For healthcare professionals
A–a Gradient & Alveolar Gas Equation
Alveolar oxygen (PAO₂) by the alveolar gas equation and the alveolar–arterial gradient.
Health tool library
Calculators, converters and scores built on cited methods — each with its methodology, references and limits.
What are you trying to calculate?
127 tools
For healthcare professionals
ABCD² Score for TIA
Early stroke risk after a transient ischaemic attack.
For healthcare professionals
Absolute Lymphocyte & Eosinophil Count
Absolute lymphocyte and eosinophil counts from the white cell count and differential.
For healthcare professionals
Absolute Neutrophil Count (ANC)
ANC from the white cell count and neutrophil (and band) percentages, with CTCAE grade.
For healthcare professionals
Adjusted Body Weight Calculator
Adjusted body weight (IBW + 0.4 × excess weight) for dosing and nutrition calculations.
Everyone & professionals
Albumin / Protein Unit Converter
Convert serum albumin or total protein between g/dL and g/L.
For healthcare professionals
Anion Gap Calculator
Serum anion gap, with albumin correction when albumin is entered.
For healthcare professionals
Apgar Score
Newborn condition at 1 and 5 minutes after birth.
For healthcare professionals
APRI (AST to Platelet Ratio Index)
AST-to-platelet ratio index for fibrosis and cirrhosis in chronic hepatitis C.
For healthcare professionals
Arterial Oxygen Content (CaO₂)
Oxygen carried by haemoglobin plus dissolved oxygen.
For healthcare professionals
AST/ALT Ratio (De Ritis Ratio)
The ratio of AST to ALT.
Everyone & professionals
Bilirubin Unit Converter
Convert bilirubin between mg/dL and µmol/L.
For healthcare professionals
Bishop Score
Cervical readiness for induction of labour.
Everyone & professionals
Blood Cell Count Unit Converter
Convert platelet or white cell counts between ×10⁹/L, ×10³/µL and /µL.
Blood Glucose Unit Converter
Convert blood glucose between mg/dL and mmol/L.
Blood Pressure Category Checker
See which ACC/AHA 2017 category a blood pressure reading falls in, with the ESC 2024 view alongside.
BMI Calculator
Calculate your body mass index and see the WHO adult category.
BMR Calculator
Basal metabolic rate by the Mifflin–St Jeor equation.
Body Fat Percentage Calculator
Estimate body fat from tape measurements (US Navy method).
Everyone & professionals
Body Surface Area Calculator
Body surface area by the Mosteller and DuBois formulas.
Body Temperature Converter
Convert temperature between Celsius, Fahrenheit and Kelvin.
For healthcare professionals
BSA-Adjusted (De-indexed) eGFR
Convert eGFR from mL/min/1.73 m² to mL/min for the patient's actual body size.
For healthcare professionals
Burn Fluid Resuscitation (Parkland / ABLS)
Estimated crystalloid volume for the first 24 hours after a major burn.
Caffeine Limit Calculator
The EFSA safe daily caffeine level for your age, weight and pregnancy status.
Everyone & professionals
Calcium Unit Converter
Convert calcium between mg/dL, mmol/L and mEq/L.
For healthcare professionals
Calculated LDL Cholesterol (Friedewald & NIH)
Estimate LDL cholesterol from a standard lipid panel using the Friedewald and NIH (Sampson) equations.
Calories Burned Calculator
Energy used by common activities, from Compendium MET values.
Carbohydrate Exchange Calculator
Convert grams of carbohydrate into 15-gram exchanges (carb choices).
For healthcare professionals
CHA₂DS₂-VASc / CHA₂DS₂-VA Score
Stroke risk score in atrial fibrillation, with the sex-neutral CHA₂DS₂-VA used by ESC 2024.
For healthcare professionals
Child–Pugh Score
Severity of cirrhosis from bilirubin, albumin, INR, ascites and encephalopathy.
Cholesterol Ratio Calculator
Total cholesterol to HDL ratio, and LDL to HDL ratio if you have LDL.
Cholesterol Unit Converter
Convert total, LDL, HDL or non-HDL cholesterol between mg/dL and mmol/L.
