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.
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

Assesses risk of pressure ulcer development. Higher scores indicate higher 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 MMSE for mild cognitive impairment (MCI). Assesses 8 cognitive domains.
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

Detailed 17-condition comorbidity index predicting 10-year mortality. Age-adjusted version adds 1 point per decade after age 50.
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

Measures comorbidity burden using 31 weighted conditions. Predicts in-hospital mortality, length of stay, and resource utilisation.
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

Guides structured assessment of CPR appropriateness using clinical, ethical, and patient-centred domains. Supports DNACPR and ReSPECT documentation.
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. All values expressed as diazepam 5 mg equivalents. Note: equivalencies are approximate and require clinical judgement.
Carpal Tunnel Syndrome-6 (CTS-6) Diagnostic Tool

6-item clinical prediction rule for diagnosing carpal tunnel syndrome (CTS) without the need for nerve conduction studies (NCS). Items: nocturnal symptoms, hand diagram, wrist ratio index, Phalen's test, loss of 2-point discrimination, weakness/atrophy. Score ≥12 = high likelihood CTS.
Roth Score for Hypoxia Screening

Simple, validated bedside test for detecting hypoxaemia without pulse oximetry. Patient counts aloud from 1 as fast as possible on a single breath. Count-to-20 test: counts ≥20 AND breath-holding time ≥10 seconds effectively rules out SpO₂ <95%. Useful in resource-limited settings.
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

Systematically identifies the cause of hyponatraemia using plasma osmolality, urine osmolality, and urine sodium. Guides targeted treatment.
Hyperkalaemia Management Algorithm

Grades hyperkalaemia severity and guides sequential management from ECG stabilisation to potassium excretion per Renal Association/NICE guidelines.
RECIST 1.1 — Response Evaluation in Solid Tumours

Standard radiological response criteria for solid tumour clinical trials and routine oncology (Eisenhauer 2009). Assesses change in sum of longest diameters (SLD) of up to 5 target lesions vs baseline, and new lesions or unequivocal progression of non-target lesions.
Nottingham Prognostic Index (NPI) for Breast Cancer

Validated prognostic score for operable breast cancer (Haybittle 1982; revised). NPI = (0.2 × tumour size in cm) + nodal stage + tumour grade. Pick the band closest to your calculated value.
PREDICT Breast Cancer 5- and 10-year Survival (Bands)

PREDICT v3 (2024) is a Cambridge online tool estimating absolute benefit of adjuvant chemotherapy / endocrine / trastuzumab / bisphosphonates / chemo+olaparib (BRCA) in early breast cancer. This calc lets you record the calculated 10-year overall survival band and treatment recommendation summary. Always run the live tool at predict.nhs.uk for individualised numbers.
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

Stratifies risk of severe chemotherapy toxicity in adults ≥70 (Extermann 2012). Combines patient factors (haemoglobin, creatinine clearance, IADL, MMSE/MNA, ECOG, LDH) + chemotherapy regimen toxicity. Use the band closest to your calculated score.
CARG — Cancer and Aging Research Group Chemotherapy Toxicity Score

11-item predictive tool for grade 3+ chemotherapy toxicity in adults ≥65 with cancer (Hurria 2011, validated 2016). Age, tumour, regimen factors, lab values and geriatric assessment items. Score 0–19. Use the band closest to your calculated total.