Probability Calculator

Converts pre-test probability to post-test probability using positive or negative likelihood ratios. Key tool for Bayesian clinical reasoning.
Elixhauser Comorbidity Index

van Walraven point version of the Elixhauser comorbidity measures (21 of 30 conditions carry weight). Designed for in-hospital mortality risk adjustment of administrative data.
Palliative Prognostic Score (PaP Score)

Predicts 30-day survival probability in advanced cancer patients using dyspnoea, anorexia, Karnofsky Performance Status, WBC, lymphocyte percentage, and clinician estimate.
DNACPR / ReSPECT Decision Support Tool

Supports DNACPR and ReSPECT conversations. CPR decisions are made by the senior responsible clinician with the patient (or, if the patient lacks capacity, those close to them) using the BMA / Resuscitation Council UK / RCN guidance — there is no validated points score.
LDL Cholesterol — Friedewald Equation

Calculates LDL cholesterol using the Friedewald equation when direct LDL not available. LDL = Total Cholesterol − HDL − (Triglycerides ÷ 2.2) in mmol/L. Valid only when triglycerides <4.5 mmol/L. Inaccurate in hypertriglyceridaemia, type III hyperlipidaemia, or non-fasting samples.
Neutrophil-to-Lymphocyte Ratio (NLR)

Simple inflammatory index calculated from FBC. Elevated NLR (>3.5–5) indicates systemic inflammation, infection, or stress. Useful prognostic marker in sepsis, cancer, cardiovascular disease, and COVID-19. Low NLR (<1) may suggest immunosuppression or viral illness.
Benzodiazepine Conversion Calculator

Converts equivalent doses between benzodiazepines based on diazepam equivalency. Used for cross-tapering, dose reduction, and management of benzodiazepine dependence. Equivalences follow the Ashton Manual: each listed dose is approximately equivalent to diazepam 10 mg (adults). Note: equivalencies are approximate, vary between individuals and between sources, and require clinical judgement. Children: use a children's formulary.
Carpal Tunnel Syndrome-6 (CTS-6) Diagnostic Tool

CTS-6 (Graham 2006): six weighted clinical criteria for carpal tunnel syndrome — numbness in the median territory, nocturnal numbness, thenar atrophy or weakness, Phalen test, loss of 2-point discrimination and Tinel sign. Score 0–26; ≥ 12 means CTS is likely.
Roth Score for Hypoxia Screening

Bedside screening test for low oxygen levels: the patient counts aloud from 1 to 30 as fast as possible in a single breath. A low count suggests hypoxaemia. Small studies disagree on its accuracy, so it never replaces pulse oximetry.
Wells DVT Score

Pre-test probability score for deep vein thrombosis (DVT). Guides D-dimer and Doppler ultrasound ordering.
Centor/McIsaac Score (Pharyngitis)

Predicts Group A streptococcal (GAS) pharyngitis to guide throat swab and antibiotic prescribing decisions.
Caprini VTE Risk Assessment

Assesses VTE risk in surgical patients. Guides mechanical and pharmacological prophylaxis decisions.
CHA2DS2-VASc Score (AF Stroke Risk)

Estimates annual stroke risk in non-valvular AF. Guides anticoagulation decision (OAC vs no treatment) per ESC/NICE guidelines.
Maddrey Discriminant Function (Alcoholic Hepatitis)

Predicts 30-day mortality in alcoholic hepatitis. MDF >= 32 indicates severe disease where corticosteroids may be beneficial.
Lille Model (Steroid Response in Alcoholic Hepatitis)

Assesses response to corticosteroids at day 7 in severe alcoholic hepatitis (MDF >= 32). Lille score >= 0.45 = non-response; stop steroids.
Hyponatraemia Cause Algorithm

Works through the European (ESE/ESICM/ERA-EDTA 2014) diagnostic algorithm for hyponatraemia: serum osmolality, urine osmolality, urine sodium, diuretics or kidney disease, and extracellular fluid volume.
Hyperkalaemia Management Algorithm

Grades acute hyperkalaemia by serum potassium and ECG changes, with the treatment steps of the UK Kidney Association 2020 adult guideline (protect the heart, shift potassium into cells, remove potassium).
RECIST 1.1 — Response Evaluation in Solid Tumours

Standard radiological response criteria for solid tumours (Eisenhauer 2009). Compares the sum of diameters of up to 5 target lesions (2 per organ; longest diameter, or short axis for lymph nodes) with baseline (for response) and with the smallest sum on study (for progression), plus non-target and new lesions.
Nottingham Prognostic Index (NPI) for Breast Cancer

Prognostic index for operable primary breast cancer (Haybittle 1982): NPI = 0.2 × tumour size (cm) + node stage + grade. Groups with 10-year breast-cancer-specific survival from Blamey 2007.
PREDICT Breast Cancer 5- and 10-year Survival (Bands)

PREDICT Breast (Wishart 2010; version 3, Grootes 2024) estimates overall survival after surgery for early invasive breast cancer and the absolute benefit of adjuvant treatments. It is a survival model with many inputs and cannot be scored here — use the official tool at breast.predict.cam.
IMDC (Heng) Score for Metastatic RCC

International Metastatic RCC Database Consortium criteria for systemic-therapy-treated mRCC (Heng 2009). Sums 6 adverse factors. Predicts overall survival on first-line therapy and stratifies for combination therapy decisions.
G8 Geriatric Screening Tool (Oncology)

8-item screening tool for older adults with cancer (Bellera 2012; SIOG endorsed). Score ≤14/17 indicates need for full comprehensive geriatric assessment (CGA) before treatment decisions.
CRASH Score — Chemotherapy Risk Assessment Scale for High-Age

Predicts severe chemotherapy toxicity (grade 4 haematological or grade 3–4 non-haematological) in adults ≥ 70 (Extermann 2012) from diastolic BP, IADL, LDH, ECOG, MMSE, MNA and the regimen's toxicity (Chemotox). Combined score 0–12.
CARG — Cancer and Aging Research Group Chemotherapy Toxicity Score

11-item predictive tool for grade 3–5 chemotherapy toxicity in adults ≥ 65 with cancer (Hurria 2011, validated 2016): age, tumour type, dose, polychemotherapy, haemoglobin, creatinine clearance and five geriatric assessment items. Score 0–23.