For healthcare professionals
CKD Stage & Risk Classification (KDIGO)
Combine eGFR and albuminuria into the KDIGO G/A classification and risk heat map.
For healthcare professionals
Corrected Calcium Calculator
Albumin-adjusted total calcium (simplified Payne formula).
For healthcare professionals
Corrected QT Interval (QTc) Calculator
Correct the QT interval for heart rate with Bazett, Fridericia, Framingham and Hodges.
For healthcare professionals
Corrected Reticulocyte Count & Reticulocyte Production Index
Correct the reticulocyte percentage for anaemia and maturation time.
For healthcare professionals
Corrected Sodium in Hyperglycemia
Sodium corrected for hyperglycaemia using the Katz (1.6) and Hillier (2.4) factors.
For healthcare professionals
CRB-65 Pneumonia Score (no blood test)
CURB-65 without urea, for use in the community.
For healthcare professionals
Creatinine Clearance (Cockcroft–Gault)
Estimated creatinine clearance for drug dosing, with actual, ideal and adjusted body weight.
Everyone & professionals
Creatinine Unit Converter
Convert serum creatinine between mg/dL and µmol/L.
For healthcare professionals
CURB-65 Pneumonia Severity Score
Severity of community-acquired pneumonia and 30-day mortality risk.
Daily Calorie Needs Calculator (TDEE)
Estimated daily energy needs from your BMR and physical activity level.
For healthcare professionals
Delta Gap & Delta Ratio Calculator
Delta gap and delta ratio to look for mixed acid–base disorders in high anion gap acidosis.
Everyone & professionals
eGFR Calculator (CKD-EPI 2021)
Estimate kidney filtration (eGFR) from serum creatinine, age and sex, without a race coefficient.
For healthcare professionals
eGFR from Creatinine and Cystatin C (CKD-EPI 2021)
Race-free CKD-EPI 2021 combined creatinine–cystatin C equation, plus cystatin C alone (2012).
For healthcare professionals
Electrolyte-Free Water Clearance
Electrolyte-free water clearance from urine output and urine/plasma electrolytes.
Fasting Blood Glucose Reference
See which ADA range a fasting plasma glucose result falls in, in mg/dL and mmol/L.
For healthcare professionals
FIB-4 Index for Liver Fibrosis
Non-invasive estimate of advanced liver fibrosis from age, AST, ALT and platelets.
Fiber Intake Calculator
Daily dietary fibre target from your calorie intake.
FINDRISC Diabetes Risk Score
The Finnish Diabetes Risk Score: estimated 10-year risk of developing type 2 diabetes.
Food Energy Converter (kcal ↔ kJ)
Convert food energy between kilocalories and kilojoules.
For healthcare professionals
Fractional Excretion of Sodium (FENa)
Fractional excretion of sodium from paired plasma and urine sodium and creatinine.
For healthcare professionals
Fractional Excretion of Urea (FEUrea)
Fractional excretion of urea, an alternative to FENa studied in AKI, including in patients who have received diuretics.
Free Sugar Limit Calculator
WHO limits for free (added) sugars in grams and teaspoons for your calorie intake.
For healthcare professionals
Free Water Deficit Calculator
Estimated free water deficit in hypernatraemia from sodium and total body water.
Everyone & professionals
Gestational Age from Due Date
Gestational age on any date from a known estimated due date (e.g. from an ultrasound).
For healthcare professionals
Glasgow Coma Scale (GCS)
Level of consciousness from eye, verbal and motor responses.
Glycemic Load Calculator
Glycemic load of a food portion from its glycemic index and carbohydrate content.
For healthcare professionals
HAS-BLED Bleeding Risk Score
One-year major bleeding risk in patients with atrial fibrillation on anticoagulation.
Everyone & professionals
HbA1c to Average Glucose Calculator
Convert an HbA1c result to estimated average glucose (eAG) and IFCC units.
HbA1c Unit Converter (% ↔ mmol/mol)
Convert HbA1c between NGSP percent and IFCC mmol/mol.
Healthy Weight Range Calculator
The weight range that matches a BMI of 18.5–24.9 for your height.
Heart Rate Reserve Calculator
The gap between your maximum and resting heart rate.
For healthcare professionals
HEART Score for Chest Pain
Risk of major adverse cardiac events within 6 weeks in emergency chest pain.
Height Converter (cm ↔ ft/in)
Convert height between centimetres, metres, inches and feet.
Everyone & professionals
Hemoglobin Unit Converter
Convert haemoglobin between g/dL, g/L and mmol/L.
For healthcare professionals
HOMA-IR Calculator
Homeostasis model assessment of insulin resistance from fasting glucose and insulin.
For healthcare professionals
Hunt and Hess Scale for Subarachnoid Haemorrhage
Clinical grading of aneurysmal subarachnoid haemorrhage.
Everyone & professionals
Ideal Body Weight Calculator
Ideal body weight by the Devine, Robinson, Miller and Hamwi equations.
For healthcare professionals
Infusion Duration Calculator
How long a volume takes to run at a given rate.
For healthcare professionals
Infusion Rate from Dose (mL/h)
Pump rate in mL/h for a prescribed dose and a known concentration (mcg/kg/min, mg/h, units/h …).
For healthcare professionals
IV Flow & Drip Rate Calculator
mL/hour and drops/minute from volume, time and the giving set's drop factor.
Everyone & professionals
Lean Body Weight Calculator
Estimated lean (fat-free) body weight by the Janmahasatian equation.
Everyone & professionals
Liver Enzyme Unit Converter (ALT/AST)
Convert ALT, AST, ALP or GGT between U/L and µkat/L.
Macronutrient Calculator
Carbohydrate, fat and protein ranges in grams for your daily calories.
Everyone & professionals
Magnesium Unit Converter
Convert magnesium between mg/dL, mmol/L and mEq/L.
Maximum Heart Rate Calculator
Age-predicted maximum heart rate (Tanaka and the traditional 220 − age).
For healthcare professionals
MDRD eGFR Calculator
The 4-variable IDMS-traceable MDRD equation, for comparison with older reports.
Everyone & professionals
Mean Arterial Pressure (MAP) Calculator
Estimate mean arterial pressure from systolic and diastolic blood pressure.
For healthcare professionals
MELD, MELD-Na and MELD 3.0
Model for End-Stage Liver Disease: original, sodium (2016 UNOS) and MELD 3.0 (2023 OPTN) versions.
For healthcare professionals
Mentzer Index
MCV divided by red cell count, to help separate thalassaemia trait from iron deficiency in microcytosis.
For healthcare professionals
Minute Ventilation Calculator
Minute ventilation from tidal volume and respiratory rate.
For healthcare professionals
Modified Rankin Scale (mRS)
Reference descriptions for the modified Rankin Scale of disability after stroke.
For healthcare professionals
Neutrophil-to-Lymphocyte & Platelet-to-Lymphocyte Ratios
Inflammation ratios from absolute neutrophil, lymphocyte and platelet counts.
For healthcare professionals
NEWS2 (National Early Warning Score 2)
Early warning score for acute illness severity from six physiological parameters.
Everyone & professionals
Non-HDL Cholesterol Calculator
Non-HDL cholesterol: total cholesterol minus HDL.
Ovulation & Fertile Window Calculator
Estimated ovulation day, fertile window and next period from your cycle.
For healthcare professionals
P/F Ratio (PaO₂/FiO₂)
PaO₂ to FiO₂ ratio, with Berlin ARDS oxygenation categories.
For healthcare professionals
Padua Prediction Score for VTE
Venous thromboembolism risk in hospitalised medical (non-surgical) patients.
For healthcare professionals
Paediatric Maintenance Fluids (Holliday–Segar)
Maintenance fluid volume by the Holliday–Segar (100/50/20 or 4-2-1) method.
For healthcare professionals
PERC Rule for Pulmonary Embolism
Pulmonary embolism rule-out criteria for patients with low clinical probability.
Everyone & professionals
Phosphate Unit Converter
Convert inorganic phosphate (as phosphorus) between mg/dL and mmol/L.
For healthcare professionals
Predicted Body Weight & Tidal Volume (ARDSNet)
Predicted body weight for ventilation and tidal volumes at 4–8 mL/kg.
Pregnancy Due Date Calculator
Estimated due date, current week of pregnancy and trimester from your last period.
Pregnancy Weight Gain Calculator
Recommended total weight gain for a single pregnancy from your pre-pregnancy BMI (IOM 2009).
Everyone & professionals
Pressure Unit Converter (mmHg ↔ kPa)
Convert blood pressure or blood gas values between mmHg, kPa and cmH₂O.
Protein Intake Calculator
Daily protein reference intake for healthy adults by body weight.
Everyone & professionals
Pulse Pressure Calculator
The difference between systolic and diastolic blood pressure.
For healthcare professionals
qSOFA (quick SOFA)
Bedside prompt for patients with suspected infection at risk of poor outcome (Sepsis-3).
For healthcare professionals
Revised Cardiac Risk Index (RCRI)
Cardiac risk before non-cardiac surgery (Lee index).
For healthcare professionals
Revised Geneva Score for PE
Pre-test probability of pulmonary embolism using only objective items.
Salt and Sodium Calculator
Convert sodium on food labels to salt and compare with the WHO limit.
Saturated Fat Limit Calculator
WHO upper limit for saturated fat in grams for your calorie intake.
For healthcare professionals
Serum Osmolality & Osmolar Gap
Calculated serum osmolality and, with a measured value, the osmolar gap.
For healthcare professionals
Shock Index & Modified Shock Index
Heart rate divided by systolic (SI) or mean arterial pressure (MSI).
Smoking Pack-Year Calculator
Measure lifetime cigarette exposure in pack-years.
For healthcare professionals
Sodium Deficit Calculator
Estimated sodium deficit in hyponatraemia, and the expected change in sodium per litre of a chosen fluid (Adrogué–Madias).
Everyone & professionals
Sodium, Potassium & Chloride Unit Converter
For monovalent electrolytes (sodium, potassium, chloride, bicarbonate) mmol/L and mEq/L are identical.
For healthcare professionals
SpO₂/FiO₂ Ratio (S/F)
Non-invasive oxygenation ratio from pulse oximetry, used in the 2023 global ARDS definition.
For healthcare professionals
STOP-Bang Questionnaire for Sleep Apnoea
Screening for obstructive sleep apnoea, often used before surgery.
Target Heart Rate Calculator
Heart rate zones for moderate and vigorous exercise (ACSM, Karvonen method).
For healthcare professionals
TIMI Risk Score for UA/NSTEMI
14-day risk of death, MI or urgent revascularisation in unstable angina or NSTEMI.
Triglyceride Unit Converter
Convert triglycerides between mg/dL and mmol/L.
Type 2 Diabetes Risk Test (ADA)
The American Diabetes Association's 7-question risk test for undiagnosed type 2 diabetes.
Everyone & professionals
Urea / BUN Converter
Convert between blood urea nitrogen (mg/dL) and urea (mmol/L or mg/dL).
Everyone & professionals
Uric Acid Unit Converter
Convert uric acid between mg/dL and µmol/L.
Everyone & professionals
Urine Albumin-to-Creatinine Ratio (UACR) Category
Place a urine albumin-to-creatinine ratio in KDIGO albuminuria category A1, A2 or A3.
For healthcare professionals
Urine Protein-to-Creatinine Ratio (UPCR)
Calculate UPCR from spot urine protein and creatinine and estimate daily protein excretion.
Volume Converter (mL ↔ oz)
Convert fluid volume between millilitres, litres, US fluid ounces and 250 mL cups.
Waist-to-Height Ratio Calculator
Check whether your waist size suggests extra fat around the middle.
Waist-to-Hip Ratio Calculator
Compare your waist and hip size using the WHO cut-offs.
Water Intake Calculator
Daily water needs from EFSA reference values, including pregnancy and breastfeeding.
For healthcare professionals
WBC Corrected for Nucleated Red Cells
Correct a white cell count that includes nucleated red blood cells.
Weight Converter (kg ↔ lb)
Convert body or food weight between kilograms, pounds, grams and ounces.
Weight Loss Timeline Calculator
A rough estimate of how long a steady calorie deficit takes to reach a goal weight.
For healthcare professionals
Wells Score for DVT
Pre-test probability of deep vein thrombosis (2003 modified version).
For healthcare professionals
Wells Score for Pulmonary Embolism
Pre-test probability of pulmonary embolism.
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